National Library of Energy BETA

Sample records for reveals entire gamma-ray

  1. The Animated Gamma-ray Sky Revealed by the Fermi Gamma-ray Space Telescope

    ScienceCinema (OSTI)

    Isabelle Grenier

    2010-01-08

    The Fermi Gamma-ray Space Telescope has been observing the sky in gamma-rays since August 2008.  In addition to breakthrough capabilities in energy coverage (20 MeV-300 GeV) and angular resolution, the wide field of view of the Large Area Telescope enables observations of 20% of the sky at any instant, and of the whole sky every three hours. It has revealed a very animated sky with bright gamma-ray bursts flashing and vanishing in minutes, powerful active galactic nuclei flaring over hours and days, many pulsars twinkling in the Milky Way, and X-ray binaries shimmering along their orbit. Most of these variable sources had not been seen by the Fermi predecessor, EGRET, and the wealth of new data already brings important clues to the origin of the high-energy emission and particles powered by the compact objects. The telescope also brings crisp images of the bright gamma-ray emission produced by cosmic-ray interactions in the interstellar medium, thus allowing to measure the cosmic nuclei and electron spectra across the Galaxy, to weigh interstellar clouds, in particular in the dark-gas phase. The telescope sensitivity at high energy will soon provide useful constraints on dark-matter annihilations in a variety of environments. I will review the current results and future prospects of the Fermi mission.

  2. NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Atwood, W. B.; Baldini, L.; Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M.; Bruel, P.; Cohen-Tanugi, J.; Granot, J.; Longo, F.; Razzaque, S.; Zimmer, S. E-mail: nicola.omodei@stanford.edu

    2013-09-01

    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

  3. GLAST Observatory Renamed for Fermi, Reveals Entire Gamma-Ray Sky |

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergy A plug-inPPLforLDRD Report11, SolarMat 4" | DepartmentJuneDecember 2015

  4. Gamma Ray Bursts

    E-Print Network [OSTI]

    Stahl, Bennett

    2014-01-01

    Olson. “Observations of gamma-ray bursts of cosmic origin. ”E. Lingenfelter. “Gamma-ray bursts. ” Annual Review of652-654. Waxman, Eli. “Gamma-ray-burst afterglow: supporting

  5. DNA microarray analyses reveal a post-irradiation differential time-dependent gene expression profile in yeast cells exposed to X-rays and {gamma}-rays

    SciTech Connect (OSTI)

    Kimura, Shinzo [Laboratory of Environmental Biology, Department of Preventive Medicine, Hokkaido University School of Medicine, Sapporo 060-8638 (Japan); Ishidou, Emi [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Kurita, Sakiko [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Suzuki, Yoshiteru [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Shibato, Junko [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Rakwal, Randeep [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)]. E-mail: rakwal-68@aist.go.jp; Iwahashi, Hitoshi [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

    2006-07-21

    Ionizing radiation (IR) is the most enigmatic of genotoxic stress inducers in our environment that has been around from the eons of time. IR is generally considered harmful, and has been the subject of numerous studies, mostly looking at the DNA damaging effects in cells and the repair mechanisms therein. Moreover, few studies have focused on large-scale identification of cellular responses to IR, and to this end, we describe here an initial study on the transcriptional responses of the unicellular genome model, yeast (Saccharomyces cerevisiae strain S288C), by cDNA microarray. The effect of two different IR, X-rays, and gamma ({gamma})-rays, was investigated by irradiating the yeast cells cultured in YPD medium with 50 Gy doses of X- and {gamma}-rays, followed by resuspension of the cells in YPD for time-course experiments. The samples were collected for microarray analysis at 20, 40, and 80 min after irradiation. Microarray analysis revealed a time-course transcriptional profile of changed gene expressions. Up-regulated genes belonged to the functional categories mainly related to cell cycle and DNA processing, cell rescue defense and virulence, protein and cell fate, and metabolism (X- and {gamma}-rays). Similarly, for X- and {gamma}-rays, the down-regulated genes belonged to mostly transcription and protein synthesis, cell cycle and DNA processing, control of cellular organization, cell fate, and C-compound and carbohydrate metabolism categories, respectively. This study provides for the first time a snapshot of the genome-wide mRNA expression profiles in X- and {gamma}-ray post-irradiated yeast cells and comparatively interprets/discusses the changed gene functional categories as effects of these two radiations vis-a-vis their energy levels.

  6. Gamma ray generator

    DOE Patents [OSTI]

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

    An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

  7. Gamma Ray Bursts Sudden, intense flashes of gamma rays

    E-Print Network [OSTI]

    Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

    Gamma Ray Bursts #12;The Case Sudden, intense flashes of gamma rays come from nowhere and disappear with out a trace. Incredibly powerful: A single gamma ray burst is hundreds of times brighter a supernova #12;Who Vela (1960's) Looking for arms testing, found gamma ray bursts Compton Gamma Ray Observatory

  8. Gamma Ray Pulsars: Observations

    E-Print Network [OSTI]

    David J. Thompson

    2001-01-03

    High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. Unless a new pulsed component appears at higher energies, progress in gamma-ray pulsar studies will be greatest in the 1-20 GeV range. Ground-based telescopes whose energy ranges extend downward toward 10 GeV should make important measurements of the spectral cutoffs. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2005, will provide a major advance in sensitivity, energy range, and sky coverage.

  9. Gamma-Ray Bursts

    E-Print Network [OSTI]

    P. Meszaros

    2006-05-30

    Gamma-ray bursts are the most luminous explosions in the Universe, and their origin and mechanism are the focus of intense research and debate. More than three decades after their discovery, and after pioneering breakthroughs from space and ground experiments, their study is entering a new phase with the recently launched Swift satellite. The interplay between these observations and theoretical models of the prompt gamma ray burst and its afterglow is reviewed.

  10. Gamma ray camera

    DOE Patents [OSTI]

    Perez-Mendez, Victor (Berkeley, CA)

    1997-01-01

    A gamma ray camera for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array.

  11. Gamma ray camera

    DOE Patents [OSTI]

    Perez-Mendez, V.

    1997-01-21

    A gamma ray camera is disclosed for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array. 6 figs.

  12. Gamma ray bursts in their historic context

    E-Print Network [OSTI]

    Trimble, V

    2004-01-01

    Gamma Ray Bursts In Their Historic Context Virginia TrimbleMD 20742 USA Abstract. Gamma ray bursts remained essentiallyalso applies to the gamma ray bursts. First, an observation

  13. Gamma Ray Bursts

    E-Print Network [OSTI]

    Peter Mészáros

    2012-04-12

    Gamma-ray bursts have been detected at photon energies up to tens of GeV. We review some recent developments in the X-ray to GeV photon phenomenology in the light of Swift and Fermi observations, and some of the theoretical models developed to explain them, with a view towards implications for C.T.A.

  14. Fermi Observations of Gamma-ray Bursts

    SciTech Connect (OSTI)

    Ohno, Masanori [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2010-10-15

    The gamma-ray emission mechanism of Gamma-ray bursts (GRBs) are still unknown. Fermi Gamma-ray Space Telescope successfully detected high-energy (> 100 MeV) emission from 17 GRBs since its launch. Fermi revealed the distinct temporal behaviors and extra spectral component from high-energy emission. These new observational results are driving many theoretical implications, such as leptonic, hadronic and afterglow origin. The highest energy photon detected by Fermi gives a constraint on the bulk Lorentz factor of the ultra-relativistic jets of GRBs. The impact of the Fermi GRB observations extends not only to the GRB-related issues but also to the outside GRB physics, such as quantum gravity and model of the extra galactic background light.

  15. SciTech Connect: "gamma ray bursts"

    Office of Scientific and Technical Information (OSTI)

    gamma ray bursts" Find + Advanced Search Term Search Semantic Search Advanced Search All Fields: "gamma ray bursts" Semantic Semantic Term Title: Full Text: Bibliographic Data:...

  16. Gamma-Ray Burst Lines

    E-Print Network [OSTI]

    Michael S. Briggs

    1999-10-20

    The evidence for spectral features in gamma-ray bursts is summarized. As a guide for evaluating the evidence, the properties of gamma-ray detectors and the methods of analyzing gamma-ray spectra are reviewed. In the 1980's, observations indicated that absorption features below 100 keV were present in a large fraction of bright gamma-ray bursts. There were also reports of emission features around 400 keV. During the 1990's the situation has become much less clear. A small fraction of bursts observed with BATSE have statistically significant low-energy features, but the reality of the features is suspect because in several cases the data of the BATSE detectors appear to be inconsistent. Furthermore, most of the possible features appear in emission rather than the expected absorption. Analysis of data from other instruments has either not been finalized or has not detected lines.

  17. Gamma Ray Bursts and CETI

    E-Print Network [OSTI]

    Frank D. Smith Jr

    1993-02-10

    Gamma ray burst sources are isotropically distributed. They could be located at distances $\\sim 1000$ AU. (Katz \\cite{JK92}) GRB signals have many narrow peaks that are unresolved at the millisecond time resolution of existing observations. \\cite{JK87} CETI could use stars as gravitational lenses for interstellar gamma ray laser beam communication. Much better time resolution of GRB signals could rule out (or confirm?) the speculative hypothesis that GRB = CETI.

  18. Gamma ray bursts ROBERT S MACKAY

    E-Print Network [OSTI]

    Rourke, Colin

    Gamma ray bursts ROBERT S MACKAY COLIN ROURKE We propose that a gamma ray burst is a kinematic Gamma ray bursts are intense flashes of electromagnetic radiation of cosmic origin lasting from ten accepted mechanism. We propose that a gamma ray burst is simply a kinematic effect, namely the effect

  19. Gamma-RayGamma-Ray Bursts: from SwiftBursts: from Swift

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Gamma-RayGamma-Ray Bursts: from SwiftBursts: from Swift to GLASTto GLAST Bing ZhangBing ZhangGehrels, et al), et al) #12;Gamma-ray bursts: the mostGamma-ray bursts: the most violent explosions fireball central photosphere internal external shocks engine (shocks) (reverse) (forward) gamma-ray UV

  20. And the remaining 22 photons: The development of gamma ray and gamma ray burst astronomy

    E-Print Network [OSTI]

    Trimble, V

    2005-01-01

    goblins and cosmic gamma ray bursts. Astrophysics and Spacelinear alignments of gamma-ray burst sources. Journal of theE.E. (eds. ), 1992. Gamma Ray Bursts. Cambridge, Cambridge

  1. Gamma-ray Imaging Methods

    SciTech Connect (OSTI)

    Vetter, K; Mihailescu, L; Nelson, K; Valentine, J; Wright, D

    2006-10-05

    In this document we discuss specific implementations for gamma-ray imaging instruments including the principle of operation and describe systems which have been built and demonstrated as well as systems currently under development. There are several fundamentally different technologies each with specific operational requirements and performance trade offs. We provide an overview of the different gamma-ray imaging techniques and briefly discuss challenges and limitations associated with each modality (in the appendix we give detailed descriptions of specific implementations for many of these technologies). In Section 3 we summarize the performance and operational aspects in tabular form as an aid for comparing technologies and mapping technologies to potential applications.

  2. Classification of Fermi Gamma-RAY Bursts

    E-Print Network [OSTI]

    Horvath, I; Hakkila, J; Bagoly, Z; Preece, R D

    2015-01-01

    The Fermi GBM Catalog has been recently published. Previous classification analyses of the BATSE, RHESSI, BeppoSAX, and Swift databases found three types of gamma-ray bursts. Now we analyzed the GBM catalog to classify the GRBs. PCA and Multiclustering analysis revealed three groups. Validation of these groups, in terms of the observed variables, shows that one of the groups coincides with the short GRBs. The other two groups split the long class into a bright and dim part, as defined by the peak flux. Additional analysis is needed to determine whether this splitting is only a mathematical byproduct of the analysis or has some real physical meaning.

  3. TeV GAMMA-RAY SURVEY OF THE NORTHERN HEMISPHERE SKY USING THE MILAGRO OBSERVATORY R. Atkins,1,2

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    to search the entire northern hemisphere for such objects. The search for short bursts of TeV gamma rays hasTeV GAMMA-RAY SURVEY OF THE NORTHERN HEMISPHERE SKY USING THE MILAGRO OBSERVATORY R. Atkins,1,2 W) are presented. The data have been searched for steady point sources of TeV gamma rays between declinations of 1

  4. Portable compton gamma-ray detection system

    DOE Patents [OSTI]

    Rowland, Mark S. (Alamo, CA); Oldaker, Mark E. (Pleasanton, CA)

    2008-03-04

    A Compton scattered gamma-ray detector system. The system comprises a gamma-ray spectrometer and an annular array of individual scintillators. The scintillators are positioned so that they are arrayed around the gamma-ray spectrometer. The annular array of individual scintillators includes a first scintillator. A radiation shield is positioned around the first scintillator. A multi-channel analyzer is operatively connected to the gamma-ray spectrometer and the annular array of individual scintillators.

  5. Light Curves of Swift Gamma Ray Bursts

    E-Print Network [OSTI]

    Paolo Cea

    2006-09-22

    Recent observations from the Swift gamma-ray burst mission indicate that a fraction of gamma ray bursts are characterized by a canonical behaviour of the X-ray afterglows. We present an effective theory which allows us to account for X-ray light curves of both (short - long) gamma ray bursts and X-ray rich flashes. We propose that gamma ray bursts originate from massive magnetic powered pulsars.

  6. The Universe Viewed in Gamma-Rays 1 Properties of Gamma-ray Bursts Localized by

    E-Print Network [OSTI]

    Enomoto, Ryoji

    The Universe Viewed in Gamma-Rays 1 Properties of Gamma-ray Bursts Localized by the HETE-2 and localize Gamma-ray bursts (GRBs) in wide field of view. HETE-2 have been localized about 20 GRBs per year hours after the burst. 1. The High Energy Transient Explorer 2 Gamma-ray burst (GRB) is the most

  7. The Diverse Environments of Gamma-Ray Bursts

    E-Print Network [OSTI]

    Perley, Daniel Alan

    2011-01-01

    of a Very Bright Gamma- Ray Burst in a Galactic Halo 3.1Galaxies of Dark Gamma-Ray Bursts: Observational Constraints1.3 Gamma-Ray Burst Classi?cation . . . . . . 1.4 Gamma-Ray

  8. Gamma Ray Bursts from Minijets

    E-Print Network [OSTI]

    Nir J. Shaviv; Arnon Dar

    1994-07-14

    Striking similarities exist between high energy gamma ray emission from active galactic nuclei (AGN) and gamma ray bursts (GRBs). They suggest that GRBs are generated by inverse Compton scattering from highly relativistic electrons in transient jets. Such jets may be produced along the axis of an accretion disk formed around stellar black holes (BH) or neutron stars (NS) in BH-NS and NS-NS mergers and in accretion induced collapse of magnetized white dwarfs (WD) or neutron stars in close binary systems. Such events may produce the cosmological GRBs. Transient jets formed by single old magnetized neutron stars in an extended Galactic halo may produce a local population of GRBs. Here we show that jet production of GRBs by inverse Compton scattering can explain quite simply the striking correlations that exist between various temporal features of GRBs, their duration histogram, the power spectrum of their complex multipeak light curves, their power-law high energy spectra and other features of GRBs. Some additional predictions are made including the expected polarization of gamma-rays in the bursts.

  9. Gamma Ray Burst Central Engines

    E-Print Network [OSTI]

    Todd A. Thompson

    2008-07-04

    I review aspects of the theory of long-duration gamma-ray burst (GRB) central engines. I focus on the requirements of any model; these include the angular momentum of the progenitor, the power, Lorentz factor, asymmetry, and duration of the flow, and both the association and the non-association with bright supernovae. I compare and contrast the collapsar and millisecond proto-magnetar models in light of these requirements. The ability of the latter model to produce a flow with Lorentz factor ~100 while simultaneously maintaining a kinetic luminosity of ~10^50 ergs/s for a timescale of ~10-100 s is emphasized.

  10. Black Stars and Gamma Ray Bursts

    E-Print Network [OSTI]

    Tanmay Vachaspati

    2007-06-08

    Stars that are collapsing toward forming a black hole but are frozen near the Schwarzschild horizon are termed ``black stars''. Collisions of black stars, in contrast to black hole collisions, may be sources of gamma ray bursts, whose basic parameters are estimated quite simply and are found to be consistent with observed gamma ray bursts. Black star gamma ray bursts should be preceded by gravitational wave emission similar to that from the coalescence of black holes.

  11. Gamma-ray irradiated polymer optical waveguides

    SciTech Connect (OSTI)

    Lai, C.-C.; Wei, T.-Y.; Chang, C.-Y.; Wang, W.-S.; Wei, Y.-Y.

    2008-01-14

    Optical waveguides fabricated by gamma-ray irradiation on polymer through a gold mask are presented. The gamma-ray induced index change is found almost linearly dependent on the dose of the irradiation. And the measured propagation losses are low enough for practical application. Due to the high penetrability of gamma ray, uniform refractive index change in depth can be easily achieved. Moreover, due to large-area printing, the uniformity of waveguide made by gamma-ray irradiation is much better than that by e-beam direct writing.

  12. REVISITING THE LIGHT CURVES OF GAMMA-RAY BURSTS IN THE RELATIVISTIC TURBULENCE MODEL

    SciTech Connect (OSTI)

    Lin, Da-Bin; Gu, Wei-Min; Hou, Shu-Jin; Liu, Tong; Sun, Mou-Yuan; Lu, Ju-Fu, E-mail: dabinlin@xmu.edu.cn, E-mail: lujf@xmu.edu.cn [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)

    2013-10-10

    Rapid temporal variability has been widely observed in the light curves of gamma-ray bursts (GRBs). One possible mechanism for such variability is related to the relativistic eddies in the jet. In this paper, we include the contribution of the inter-eddy medium together with the eddies to the gamma-ray emission. We show that the gamma-ray emission can either lead or lag behind the observed synchrotron emission, where the latter originates in the inter-eddy medium and provides most of the seed photons for producing gamma-ray emission through inverse Compton scattering. As a consequence, we argue that the lead/lag found in non-stationary short-lived light curves may not reveal the intrinsic lead/lag of different emission components. In addition, our results may explain the lead of gamma-ray emission with respect to optical emission observed in GRB 080319B.

  13. Gravitational Waves versus X and Gamma Ray Emission in a Short Gamma-Ray Burst

    E-Print Network [OSTI]

    F. G. Oliveira; Jorge A. Rueda; Remo Ruffini

    2014-03-28

    The recent progress in the understanding the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst, GRB 090227B, allows to give an estimate of the gravitational waves versus the X and Gamma-ray emission in a short gamma-ray burst.

  14. CONSTRAINTS ON VERY HIGH ENERGY GAMMA-RAY EMISSION FROM GAMMA-RAY BURSTS R. Atkins,1,2

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    CONSTRAINTS ON VERY HIGH ENERGY GAMMA-RAY EMISSION FROM GAMMA-RAY BURSTS R. Atkins,1,2 W. Benbow,3 emission from gamma-ray bursts (GRBs) during the prompt emission phase. Detection of >100 GeV counterparts on potential GRB models. Subject headinggs: gamma rays: bursts -- gamma rays: observations 1. INTRODUCTION

  15. GAMMA-400 gamma-ray observatory

    E-Print Network [OSTI]

    Topchiev, N P; Bonvicini, V; Adriani, O; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Bakaldin, A V; Bergstrom, L; Berti, E; Bigongiari, G; Bobkov, S G; Boezio, M; Bogomolov, E A; Bonechi, L; Bongi, M; Bottai, S; Castellini, G; Cattaneo, P W; Cumani, P; Dalkarov, O D; Dedenko, G L; De Donato, C; Dogiel, V A; Finetti, N; Gascon, D; Gorbunov, M S; Gusakov, Yu V; Hnatyk, B I; Kadilin, V V; Kaplin, V A; Kaplun, A A; Kheymits, M D; Korepanov, V E; Larsson, J; Leonov, A A; Loginov, V A; Longo, F; Maestro, P; Marrocchesi, P S; Martinez, M; Menshenin, A L; Mikhailov, V V; Mocchiutti, E; Moiseev, A A; Mori, N; Moskalenko, I V; Naumov, P Yu; Papini, P; Paredes, J M; Pearce, M; Picozza, P; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Serdin, O V; Sparvoli, R; Spillantini, P; Stozhkov, Yu I; Suchkov, S I; Taraskin, A A; Tavani, M; Tiberio, A; Tyurin, E M; Ulanov, M V; Vacchi, A; Vannuccini, E; Vasilyev, G I; Ward, J E; Yurkin, Yu T; Zampa, N; Zirakashvili, V N; Zverev, V G

    2015-01-01

    The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons + positrons. Precision investigations of gamma-ray emission from Galactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well as diffuse gamma-ray emission, along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will study gamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The energy range of GAMMA-400 is expected to be from ~20 MeV up to TeV energies for gamma rays, up to 20 TeV for electrons + positrons, and up to 10E15 eV for cosmic-ray nuclei. For high-energy gamma rays with energy from 10 to 100 GeV, the GAMMA-400 angular resolution improves from 0.1{\\deg} to ~0.01{\\deg} and energy resolution from 3% to ~1%; the proton rejection factor is ~5x10E5. GAMMA-400 will be installed onboard the Russian space observatory.

  16. CLOAKED GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Eichler, David, E-mail: eichler.david@gmail.com [Physics Department, Ben-Gurion University, Be'er-Sheva 84105 (Israel)

    2014-06-01

    It is suggested that many gamma-ray bursts (GRBs) are cloaked by an ultrarelativistic baryonic shell that has high optical depth when the photons are manufactured. Such a shell would not fully block photons reflected or emitted from its inner surface, because the radial velocity of the photons can be less than that of the shell. This avoids the standard problem associated with GRBs that the thermal component should be produced where the flow is still obscured by high optical depth. The radiation that escapes high optical depth obeys the Amati relation. Observational implications may include (1) anomalously high ratios of afterglow to prompt emission, such as may have been the case in the recently discovered PTF 11agg, and (2) ultrahigh-energy neutrino pulses that are non-coincident with detectable GRB. It is suggested that GRB 090510, a short, very hard GRB with very little afterglow, was an exposed GRB, in contrast to those cloaked by baryonic shells.

  17. A history of gamma ray bursts and other astronomical conundrums

    E-Print Network [OSTI]

    Trimble, V; Trimble, V

    2006-01-01

    V. Trimble, in “Gamma Ray Bursts: 30 Years of Discovery,”V. Trimble, in “Gamma Ray Bursts,” Ed. C. Ho et al. ,A History of Gamma Ray Bursts and Other Astronomical

  18. Observations of Gamma-Ray Bursts at Extreme Energies

    E-Print Network [OSTI]

    Aune, Taylor

    2012-01-01

    of Gamma-Ray Bursts . . . . . . . . . . . . . Redshift-Ancient Unvierse with Gamma-Ray Bursts, pages 330–333. AIP,A. Olson. Observations of Gamma-Ray Bursts of Cosmic Origin.

  19. THE BATSE 5B GAMMA-RAY BURST SPECTRAL CATALOG

    SciTech Connect (OSTI)

    Goldstein, Adam; Preece, Robert D.; Briggs, Michael S.; Burgess, J. Michael [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Mallozzi, Robert S.; Fishman, Gerald J.; Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Paciesas, William S. [Universities Space Research Association, 320 Sparkman Drive, Huntsville, AL 35805 (United States)

    2013-10-01

    We present systematic spectral analyses of gamma-ray bursts (GRBs) detected with the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory during its entire nine years of operation. This catalog contains two types of spectra extracted from 2145 GRBs, and fitted with five different spectral models resulting in a compendium of over 19,000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was devised to be as thorough and objective as possible. We describe in detail our procedures and criteria for the analyses, and present the bulk results in the form of parameter distributions. This catalog should be considered an official product from the BATSE Science Team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC)

  20. Recombining plasma in the gamma-ray-emitting mixed-morphology supernova remnant 3C 391

    SciTech Connect (OSTI)

    Ergin, T.; Sezer, A.; Saha, L.; Majumdar, P.; Chatterjee, A.; Bayirli, A.; Ercan, E. N.

    2014-07-20

    A group of middle-aged mixed-morphology (MM) supernova remnants (SNRs) interacting with molecular clouds (MCs) has been discovered to be strong GeV gamma-ray emitters by the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope (Fermi-LAT). The recent observations of the Suzaku X-ray satellite have revealed that some of these interacting gamma-ray-emitting SNRs, such as IC443, W49B, W44, and G359.1-0.5, have overionized plasmas. 3C 391 (G31.9+0.0) is another Galactic MM SNR interacting with MCs. It was observed in GeV gamma rays by Fermi-LAT as well as in the 0.3-10.0 keV X-ray band by Suzaku. In this work, 3C 391 was detected in GeV gamma rays with a significance of ?18? and we showed that the GeV emission is point-like in nature. The GeV gamma-ray spectrum was shown to be best explained by the decay of neutral pions assuming that the protons follow a broken power-law distribution. We revealed radiative recombination structures of silicon and sulfur from 3C 391 using Suzaku data. In this paper, we discuss the possible origin of this type of radiative plasma and hadronic gamma rays.

  1. CONTRIBUTION OF GAMMA-RAY-LOUD RADIO GALAXIES' CORE EMISSIONS...

    Office of Scientific and Technical Information (OSTI)

    The Fermi gamma-ray satellite has recently detected gamma-ray emissions from radio galaxy cores. From these samples, we first examine the correlation between the luminosities...

  2. Gamma-Ray Bursts and Particle Astrophysics

    E-Print Network [OSTI]

    B. Gendre

    2008-07-24

    Gamma-ray bursts are violent events occurring randomly in the sky. In this review, I will present the fireball model, proposed to explain the phenomenon of gamma-ray bursts. This model has important consequences for the production and observation at Earth of gravitational waves, high energy neutrinos, cosmic rays and high energy photons, and the second part of this review will be focused on these aspects. A last section will briefly discuss the topic of the use of gamma-ray bursts as standard candles and possible cosmological studies.

  3. Energetics of Gamma Ray Bursts

    E-Print Network [OSTI]

    Raul Jimenez; David Band; Tsvi Piran

    2001-03-16

    We determine the distribution of total energy emitted by gamma-ray bursts for bursts with fluences and distance information. Our core sample consists of eight bursts with BATSE spectra and spectroscopic redshifts. We extend this sample by adding four bursts with BATSE spectra and host galaxy R magnitudes. From these R magnitudes we calculate a redshift probability distribution; this method requires a model of the host galaxy population. From a sample of ten bursts with both spectroscopic redshifts and host galaxy R magnitudes (some do not have BATSE spectra) we find that the burst rate is proportional to the galaxy luminosity at the epoch of the burst. Assuming that the total energy emitted has a log-normal distribution, we find that the average emitted energy (assumed to be radiated isotropically) is $ = 1.3^{+1.2}_{-1.0} \\times 10^{53}$ ergs (for H$_0$ = 65 km s$^{-1}$ Mpc$^{-1}$, $\\Omega_m=0.3$ and $\\Omega_\\Lambda=0.7$); the distribution has a logarithmic width of $\\sigma_\\gamma=1.7^{+0.7}_{-0.3}$. The corresponding distribution of X-ray afterglow energy (for seven bursts) has $ = 4.0^{+1.6}_{-1.8} \\times 10^{51}$ergs and $\\sigma_X = 1.3^{+0.4}_{-0.3}$. For completeness, we also provide spectral fits for all bursts with BATSE spectra for which there were afterglow searches.

  4. Gamma-ray Burst Cosmology

    E-Print Network [OSTI]

    Wang, F Y; Liang, E W

    2015-01-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to $8.8\\times10^{54}$ erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it...

  5. Thermal neutron capture gamma-rays

    SciTech Connect (OSTI)

    Tuli, J.K.

    1983-01-01

    The energy and intensity of gamma rays as seen in thermal neutron capture are presented. Only those (n,..cap alpha..), E = thermal, reactions for which the residual nucleus mass number is greater than or equal to 45 are included. These correspond to evaluations published in Nuclear Data Sheets. The publication source data are contained in the Evaluated Nuclear Structure Data File (ENSDF). The data presented here do not involve any additional evaluation. Appendix I lists all the residual nuclides for which the data are included here. Appendix II gives a cumulated index to A-chain evaluations including the year of publication. The capture gamma ray data are given in two tables - the Table 1 is the list of all gamma rays seen in (n,..gamma..) reaction given in the order of increasing energy; the Table II lists the gamma rays according to the nuclide.

  6. Gravitational waves and gamma-ray bursts

    E-Print Network [OSTI]

    Alessandra Corsi; for the LIGO Scientific Collaboration; for the Virgo Collaboration

    2012-05-11

    Gamma-Ray Bursts are likely associated with a catastrophic energy release in stellar mass objects. Electromagnetic observations provide important, but indirect information on the progenitor. On the other hand, gravitational waves emitted from the central source, carry direct information on its nature. In this context, I give an overview of the multi-messenger study of gamma-ray bursts that can be carried out by using electromagnetic and gravitational wave observations. I also underline the importance of joint electromagnetic and gravitational wave searches, in the absence of a gamma-ray trigger. Finally, I discuss how multi-messenger observations may probe alternative gamma-ray burst progenitor models, such as the magnetar scenario.

  7. Can gamma-ray bursts constrain quintessence?

    E-Print Network [OSTI]

    T. Di Girolamo; R. Catena; M. Vietri; G. Di Sciascio

    2005-04-27

    Using the narrow clustering of the geometrically corrected gamma-ray energies released by gamma-ray bursts, we investigate the possibility of using these sources as standard candles to probe cosmological parameters such as the matter density Omega_m and the cosmological constant energy density Omega_Lambda. By simulating different samples of gamma-ray bursts, we find that Omega_m can be determined with accuracy ~7% with data from 300 sources. We also show that, if Omega = 1 is due to a quintessence field, some of the models proposed in the literature may be discriminated from a Universe with cosmological constant, by a similar-sized sample of gamma-ray bursts.

  8. Studying Gamma Ray Bursts from a

    E-Print Network [OSTI]

    ?umer, Slobodan

    Studying Gamma Ray Bursts from a new perspective! {... Unraveling some mysteries and adding new Radio Op0cal X-ray Short ( energy -ray photons... ... accompained by a considerable long las0ng emission

  9. Gamma Ray Bursts from Ordinary Cosmic Strings

    E-Print Network [OSTI]

    R. H. Brandenberger; A. T. Sornborger; M. Trodden

    1993-02-12

    We give an upper estimate for the number of gamma ray bursts from ordinary (non-superconducting) cosmic strings expected to be observed at terrestrial detectors. Assuming that cusp annihilation is the mechanism responsible for the bursts we consider strings arising at a GUT phase transition and compare our estimate with the recent BATSE results. Further we give a lower limit for the effective area of future detectors designed to detect the cosmic string induced flux of gamma ray bursts.

  10. The HAWC Gamma-Ray Observatory: Sensitivity to Steady and Transient Sources of Gamma Rays

    E-Print Network [OSTI]

    Abeysekara, A U; Alvarez, C; Álvarez, J D; Arceo, R; Arteaga-Velázquez, J C; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; Belmont, E; BenZvi, S Y; Berley, D; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Carramińana, A; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Díaz-Vélez, J C; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fernandez, A; Fiorino, D W; Fraija, N; Galindo, A; Garfias, F; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Hampel-Arias, Z; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-GarcIa, R; Marinelli, A; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Rivičre, C; Rosa-González, D; Salazar, H; Salesa, F; Sanchez, F E; Sandoval, A; Santos, E; Schneider, M; Silich, S; Sinnis, G; Smith, A J; Sparks, K; Springer, R W; Taboada, I; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Villaseńor, L; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2013-01-01

    The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is designed to record air showers produced by cosmic rays and gamma rays between 100 GeV and 100 TeV. Because of its large field of view and high livetime, HAWC is well-suited to measure gamma rays from extended sources, diffuse emission, and transient sources. We describe the sensitivity of HAWC to emission from the extended Cygnus region as well as other types of galactic diffuse emission; searches for flares from gamma-ray bursts and active galactic nuclei; and the first measurement of the Crab Nebula with HAWC-30.

  11. Results from the Milagro Gamma-Ray Observatory

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    V energies, and a search for transient emission above 100 GeV from gamma-ray bursts. 1 Introduction remnants and gamma-ray bursts (GRB). Gamma rays are also produced when high-energy cosmic rays interactResults from the Milagro Gamma-Ray Observatory E. Blaufuss for the Milagro Collaboration a,1 , a

  12. Long gamma-ray bursts trace the star formation history

    SciTech Connect (OSTI)

    Dado, Shlomo; Dar, Arnon [Physics Department, Technion, Haifa 32000 (Israel)

    2014-04-10

    We show that if the broad-line supernova explosions of Type Ic (SNeIc) produce the bulk of the observed long duration gamma-ray bursts (LGRBs), including high- and low-luminosity LGRBs and X-ray flashes, and if the LGRBs have the geometry assumed in the cannonball model of LGRBs, then their rate, measured by Swift, and their redshift distribution are consistent with the star formation rate (SFR) over the entire range of redshifts where the SFR has been measured with sufficient accuracy.

  13. The Universe Viewed in Gamma-Rays 1 Toward Ultra Short Gamma Ray Burst Ground Based De-

    E-Print Network [OSTI]

    Enomoto, Ryoji

    The Universe Viewed in Gamma-Rays 1 Toward Ultra Short Gamma Ray Burst Ground Based De- tection- liminary data taking started in November 2002. 1. Introduction Gamma-ray bursts observed with space Tcherenkovlightfromoneshower Few 100MeV gamma-rays Fig. 1. In an imaging telescope, -ray bursts should appear as a Cherenkov

  14. Gamma ray lines from a universal extra dimension

    SciTech Connect (OSTI)

    Bertone, G.; Jackson, C. B.; Shaughnessy, G.; Tait, T. M.P.; Vallinotto, A.

    2012-03-01

    Indirect Dark Matter searches are based on the observation of secondary particles produced by the annihilation or decay of Dark Matter. Among them, gamma-rays are perhaps the most promising messengers, as they do not suffer deflection or absorption on Galactic scales, so their observation would directly reveal the position and the energy spectrum of the emitting source. Here, we study the detailed gamma-ray energy spectrum of Kaluza--Klein Dark Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on the two body annihilation of Dark Matter particles into a photon and another particle, which produces monochromatic photons, resulting in a line in the energy spectrum of gamma rays. Previous calculations in the context of the five dimensional UED model have computed the line signal from annihilations into \\gamma \\gamma, but we extend these results to include \\gamma Z and \\gamma H final states. We find that these spectral lines are subdominant compared to the predicted \\gamma \\gamma signal, but they would be important as follow-up signals in the event of the observation of the \\gamma \\gamma line, in order to distinguish the 5d UED model from other theoretical scenarios.

  15. TEMPORAL CORRELATIONS BETWEEN OPTICAL AND GAMMA-RAY ACTIVITY IN BLAZARS

    SciTech Connect (OSTI)

    Cohen, Daniel P.; Filippenko, Alexei V.; Zheng, WeiKang; Li, Weidong; Romani, Roger W.; Cenko, S. Bradley

    2014-12-20

    We have been using the 0.76 m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory to optically monitor a sample of 157 blazars that are bright in gamma-rays being detected with high significance (?10?) in one year by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. We attempt to observe each source on a three-day cadence with KAIT, subject to weather and seasonal visibility. The gamma-ray coverage is essentially continuous. KAIT observations extend over much of the five-year Fermi mission for several objects, and most have >100 optical measurements spanning the last three years. These blazars (flat-spectrum radio quasars and BL Lac objects) exhibit a wide range of flaring behavior. Using the discrete correlation function (DCF), here we search for temporal relationships between optical and gamma-ray light curves in the 40 brightest sources in hopes of placing constraints on blazar acceleration and emission zones. We find strong optical-gamma-ray correlation in many of these sources at time delays of ?1 to ?10 days, ranging between –40 and +30 days. A stacked average DCF of the 40 sources verifies this correlation trend, with a peak above 99% significance indicating a characteristic time delay consistent with 0 days. These findings strongly support the widely accepted leptonic models of blazar emission. However, we also find examples of apparently uncorrelated flares (optical flares with no gamma-ray counterpart and gamma-ray flares with no optical counterpart) that challenge simple, one-zone models of blazar emission. Moreover, we find that flat-spectrum radio quasars tend to have gamma-rays leading the optical, while intermediate- and high-synchrotron peak blazars with the most significant peaks have smaller lags/leads. It is clear that long-term monitoring at high cadence is necessary to reveal the underlying physical correlation.

  16. Observations of the Isotropic Diffuse Gamma-ray Background with the EGRET Telescope

    E-Print Network [OSTI]

    T. D. Willis

    2002-01-30

    An Isotropic Diffuse Gamma-Ray Background (IDGRB) in the spectral range 30-10,000 MeV was first reported in the early 1970's using measurements made by the SAS-2 instrument. Data recorded by the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory (CGRO) over the last 4 years are analysed in order to extract the best measurement yet made of the IDGRB. Extensive analysis of the EGRET instrumental background is presented in order to demonstrate that an uncontaminated data set can be extracted from the EGRET data. A model of the high latitude galactic diffuse foreground emission is presented and the existence of an IDGRB is confirmed. Spatial and spectral analysis of this background is presented. In addition, point source analysis at high galactic latitudes is performed to reveal the existence of a population of extragalactic sources. The characteristics of this population are examined and models of its flux distribution are reported. The question of whether the IDGRB is composed of unresolved point sources is addressed using fluctuation analysis. Finally, possible future directions for gamma ray astronomy are examined through simulations of a future gamma ray telescope: the Gamma-ray Large Area Space Telescope (GLAST). The GLAST baseline design is described and its scientific performance is evaluated. The ability of this telescope to detect 1,000-10,000 new extragalactic sources is demonstrated and the likely impact on the study of the IDGRB is considered.

  17. Gamma Ray Bursts in the HAWC Era

    E-Print Network [OSTI]

    Mészáros, Peter; Murase, Kohta; Fox, Derek; Gao, He; Senno, Nicholas

    2015-01-01

    Gamma-Ray Bursts are the most energetic explosions in the Universe, and are among the most promising for detecting multiple non-electromagnetic signals, including cosmic rays, high energy neutrinos and gravitational waves. The multi-GeV to TeV gamma-ray range of GRB could have significant contributions from hadronic interactions, mixed with more conventional leptonic contributions. This energy range is important for probing the source physics, including overall energetics, the shock parameters and the Lorentz factor. We discuss some of the latest observational and theoretical developments in the field.

  18. Status of the Milagro $\\gamma$ Ray Observatory

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    2001-01-01

    The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

  19. Status of the Milagro Gamma Ray Observatory

    E-Print Network [OSTI]

    R. Atkins; W. Benbow; D. Berley; M. -L. Chen; D. G. Coyne; R. S. Delay; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; D. Evans; A. Falcone; L. Fleysher; R. Fleysher; G. Gisler; J. A. Goodman; T. J. Haines; C. M. Hoffman; S. Hugenberger; L. A. Kelley; I. Leonor; J. Macri; M. McConnell; J. F. McCullough; J. E. McEnery; R. S. Miller; A. I. Mincer; M. F. Morales; P. Nemethy; J. M. Ryan; M. Schneider; B. Shen; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; T. N. Thompson; O. T. Tumer; K. Wang; M. O. Wascko; S. Westerhoff; D. A. Williams; T. Yang; G. B. Yodh

    1999-06-24

    The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

  20. Gamma Ray Bursts in the HAWC Era

    E-Print Network [OSTI]

    Peter Mészáros; Katsuaki Asano; Kohta Murase; Derek Fox; He Gao; Nicholas Senno

    2015-06-08

    Gamma-Ray Bursts are the most energetic explosions in the Universe, and are among the most promising for detecting multiple non-electromagnetic signals, including cosmic rays, high energy neutrinos and gravitational waves. The multi-GeV to TeV gamma-ray range of GRB could have significant contributions from hadronic interactions, mixed with more conventional leptonic contributions. This energy range is important for probing the source physics, including overall energetics, the shock parameters and the Lorentz factor. We discuss some of the latest observational and theoretical developments in the field.

  1. Gamma-Ray Burst observations with Fermi

    E-Print Network [OSTI]

    Bissaldi, Elisabetta; Omodei, Nicola; Vianello, Giacomo; von Kienlin, Andreas

    2015-01-01

    After seven years of science operation, the Fermi mission has brought great advances in the study of Gamma-ray Bursts (GRBs). Over 1600 GRBs have been detected by the Gamma-ray Burst Monitor, and more than 100 of these are also detected by the Large Area Telescope above 30 MeV. We will give an overview of these observations, presenting the common properties in the GRB temporal and spectral behavior at high energies. We will also highlight the unique characteristics of some individual bursts. The main physical implications of these results will be discussed, along with open questions regarding GRB modeling in their prompt and temporally-extended emission phases.

  2. A supersymmetric model of gamma ray bursts

    E-Print Network [OSTI]

    L. Clavelli; G. Karatheodoris

    2005-08-08

    We propose a model for gamma ray bursts in which a star subject to a high level of fermion degeneracy undergoes a phase transition to a supersymmetric state. The burst is initiated by the transition of fermion pairs to sfermion pairs which, uninhibited by the Pauli exclusion principle, can drop to the ground state of minimum momentum through photon emission. The jet structure is attributed to the Bose statistics of sfermions whereby subsequent sfermion pairs are preferentially emitted into the same state (sfermion amplification by stimulated emission). Bremsstrahlung gamma rays tend to preserve the directional information of the sfermion momenta and are themselves enhanced by stimulated emission.

  3. Gamma-Ray Bursts: Jets and Energetics

    E-Print Network [OSTI]

    D. A. Frail

    2003-11-12

    The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.

  4. Nucleosynthesis in gamma-ray bursts outflows

    E-Print Network [OSTI]

    M. Lemoine

    2002-06-19

    It is shown that fusion of neutrons and protons to He-4 nuclei occurs in gamma-ray burst outflows in a process similar to big-bang nucleosynthesis in the early Universe. Only the surviving free neutrons can then decouple kinematically from the charged fluid so that the multi-GeV neutrino signal predicted from inelastic nuclear n-p collisions is significantly reduced. It is also argued that a sizeable fraction of ultra-high energy cosmic rays accelerated in gamma-ray bursts should be He-4 nuclei.

  5. Internal energy dissipation of gamma-ray bursts observed with Swift: Precursors, prompt gamma-rays, extended emission, and late X-ray flares

    SciTech Connect (OSTI)

    Hu, You-Dong; Liang, En-Wei; Xi, Shao-Qiang; Peng, Fang-Kun; Lu, Rui-Jing; Lü, Lian-Zhong [Department of Physics and GXU-NAOC Center for Astrophysics and Space Sciences, Guangxi University, Nanning 530004 (China); Zhang, Bing, E-mail: lew@gxu.edu.cn, E-mail: Zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2014-07-10

    We jointly analyze the gamma-ray burst (GRB) data observed with Burst Alert Telescope (BAT) and X-ray Telescope on board the Swift mission to present a global view on the internal energy dissipation processes in GRBs, including precursors, prompt gamma-ray emission, extended soft gamma-ray emission, and late X-ray flares. The Bayesian block method is utilized to analyze the BAT light curves to identify various emission episodes. Our results suggest that these emission components likely share the same physical origin, which is the repeated activation of the GRB central engine. What we observe in the gamma-ray band may be a small part of more extended underlying activities. The precursor emission, which is detected in about 10% of Swift GRBs, is preferably detected in those GRBs that have a massive star core-collapse origin. The soft extended emission tail, on the other hand, is preferably detected in those GRBs that have a compact star merger origin. Bright X-ray emission is detected during the BAT quiescent phases prior to subsequent gamma-ray peaks, implying that X-ray emission may be detectable prior the BAT trigger time. Future GRB alert instruments with soft X-ray capability are essential for revealing the early stages of GRB central engine activities, and shedding light on jet composition and the jet launching mechanism in GRBs.

  6. Observation of the Crab Nebula in Soft Gamma Rays with the Nuclear Compton Telescope

    E-Print Network [OSTI]

    Bandstra, Mark ShenYu

    2010-01-01

    Gamma-ray bursts . . . . . . . . . . . . . . . . . . . 1.268] G. J. Fishman. The gamma-ray burst capabilities of BATSEOlson. Observations of Gamma- Ray Bursts of Cosmic Origin.

  7. Gamma-Ray Pulsars: Models and Predictions

    E-Print Network [OSTI]

    Alice K. Harding

    2000-12-12

    Pulsed emission from gamma-ray pulsars originates inside the magnetosphere, from radiation by charged particles accelerated near the magnetic poles or in the outer gaps. In polar cap models, the high energy spectrum is cut off by magnetic pair production above an energy that is dependent on the local magnetic field strength. While most young pulsars with surface fields in the range B = 10^{12} - 10^{13} G are expected to have high energy cutoffs around several GeV, the gamma-ray spectra of old pulsars having lower surface fields may extend to 50 GeV. Although the gamma-ray emission of older pulsars is weaker, detecting pulsed emission at high energies from nearby sources would be an important confirmation of polar cap models. Outer gap models predict more gradual high-energy turnovers at around 10 GeV, but also predict an inverse Compton component extending to TeV energies. Detection of pulsed TeV emission, which would not survive attenuation at the polar caps, is thus an important test of outer gap models. Next-generation gamma-ray telescopes sensitive to GeV-TeV emission will provide critical tests of pulsar acceleration and emission mechanisms.

  8. High redshift Gamma-Ray Bursts

    E-Print Network [OSTI]

    Salvaterra, R

    2015-01-01

    Ten years of operations of the Swift satellite have allow us to collect a small sample of long Gamma-Ray Bursts (GRBs) at redshift larger than six. I will review here the present status of this research field and discuss the possible use of GRBs as a fundamental new tool to explore the early Universe, complementary to quasar and galaxy surveys.

  9. Delayed Nickel Decay in Gamma Ray Bursts

    E-Print Network [OSTI]

    G. C. McLaughlin; R. A. M. J. Wijers

    2002-05-19

    Recently observed emission lines in the X-ray afterglow of gamma ray bursts suggest that iron group elements are either produced in the gamma ray burst, or are present nearby. If this material is the product of a thermonuclear burn, then such material would be expected to be rich in Nickel-56. If the nickel remains partially ionized, this prevents the electron capture reaction normally associated with the decay of Nickel-56, dramatically increasing the decay timescale. Here we examine the consequences of rapid ejection of a fraction of a solar mass of iron group material from the center of a collapsar/hypernova. The exact rate of decay then depends on the details of the ionization and therefore the ejection process. Future observations of iron, nickel and cobalt lines can be used to diagnose the origin of these elements and to better understand the astrophysical site of gamma ray bursts. In this model, the X-ray lines of these iron-group elements could be detected in suspected hypernovae that did not produce an observable gamma ray burst due to beaming.

  10. Gamma-ray bursts: a Centauro's cry?

    E-Print Network [OSTI]

    Z. K. Silagadze

    2003-06-30

    A new candidate for the gamma-ray bursts central engine is proposed: if in some energetic cosmic event a macroscopic amount of bubbles of the disoriented chiral condensate can be formed, then their subsequent decays will produce a relativistic fireball without the baryon loading problem. The neutron star to strange star transition is considered as a candidate example of such cosmic event.

  11. The Gamma Ray Detection Capabilities of the Alpha Magnetic Spectrometer

    E-Print Network [OSTI]

    R. Battiston; M. Biasini; E. Fiandrini; J. Petrakis; M. H. Salamon

    1999-09-30

    The modeled performance of the Alpha Magnetic Spectrometer (AMS) as a high energy (0.3 to 100 GeV) gamma-ray detector is described, and its gamma ray astrophysics objectives are discussed.

  12. Gamma-Ray Bursts, Ultra High Energy Cosmic Rays, and Cosmic Gamma-Ray Background

    E-Print Network [OSTI]

    Tomonori Totani

    1999-04-13

    We argue that gamma-ray bursts (GRBs) may be the origin of the cosmic gamma-ray background radiation observed in GeV range. It has theoretically been discussed that protons may carry a much larger amount of energy than electrons in GRBs, and this large energy can be radiated in TeV range by synchrotron radiation of ultra-high-energy protons (\\sim 10^{20} eV). The possible detection of GRBs above 10 TeV suggested by the Tibet and HEGRA groups also supports this idea. If this is the case, most of TeV gamma-rays from GRBs are absorbed in intergalactic fields and eventually form GeV gamma-ray background, whose flux is in good agreement with the recent observation.

  13. Gamma-Ray Bursts Nuclear Test Ban Treaty, 1963

    E-Print Network [OSTI]

    Harrison, Thomas

    Lecture 18 Gamma-Ray Bursts #12;Nuclear Test Ban Treaty, 1963 First Vela satellite pair launched and their predecessors, Vela 4, discovered the first gamma-ray bursts. The discovery was announced by Klebesadel, Strong, and Olson (ApJ, 182, 85) in 1973. #12;First Gamma-Ray Burst The Vela 5 satellites functioned from July, 1969

  14. SGARFACE: a novel detector for microsecond gamma ray bursts

    E-Print Network [OSTI]

    SGARFACE: a novel detector for microsecond gamma ray bursts S. LeBohec *,1 , F. Krennrich, G surveys and monitors for clas- sical gamma ray bursts. The sensitivity of these telescopes is limited 2005 Abstract The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) is operated at the Whipple

  15. Gamma-Ray Library and Uncertainty Analysis: Passively Emitted Gamma Rays Used in Safeguards Technology

    SciTech Connect (OSTI)

    Parker, W

    2009-09-18

    Non-destructive gamma-ray analysis is a fundamental part of nuclear safeguards, including nuclear energy safeguards technology. Developing safeguards capabilities for nuclear energy will certainly benefit from the advanced use of gamma-ray spectroscopy as well as the ability to model various reactor scenarios. There is currently a wide variety of nuclear data that could be used in computer modeling and gamma-ray spectroscopy analysis. The data can be discrepant (with varying uncertainties), and it may difficult for a modeler or software developer to determine the best nuclear data set for a particular situation. To use gamma-ray spectroscopy to determine the relative isotopic composition of nuclear materials, the gamma-ray energies and the branching ratios or intensities of the gamma-rays emitted from the nuclides in the material must be well known. A variety of computer simulation codes will be used during the development of the nuclear energy safeguards, and, to compare the results of various codes, it will be essential to have all the {gamma}-ray libraries agree. Assessing our nuclear data needs allows us to create a prioritized list of desired measurements, and provides uncertainties for energies and especially for branching intensities. Of interest are actinides, fission products, and activation products, and most particularly mixtures of all of these radioactive isotopes, including mixtures of actinides and other products. Recent work includes the development of new detectors with increased energy resolution, and studies of gamma-rays and their lines used in simulation codes. Because new detectors are being developed, there is an increased need for well known nuclear data for radioactive isotopes of some elements. Safeguards technology should take advantage of all types of gamma-ray detectors, including new super cooled detectors, germanium detectors and cadmium zinc telluride detectors. Mixed isotopes, particularly mixed actinides found in nuclear reactor streams can be especially challenging to identify. The super cooled detectors have a marked improvement in energy resolution, allowing the possibility of deconvolution of mixtures of gamma rays that was unavailable with high purity germanium detectors. Isotopic analysis codes require libraries of gamma rays. In certain situations, isotope identification can be made in the field, sometimes with a short turnaround time, depending on the choice of detector and software analysis package. Sodium iodide and high purity germanium detectors have been successfully used in field scenarios. The newer super cooled detectors offer dramatically increased resolution, but they have lower efficiency and so can require longer collection times. The different peak shapes require software development for the specific detector type and field application. Libraries can be tailored to specific scenarios; by eliminating isotopes that are certainly not present, the analysis time may be shortened and the accuracy may be increased. The intent of this project was to create one accurate library of gamma rays emitted from isotopes of interest to be used as a reliable reference in safeguards work. All simulation and spectroscopy analysis codes can draw upon this best library to improve accuracy and cross-code consistency. Modeling codes may include MCNP and COG. Gamma-ray spectroscopy analysis codes may include MGA, MGAU, U235 and FRAM. The intent is to give developers and users the tools to use in nuclear energy safeguards work. In this project, the library created was limited to a selection of actinide isotopes of immediate interest to reactor technology. These isotopes included {sup 234-238}U, {sup 237}Np, {sup 238-242}Pu, {sup 241,243}Am and {sup 244}Cm. These isotopes were examined, and the best of gamma-ray data, including line energies and relative strengths were selected.

  16. Real time gamma-ray signature identifier

    DOE Patents [OSTI]

    Rowland, Mark (Alamo, CA); Gosnell, Tom B. (Moraga, CA); Ham, Cheryl (Livermore, CA); Perkins, Dwight (Livermore, CA); Wong, James (Dublin, CA)

    2012-05-15

    A real time gamma-ray signature/source identification method and system using principal components analysis (PCA) for transforming and substantially reducing one or more comprehensive spectral libraries of nuclear materials types and configurations into a corresponding concise representation/signature(s) representing and indexing each individual predetermined spectrum in principal component (PC) space, wherein an unknown gamma-ray signature may be compared against the representative signature to find a match or at least characterize the unknown signature from among all the entries in the library with a single regression or simple projection into the PC space, so as to substantially reduce processing time and computing resources and enable real-time characterization and/or identification.

  17. Neutron-driven gamma-ray laser

    DOE Patents [OSTI]

    Bowman, Charles D. (Los Alamos, NM)

    1990-01-01

    A lasing cylinder emits laser radiation at a gamma-ray wavelength of 0.87 .ANG. when subjected to an intense neutron flux of about 400 eV neutrons. A 250 .ANG. thick layer of Be is provided between two layers of 100 .ANG. thick layer of .sup.57 Co and these layers are supported on a foil substrate. The coated foil is coiled to form the lasing cylinder. Under the neutron flux .sup.57 Co becomes .sup.58 Co by neutron absorption. The .sup.58 Co then decays to .sup.57 Fe by 1.6 MeV proton emission. .sup.57 Fe then transitions by mesne decay to a population inversion for lasing action at 14.4 keV. Recoil from the proton emission separates the .sup.57 Fe from the .sup.57 Co and into the Be, where Mossbauer emission occurs at a gamma-ray wavelength.

  18. Fissile interrogation using gamma rays from oxygen

    DOE Patents [OSTI]

    Smith, Donald; Micklich, Bradley J.; Fessler, Andreas

    2004-04-20

    The subject apparatus provides a means to identify the presence of fissionable material or other nuclear material contained within an item to be tested. The system employs a portable accelerator to accelerate and direct protons to a fluorine-compound target. The interaction of the protons with the fluorine-compound target produces gamma rays which are directed at the item to be tested. If the item to be tested contains either a fissionable material or other nuclear material the interaction of the gamma rays with the material contained within the test item with result in the production of neutrons. A system of neutron detectors is positioned to intercept any neutrons generated by the test item. The results from the neutron detectors are analyzed to determine the presence of a fissionable material or other nuclear material.

  19. Lorentz violation from gamma-ray bursts

    E-Print Network [OSTI]

    Shu Zhang; Bo-Qiang Ma

    2014-06-18

    The constancy of light speed is a basic assumption in Einstein's special relativity, and consequently the Lorentz invariance is a fundamental symmetry of space-time in modern physics. However, it is speculated that the speed of light becomes energy-dependent due to the Lorentz invariance violation~(LV) in various new physics theories. We analyse the data of the energetic photons from the gamma-ray bursts (GRBs) by the Fermi Gamma-Ray Space Telescope, and find more events to support the energy dependence in the light speed with both linear and quadratic form corrections. We provide two scenarios to understand all the new-released Pass~8 data of bright GRBs by the Fermi-LAT Collaboration, with predictions from such scenarios being testable by future detected GRBs.

  20. Are gamma-ray bursts cosmological?

    E-Print Network [OSTI]

    Horvath, I

    2015-01-01

    Gamma-ray burst sources are distributed with a high level of isotropy, which is compatible with either a cosmological origin or an extended Galactic halo origin. The brightness distribution is another indicator used to characterize the spatial distribution in distance. In this paper the author discusses detailed fits of the BATSE gamma-ray burst peak-flux distributions with Friedmann models taking into account possible density evolution and standard candle luminosity functions. A chi-square analysis is used to estimate the goodness of the fits and the author derives the significance level of limits on the density evolution and luminosity function parameters. Cosmological models provide a good fit over a range of parameter space which is physically reasonable

  1. Gamma-Ray Bursts: Progress, Problems & Prospects

    E-Print Network [OSTI]

    Bing Zhang; Peter Meszaros

    2003-11-13

    The cosmological gamma-ray burst (GRB) phenomenon is reviewed. The broad observational facts and empirical phenomenological relations of the GRB prompt emission and afterglow are outlined. A well-tested, successful fireball shock model is introduced in a pedagogical manner. Several important uncertainties in the current understanding of the phenomenon are reviewed, and prospects of how future experiments and extensive observational and theoretical efforts may address these problems are discussed.

  2. Cosmological Time Dilation in Gamma Ray Bursts?

    E-Print Network [OSTI]

    David Band

    1994-07-01

    Norris et al. (1994) report that the temporal structure of faint gamma ray bursts is longer than that of bright bursts, as expected for time dilation in the cosmological models of burst origin. I show that the observed trends can easily be produced by a burst luminosity function and thus may not result from cosmological effects. A cosmological signature may be present, but the tests Norris et al. present are not powerful enough to detect these signatures.

  3. Gamma-Ray Line Observations with RHESSI

    E-Print Network [OSTI]

    David M. Smith

    2004-04-30

    The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has been observing gamma-ray lines from the Sun and the Galaxy since its launch in February 2002. Here I summarize the status of RHESSI observations of solar lines (nuclear de-excitation, neutron capture, and positron annihilation), the lines of $^{26}$Al and $^{60}$Fe from the inner Galaxy, and the search for positron annihilation in novae.

  4. Energetic Runaway Electrons, Sprites and Gamma Rays

    E-Print Network [OSTI]

    Lehtinen, Nikolai G.

    of Terrestrial Gamma Ray Flashes (BATSE Data) Rate(counts/0.1ms)Rate(counts/0.1ms)Rate(counts/0.1ms) Time (ms. Inan, U. S., S. C. Reising, G. J. Fishman and J. M. Horack, On the association of terrestrial gamma. V. Gurevich, T. Tunnel and G. M. Milikh, Kinetic theory of runaway breakdown, Phys. Rev., 49, 2257

  5. Gamma-Ray Bursts as a Cosmic Window for Galaxy Evolution

    E-Print Network [OSTI]

    I. F. Mirabel; D. B. Sanders; E. Le Floc'h

    2000-04-03

    Present knowledge indicates that gamma-ray bursts are linked with massive stars. They will become invaluable probes of the early universe and galaxy formation. In the future, it will be possible to use gamma-ray bursts for two purposes: 1) to probe the history of massive star formation in the Universe by the rate of occurence of gamma-ray bursts, and 2) for the study of galaxy evolution at all lookback times by determining the nature of the galaxy hosts. Because gamma-rays are not attenuated by intervening dust and gas, the selection of the cosmic sites of massive star formation by this method is less affected by the biases associated with optical-uv surveys (e.g. UV-dropout techniques). Infrared and sub-millimeter follow up studies of the hosts of gamma-ray bursts may: 1) reveal a putative population of reddened ($R-K \\geq 4$) galaxies at high redshifts, and 2) detect very massive stars (population III) formed at $z \\geq$ 5.

  6. GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES

    SciTech Connect (OSTI)

    Storm, Emma M.; Jeltema, Tesla E.; Profumo, Stefano [Department of Physics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2012-08-20

    Star formation in galaxies is observed to be associated with gamma-ray emission, presumably from non-thermal processes connected to the acceleration of cosmic-ray nuclei and electrons. The detection of gamma rays from starburst galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation rate and gamma-ray luminosity. Since star formation is known to scale with total infrared (8-1000 {mu}m) and radio (1.4 GHz) luminosity, the observed infrared and radio emission from a star-forming galaxy can be used to quantitatively infer the galaxy's gamma-ray luminosity. Similarly, star-forming galaxies within galaxy clusters allow us to derive lower limits on the gamma-ray emission from clusters, which have not yet been conclusively detected in gamma rays. In this study, we apply the functional relationships between gamma-ray luminosity and radio and IR luminosities of galaxies derived by the Fermi Collaboration to a sample of the best candidate galaxy clusters for detection in gamma rays in order to place lower limits on the gamma-ray emission associated with star formation in galaxy clusters. We find that several clusters have predicted gamma-ray emission from star formation that are within an order of magnitude of the upper limits derived in Ackermann et al. based on non-detection by Fermi-LAT. Given the current gamma-ray limits, star formation likely plays a significant role in the gamma-ray emission in some clusters, especially those with cool cores. We predict that both Fermi-LAT over the course of its lifetime and the future Cerenkov Telescope Array will be able to detect gamma-ray emission from star-forming galaxies in clusters.

  7. Gamma-ray Output Spectra from 239 Pu Fission

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ullmann, John

    2015-05-25

    Gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. A dependence of the gamma-ray spectrum on the gamma-raymore »multplicity was also observed. Global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.« less

  8. Gamma-ray burst data from DMSP satellites

    SciTech Connect (OSTI)

    Terrell, J.; Klebesadel, R.W.; Lee, P. ); Griffee, J.W. )

    1991-01-01

    A number of gamma-ray bursts have been detected by means of gamma-ray detectors aboard three Air Force Defense Meteorological Satellite Program (DMSP) satellites, in polar orbits at 800 km altitude. The gamma-ray data have a 2-second resolving time, and are usually telemetered in 5 energy bins in the range 50--1000 keV. Although it is not possible to detect gamma-ray bursts when the DMSP satellites are passing through the radiation belt or the South Atlantic Anomaly, or when the source is obscured by the Earth, a number of gamma-ray bursts have been detected by two or even three of the satellites. The DMSP data may be of considerable, assistance in evaluating time histories, locations, and spectra of gamma-ray bursts.

  9. Gamma-ray burst data from DMSP satellites

    SciTech Connect (OSTI)

    Terrell, J.; Klebesadel, R.W.; Lee, P.; Griffee, J.W.

    1991-12-31

    A number of gamma-ray bursts have been detected by means of gamma-ray detectors aboard three Air Force Defense Meteorological Satellite Program (DMSP) satellites, in polar orbits at 800 km altitude. The gamma-ray data have a 2-second resolving time, and are usually telemetered in 5 energy bins in the range 50--1000 keV. Although it is not possible to detect gamma-ray bursts when the DMSP satellites are passing through the radiation belt or the South Atlantic Anomaly, or when the source is obscured by the Earth, a number of gamma-ray bursts have been detected by two or even three of the satellites. The DMSP data may be of considerable, assistance in evaluating time histories, locations, and spectra of gamma-ray bursts.

  10. Can Naked Singularities Yield Gamma Ray Bursts?

    E-Print Network [OSTI]

    H. M. Antia

    1998-07-09

    Gamma-ray bursts are believed to be the most luminous objects in the Universe. There has been some suggestion that these arise from quantum processes around naked singularities. The main problem with this suggestion is that all known examples of naked singularities are massless and hence there is effectively no source of energy. It is argued that a globally naked singularity coupled with quantum processes operating within a distance of the order of Planck length of the singularity will probably yield energy burst of the order of M_pc^2\\approx2\\times 10^{16} ergs, where M_p is the Planck mass.

  11. Gamma Ray Burst Neutrinos Probing Quantum Gravity

    E-Print Network [OSTI]

    M. C. Gonzalez-Garcia; F. Halzen

    2006-11-28

    Very high energy, short wavelength, neutrinos may interact with the space-time foam predicted by theories of quantum gravity. They would propagate like light through a crystal lattice and be delayed, with the delay depending on the energy. This will appear to the observer as a violation of Lorenz invariance. Back of the envelope calculations imply that observations of neutrinos produced by gamma ray bursts may reach Planck-scale sensitivity. We revisit the problem considering two essential complications: the imprecise timing of the neutrinos associated with their poorly understood production mechanism in the source and the indirect nature of their energy measurement made by high energy neutrino telescopes.

  12. THE ORTHOGONAL GAMMA-RAY BURST MODEL

    SciTech Connect (OSTI)

    Contopoulos, Ioannis; Pugliese, Daniela; Nathanail, Antonios

    2014-01-01

    We explore the analogy between a rotating magnetized black hole and an axisymmetric pulsar and derive the black hole's electromagnetic spindown after its formation in the core collapse of a supermassive star. The spindown shows two characteristic phases: an early Blandford-Znajek phase that lasts a few hundred seconds and a late pulsar-like afterglow phase that lasts much longer. During the first phase, the spindown luminosity decreases almost exponentially, whereas during the afterglow phase it decreases as t {sup –a} with 1 ? a ? 1.5. We associate our findings with long duration gamma-ray bursts and compare them with observations.

  13. Gamma-Ray Bursts observed by INTEGRAL

    E-Print Network [OSTI]

    S. Mereghetti

    2003-12-12

    During the first six months of operations, six Gamma Ray Bursts (GRBs) have been detected in the field of view of the INTEGRAL instruments and localized by the INTEGRAL Burst Alert System (IBAS): a software for the automatic search of GRBs and the rapid distribution of their coordinates. I describe the current performances of IBAS and review the main results obtained so far. The coordinates of the latest burst localized by IBAS, GRB 031203, have been distributed within 20 s from the burst onset and with an uncertainty radius of only 2.7 arcmin.

  14. AGNs and microquasars as high energy gamma-ray sources

    E-Print Network [OSTI]

    Josep M. Paredes

    2004-12-02

    The extragalactic analogs of the microquasars, the quasars, are strong gamma-ray emitters at GeV energies. It is expected that microquasars are also gamma-ray sources, because of the analogy with quasars and because theoretical models predict the high-energy emission. There are two microquasars that appear as the possible counterparts for two unidentified high-energy gamma-ray sources.

  15. Nuclear Criticality as a Contributor to Gamma Ray Burst Events

    E-Print Network [OSTI]

    Robert Bruce Hayes

    2013-01-15

    Most gamma ray bursts are able to be explained using supernovae related phenomenon. Some measured results still lack compelling explanations and a contributory cause from nuclear criticality is proposed. This is shown to have general properties consistent with various known gamma ray burst properties. The galactic origin of fast rise exponential decay gamma ray bursts is considered a strong candidate for these types of events.

  16. Gamma-ray Bursts as Probes of Galaxy Evolution

    E-Print Network [OSTI]

    ?umer, Slobodan

    Gamma-ray Bursts as Probes of Galaxy Evolution Daniele Malesani, Dark Cosmology Centre and the X of the "Universe") #12;What is a gamma-ray burst? Brief (ms - min) and intense (~10-7 erg cm­2 s­1 ) burst of soft to ongoing star formation "Naked-eye" GRB 080319B GRBs explode within star-forming galaxies Gamma-ray bursts

  17. Gamma Ray Bursts, Neutron Star Quakes, and the Casimir Effect

    E-Print Network [OSTI]

    C. Carlson; T. Goldman; J. Perez-Mercader

    1994-11-25

    We propose that the dynamic Casimir effect is a mechanism that converts the energy of neutron starquakes into $\\gamma$--rays. This mechanism efficiently produces photons from electromagnetic Casimir energy released by the rapid motion of a dielectric medium into a vacuum. Estimates based on the cutoff energy of the gamma ray bursts and the volume involved in a starquake indicate that the total gamma ray energy emission is consonant with observational requirements.

  18. Inelastic cross sections from gamma-ray measurements

    SciTech Connect (OSTI)

    Nelson, Ronald Owen [Los Alamos National Laboratory

    2010-12-06

    Measurements of gamma rays following neutron induced reactions have been studied with the Germanium Array for Neutron-induced Excitations (GEANIE) at the Los Alamos Neutron Science Center (LANSCE) for many years. Gamma-ray excitation functions and coincidence studies provide insight into nuclear reaction mechanisms as well as expanding our knowledge of energy levels and gamma-rays. Samples studied with Ge detectors at LANSCE range from Be to Pu. Fe, Cr and Ti have been considered for use as reference cross sections. An overview of the measurements and efforts to create a reliable neutron-induced gamma-ray reference cross section will be presented.

  19. Radio flares from gamma-ray bursts

    E-Print Network [OSTI]

    Kopac, D; Kobayashi, S; Virgili, F J; Harrison, R; Japelj, J; Guidorzi, C; Melandri, A; Gomboc, A

    2015-01-01

    We present predictions of centimeter and millimeter radio emission from reverse shocks in the early afterglows of gamma-ray bursts with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parametrization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. (2007) and Melandri et al. (2010) in which the typical frequency of the reverse shock was suggested to lie at radio, rather than optical wavelengths at early times, we show that the brightest and most distinct reverse-shock radio signatures are detectable up to 0.1 -- 1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later opt...

  20. Gamma Ray Fresnel lenses - why not?

    E-Print Network [OSTI]

    G. K. Skinner

    2006-02-03

    Fresnel lenses offer the possibility of concentrating the flux of X-rays or gamma-rays flux falling on a geometric area of many square metres onto a focal point which need only be a millimetre or so in diameter (and which may even be very much smaller). They can do so with an efficiency that can approach 100%, and yet they are easily fabricated and have no special alignment requirements. Fresnel lenses can offer diffraction-limited angular resolution, even in a domain where that limit corresponds to less than a micro second of arc. Given all these highly desirable attributes, it is natural to ask why Fresnel gamma ray lenses are not already being used, or at least why there is not yet any mission that plans to use the technology. Possible reasons (apart from the obvious one that nobody thought of doing so) include the narrow bandwidth of simple Fresnel lenses, their very long focal length, and the problems of target finding. It is argued that none of these is a "show stopper" and that this technique should be seriously considered for nuclear astrophysics.

  1. Characteristics of profiles of gamma-ray burst pulses associated with the Doppler effect of fireballs

    E-Print Network [OSTI]

    Yi-Ping Qin; Zhi-Bin Zhang; Fu-Wen Zhang; Xiao-Hong Cui

    2004-08-31

    In this paper, we derive in a much detail the formula of count rates, in terms of the integral of time, of gamma-ray bursts in the framework of fireballs, where the Doppler effect of the expanding fireball surface is the key factor to be concerned. Effects arising from the limit of the time delay due to the limited regions of the emitting areas in the fireball surface and other factors are investigated. Our analysis shows that the formula of the count rate of fireballs can be expressed as a function of $\\tau $ which is the observation time scale relative to the dynamical time scale of the fireball. The profile of light curves of fireballs depends only on the relative time scale, entirely independent of the real time scale and the real size of the objects. It displays in detail how a cutoff tail, or a turn over, feature (called a cutoff tail problem) in the decay phase of a light curve can be formed. This feature is a consequence of a hot spot in the fireball surface, moving towards the observer, and was observed in a few cases previously. By performing fits to the count rate light curves of six sample sources, we show how to obtain some physical parameters from the observed profile of the count rate of GRBs. In addition, the analysis reveals that the Doppler effect of fireballs could lead to a power law relationship between the $FWHM$ of pulses and energy, which were observed previously by many authors.

  2. Compton scattering effects on the duration of terrestrial gamma-ray flashes

    E-Print Network [OSTI]

    Pasko, Victor

    ; published 18 January 2012. [1] Terrestrial gamma-ray flashes (TGFs) are gamma-ray bursts detected from space) recently discovered by the gamma-ray burst monitor (GBM) aboard the Fermi Gamma-Ray Space Telescope. Introduction [2] Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from

  3. X-RAYRICH GAMMA-RAY BURSTS, PHOTOSPHERES, AND VARIABILITY P. Meszaros,1,2

    E-Print Network [OSTI]

    Zhang, Bing

    X-RAY­RICH GAMMA-RAY BURSTS, PHOTOSPHERES, AND VARIABILITY P. Me´sza´ros,1,2 E. Ramirez-Ruiz,3 M. J of the observational gamma-ray variability-luminosity relation. Subject headings: gamma rays: bursts -- radiation mechanisms: nonthermal 1. INTRODUCTION Gamma-ray burst (GRB) light curves at gamma-ray ener- gies are often

  4. A correlation between hard gamma-ray sources and cosmic voids along the line of sight

    SciTech Connect (OSTI)

    Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.

    2014-11-25

    We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4#27; level. There is also a less suggestive correlation for the Fermi hard source population (1.7#27;). A correlation between 10-500 GeV flux and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4#27; and 2.6#27;, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity #28;(E, z) #24; 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.

  5. A correlation between hard gamma-ray sources and cosmic voids along the line of sight

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.

    2014-11-25

    We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4? level. There is a less suggestive correlation for the Fermi hard source population (1.7?). A correlation between 10-500 GeV fluxmore »and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4? and 2.6?, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity ?(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.« less

  6. The Biggest Bangs The Mystery of Gamma-Ray Bursts,

    E-Print Network [OSTI]

    Katz, Jonathan I.

    . The Supernova Connection? 16. The Holy Grail 17. The End of the Beginning vii #12;· Afterword · Appendix. Did 16 The Holy Grail A few miles from Los Alamos, New Mexico, stands one of the most remark- able grail of gamma-ray burst astronomy for a quarter of a century. From the discovery of gamma-ray bursts

  7. THE BRIGHT GAMMA-RAY BURST OF 2000 FEBRUARY 10: A CASE STUDY OF AN OPTICALLY DARK GAMMA-RAY BURST

    E-Print Network [OSTI]

    Fynbo, Johan

    THE BRIGHT GAMMA-RAY BURST OF 2000 FEBRUARY 10: A CASE STUDY OF AN OPTICALLY DARK GAMMA-RAY BURST L Received 2002 January 16; accepted 2002 June 8 ABSTRACT The gamma-ray burst GRB 000210 had the highest: observations -- gamma-rays: bursts 1. INTRODUCTION It is observationally well established that about half

  8. PSR J1906+0722: An Elusive Gamma-ray Pulsar

    E-Print Network [OSTI]

    Clark, C J; Wu, J; Guillemot, L; Ackermann, M; Allen, B; de Angelis, A; Aulbert, C; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bellazzini, R; Bissaldi, E; Bock, O; Bonino, R; Bottacini, E; Brandt, T J; Bregeon, J; Bruel, P; Buson, S; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cecchi, C; Champion, D J; Charles, E; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cuéllar, A; Cutini, S; D'Ammando, F; Desiante, R; Drell, P S; Eggenstein, H B; Favuzzi, C; Fehrmann, H; Ferrara, E C; Focke, W B; Franckowiak, A; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guiriec, S; Harding, A K; Hays, E; Hewitt, J W; Hill, A B; Horan, D; Hou, X; Jogler, T; Johnson, A S; Jóhannesson, G; Kramer, M; Krauss, F; Kuss, M; Laffon, H; Larsson, S; Latronico, L; Li, J; Li, L; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Machenschalk, B; Manfreda, A; Marelli, M; Mayer, M; Mazziotta, M N; Michelson, P F; Mizuno, T; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nuss, E; Ohsugi, T; Orienti, M; Orlando, E; de Palma, F; Paneque, D; Pesce-Rollins, M; Piron, F; Pivato, G; Rainň, S; Rando, R; Razzano, M; Reimer, A; Parkinson, P M Saz; Schaal, M; Schulz, A; Sgrň, C; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Suson, D J; Takahashi, H; Thayer, J B; Tibaldo, L; Torne, P; Torres, D F; Tosti, G; Troja, E; Vianello, G; Wood, K S; Wood, M; Yassine, M

    2015-01-01

    We report the discovery of PSR J1906+0722, a gamma-ray pulsar detected as part of a blind survey of unidentified Fermi Large Area Telescope (LAT) sources being carried out on the volunteer distributed computing system, Einstein@Home. This newly discovered pulsar previously appeared as the most significant remaining unidentified gamma-ray source without a known association in the second Fermi-LAT source catalog (2FGL) and was among the top ten most significant unassociated sources in the recent third catalog (3FGL). PSR J1906+0722 is a young, energetic, isolated pulsar, with a spin frequency of $8.9$ Hz, a characteristic age of $49$ kyr, and spin-down power $1.0 \\times 10^{36}$ erg s$^{-1}$. In 2009 August it suffered one of the largest glitches detected from a gamma-ray pulsar ($\\Delta f / f \\approx 4.5\\times10^{-6}$). Remaining undetected in dedicated radio follow-up observations, the pulsar is likely radio-quiet. An off-pulse analysis of the gamma-ray flux from the location of PSR J1906+0722 revealed the pr...

  9. Constraining Lorentz violations with Gamma Ray Bursts

    E-Print Network [OSTI]

    Maria Rodriguez Martinez; Tsvi Piran

    2006-05-17

    Gamma ray bursts are excellent candidates to constrain physical models which break Lorentz symmetry. We consider deformed dispersion relations which break the boost invariance and lead to an energy-dependent speed of light. In these models, simultaneously emitted photons from cosmological sources reach Earth with a spectral time delay that depends on the symmetry breaking scale. We estimate the possible bounds which can be obtained by comparing the spectral time delays with the time resolution of available telescopes. We discuss the best strategy to reach the strongest bounds. We compute the probability of detecting bursts that improve the current bounds. The results are encouraging. Depending on the model, it is possible to build a detector that within several years will improve the present limits of 0.015 m_pl.

  10. Neutrino oscillations and gamma-ray bursts

    E-Print Network [OSTI]

    W. Kluzniak

    1998-07-22

    If the ordinary neutrinos oscillate into a sterile flavor in a manner consistent with the Super-Kamiokande data on the zenith-angle dependence of atmospheric mu-neutrino flux, an energy sufficient to power a typical cosmic gamma-ray burst (GRB) (about 10^{52} erg) can be carried by sterile neutrinos away from the source and deposited in a region relatively free of baryons. Hence, ultra-relativistic bulk motion (required by the theory of and observations of GRBs and their afterglows) can easily be achieved in the vicinity of plausible sources of GRBs. Oscillations between sterile and ordinary neutrinos would thus provide a solution to the ``baryon-loading problem'' in the theory of GRBs.

  11. Polarization mesurements of gamma ray bursts and axion like particles

    E-Print Network [OSTI]

    Andre Rubbia; Alexander Sakharov

    2008-09-03

    A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of axion like particles (ALPs). Based on evidences of polarized gamma ray emission detected in several gamma ray bursts we estimated the level of ALPs induced dichroism, which could take place in the magnetized fireball environment of a GRB. This allows to estimate the sensitivity of polarization measurements of GRBs to the ALP-photon coupling. This sensitivity $\\gag\\le 2.2\\cdot 10^{-11} {\\rm GeV^{-1}}$ calculated for the ALP mass $m_a=10^{-3}~{\\rm eV}$ and MeV energy spread of gamma ray emission is competitive with the sensitivity of CAST and becomes even stronger for lower ALPs masses.

  12. The supernova/gamma-ray burst/jet connection

    E-Print Network [OSTI]

    Hjorth, Jens

    2013-01-01

    The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bi-polar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star while the 56Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper I summarise the observational status of the supernova/gamma-ray burst connection in the context of the 'engine' picture of jet-driven supernovae and highlight SN 2012bz/GRB 120422A -- with its luminous supernova but intermediate high-energy luminosity -- as a possible transition object between low-luminosity and jet gamma-ray bursts. The jet channel for supernova explosions may provide new insight into supernova explosions in general.

  13. The Cosmic Gamma-Ray Bursts

    E-Print Network [OSTI]

    S. G. Djorgovski; D. A. Frail; S. R. Kulkarni; R. Sari; J. S. Bloom; T. J. Galama; F. A. Harrison; P. A. Price; D. Fox; D. Reichart; S. Yost; E. Berger; A. Diercks; R. Goodrich; F. Chaffee

    2001-06-29

    Cosmic gamma-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean gamma-ray energies after the beaming corrections are ~ 10^51 erg. Bursts are associated with faint ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host galaxies span a range of luminosities and morphologies, but appear to be broadly typical for the normal, actively star-forming galaxy populations at comparable redshifts and magnitudes. Some of the challenges for the future include: the nature of the short bursts and possibly other types of bursts and transients; use of GRBs to probe the obscured star formation in the universe, and possibly as probes of the very early universe; and their detection as sources of high-energy particles and gravitational waves.

  14. Magnetic Structures in Gamma-Ray Burst Jets Probed by Gamma-Ray Polarization

    E-Print Network [OSTI]

    Daisuke Yonetoku; Toshio Murakami; Shuichi Gunji; Tatehiro Mihara; Kenji Toma; Yoshiyuki Morihara; Takuya Takahashi; Yudai Wakashima; Hajime Yonemochi; Tomonori Sakashita; Noriyuki Toukairin; Hirofumi Fujimoto; Yoshiki Kodama

    2012-08-27

    We report polarization measurements in two prompt emissions of gamma-ray bursts, GRB 110301A and GRB 110721A, observed with the Gamma-ray burst polarimeter (GAP) aboard IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of $\\Pi = 70 \\pm 22$% with statistical significance of $3.7 \\sigma$ for GRB 110301A, and $\\Pi = 84^{+16}_{-28}$% with $3.3 \\sigma$ confidence level for GRB 110721A. We did not detect any significant change of polarization angle. These two events had shorter durations and dimmer brightness compared with GRB 100826A, which showed a significant change of polarization angle, as reported in Yonetoku et al. (2011). Synchrotron emission model can be consistent with all the data of the three GRBs, while photospheric quasi-thermal emission model is not favorable. We suggest that magnetic field structures in the emission region are globally-ordered fields advected from the central engine.

  15. MAGNETIC STRUCTURES IN GAMMA-RAY BURST JETS PROBED BY GAMMA-RAY POLARIZATION

    SciTech Connect (OSTI)

    Yonetoku, Daisuke; Murakami, Toshio; Morihara, Yoshiyuki; Takahashi, Takuya; Wakashima, Yudai; Yonemochi, Hajime; Sakashita, Tomonori; Fujimoto, Hirofumi; Kodama, Yoshiki [College of Science and Engineering, School of Mathematics and Physics, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192 (Japan); Gunji, Shuichi; Toukairin, Noriyuki [Department of Physics, Faculty of Science, Yamagata University, 1-4-12, Koshirakawa, Yamagata, Yamagata 990-8560 (Japan); Mihara, Tatehiro [Cosmic Radiation Laboratory, RIKEN, 2-1, Hirosawa, Wako City, Saitama 351-0198 (Japan); Toma, Kenji, E-mail: yonetoku@astro.s.kanazawa-u.ac.jp [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan)

    2012-10-10

    We report polarization measurements in two prompt emissions of gamma-ray bursts, GRB 110301A and GRB 110721A, observed with the gamma-ray burst polarimeter (GAP) on borad the IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of {Pi} = 70 {+-} 22% with statistical significance of 3.7{sigma} for GRB 110301A, and {Pi} = 84{sup +16}{sub -28}% with 3.3{sigma} confidence level for GRB 110721A. We did not detect any significant change of polarization angle. These two events had shorter durations and dimmer brightness compared with GRB 100826A, which showed a significant change of polarization angle, as reported in Yonetoku et al. Synchrotron emission model can be consistent with the data of the three GRBs, while the photospheric quasi-thermal emission model is not favored. We suggest that magnetic field structures in the emission region are globally ordered fields advected from the central engine.

  16. GRB 020410: A Gamma-ray burst afterglow discovered by its supernova light

    E-Print Network [OSTI]

    2004-01-01

    Training Network “Gamma-Ray Bursts: An Enigma and a Tool”,Journal GRB 020410: A Gamma-Ray Burst Afterglow DiscoveredSubject headings: gamma rays: bursts – supernova: general

  17. Compton Recoil Electron Tracking With the TIGRE Gamma-Ray Balloon Experiment

    E-Print Network [OSTI]

    Kamiya, Kaoru

    2011-01-01

    AGNs), pulsars, gamma-ray bursts, cosmic ray interactionssensitive to cosmic gamma-ray bursts in the energy range ofGalactic center, a single gamma-ray burst which occurred 10

  18. Search for muon neutrinos from Gamma-Ray Bursts with the IceCube neutrino telescope

    E-Print Network [OSTI]

    Abbasi, R.

    2010-01-01

    2009, GCN: The Gamma ray bursts Coordinates Network, http://for muon neutrinos from Gamma-Ray Bursts with the IceCubeMereghetti, S. 2004, in Gamma-ray Bursts: 30 Years of

  19. Long gamma-ray bursts and core-collapse supernovae have different environments

    E-Print Network [OSTI]

    2006-01-01

    V. et al. Host galaxies of gamma-ray bursts: Spectral energyal. Are the hosts of gamma-ray bursts sub-luminous and blueSupernova Light in Gamma- Ray Burst Afterglows. Astrophys.

  20. The Search for Muon Neutrinos from Northern Hemisphere Gamma-Ray Bursts with AMANDA

    E-Print Network [OSTI]

    Achterberg, A.; IceCube Collaboration

    2008-01-01

    see also the Swift Gamma-Ray Burst Mission Page: http://from Northern Hemisphere Gamma-Ray Bursts with AMANDA A.Northern Hemisphere Gamma-Ray Bursts with AMANDA The IceCube

  1. Exploring the Gamma Ray Horizon with the next generation of Gamma Ray Telescopes. Part 2: Extracting cosmological parameters from the observation of gamma-ray sources

    E-Print Network [OSTI]

    O. Blanch; M. Martinez

    2004-06-02

    The potential of the new generation Cherenkov Telescopes to measure the energy spectrum of both, the already established extragalactic very high energy gamma-ray emitters and the best very high energy candidates from the EGRET catalogue is discussed. By a realistic simulation of the analysis of the expected extrapolated energy spectra, it is shown that the foreseen capability and precision of these instrument to measure the Gamma Ray Horizon may open the door to competitive measurements of the cosmological parameters.

  2. Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope

    E-Print Network [OSTI]

    R. Atkins; W. Benbow; D. Berley; M. -L. Chen; D. G. Coyne; R. S. Delay; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; D. Evans; A. Falcone; L. Fleysher; R. Fleysher; G. Gisler; J. A. Goodman; T. J. Haines; C. M. Hoffman; S. Hugenberger; L. A. Kelley; I. Leonor; J. Macri; M. McConnell; J. F. McCullough; J. E. McEnery; R. S. Miller; A. I. Mincer; M. F. Morales; P. Nemethy; J. M. Ryan; M. Schneider; B. Shen; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; T. N. Thompson; O. T. Tumer; K. Wang; M. O. Wascko; S. Westerhoff; D. A. Williams; T. Yang; G. B. Yodh

    1999-06-24

    The Milagrito water Cherenkov telescope operated for over a year. The most probable gamma-ray energy was ~1 TeV and the trigger rate was as high as 400 Hz. We have developed an efficient technique for searching the entire sky for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts that were not in the field-of-view of any other instruments, the evaporation of primordial black holes, or some as yet undiscovered phenomenon. We have begun to search the Milagrito data set for bursts of duration 10 seconds. Here we will present the technique and the expected results. Final results will be presented at the conference.

  3. Search for Short Duration Bursts of TeV $\\gamma$ Rays with the Milagrito Telescope

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    1999-01-01

    The Milagrito water Cherenkov telescope operated for over a year. The most probable gamma-ray energy was ~1 TeV and the trigger rate was as high as 400 Hz. We have developed an efficient technique for searching the entire sky for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts that were not in the field-of-view of any other instruments, the evaporation of primordial black holes, or some as yet undiscovered phenomenon. We have begun to search the Milagrito data set for bursts of duration 10 seconds. Here we will present the technique and the expected results. Final results will be presented at the conference.

  4. Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir

    E-Print Network [OSTI]

    D. A. Frail; S. R. Kulkarni; R. Sari; S. G. Djorgovski; J. S. Bloom; T. J. Galama; D. E. Reichart; E. Berger; F. A. Harrison; P. A. Price; S. A. Yost; A. Diercks; R. W. Goodrich; F. Chaffee

    2001-02-15

    Gamma-ray bursts (GRBs) are the most brilliant objects in the Universe but efforts to estimate the total energy released in the explosion -- a crucial physical quantity -- have been stymied by their unknown geometry: spheres or cones. We report on a comprehensive analysis of GRB afterglows and derive their conical opening angles. We find that the gamma-ray energy release, corrected for geometry, is narrowly clustered around 5x10**50 erg. We draw three conclusions. First, the central engines of GRBs release energies that are comparable to ordinary supernovae, suggesting a connection. Second, the wide variation in fluence and luminosity of GRBs is due entirely to a distribution of opening angles. Third, only a small fraction of GRBs are visible to a given observer and the true GRB rate is at least a factor of 500 times larger than the observed rate.

  5. Gravitational waves versus X-ray and gamma-ray emission in a short gamma-ray burst

    SciTech Connect (OSTI)

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, R., E-mail: fe.fisica@gmail.com, E-mail: jorge.rueda@icra.it, E-mail: ruffini@icra.it [Dipartimento di Fisica and ICRA, Sapienza Universitŕ di Roma, P.le Aldo Moro 5, I-00185 Rome (Italy)

    2014-06-01

    Recent progress in the understanding of the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst (GRB), GRB 090227B, allows us to give an estimate of the gravitational waves versus the X-ray and gamma-ray emission in a short GRB.

  6. Constraints on Very High Energy gamma-ray emission from Gamma-Ray Bursts

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Blaufuss, E; Coyne, D G; De Young, T R; Dingus, B L; Dorfan, D E; Ellsworth, R W; Fleysher, L; Fleysher, R; González, M M; Goodman, J A; Hays, E; Hoffman, C M; Kelley, L A; Lansdell, C P; Linnemann, J T; McEnery, J E; Mincer, A I; Morales, M F; Némethy, P; Noyes, D; Ryan, J M; Samuelson, F W; Parkinson, P M S; Shoup, A; Sinnis, G; Smith, A J; Sullivan, G W; Williams, D A; Wilson, M E; Xu, X W; Yodh, G B

    2005-01-01

    The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high energy particles interacting in the Earth's atmosphere. Milagro has a wide field of view and high duty cycle, monitoring the northern sky almost continuously in the 100 GeV to 100 TeV energy range. Milagro is, thus, uniquely capable of searching for very high-energy emission from gamma-ray bursts (GRBs) during the prompt emission phase. Detection of >100 GeV counterparts would place powerful constraints on GRB mechanisms. Twenty-five satellite-triggered GRBs occurred within the field of view of Milagro between January 2000 and December 2001. We have searched for counterparts to these GRBs and found no significant emission from any of the burst positions. Due to the absorption of high-energy gamma rays by the extragalactic background light, detections are only expected to be possible for redshifts less than ~0.5. Three of the GRBs studied have measured redshifts. GRB 010921 has a redshift low ...

  7. Constraints on Very High Energy gamma-ray emission from Gamma-Ray Bursts

    E-Print Network [OSTI]

    R. Atkins; W. Benbow; D. Berley; E. Blaufuss; D. G. Coyne; T. DeYoung; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; L. Fleysher; R. Fleysher; M. M. Gonzalez; J. A. Goodman; E. Hays; C. M. Hoffman; L. A. Kelley; C. P. Lansdell; J. T. Linnemann; J. E. McEnery; A. I. Mincer; M. F. Morales; P. Nemethy; D. Noyes; J. M. Ryan; F. W. Samuelson; P. M. Saz Parkinson; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; D. A. Williams; M. E. Wilson; X. W. Xu; G. B. Yodh

    2005-03-11

    The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high energy particles interacting in the Earth's atmosphere. Milagro has a wide field of view and high duty cycle, monitoring the northern sky almost continuously in the 100 GeV to 100 TeV energy range. Milagro is, thus, uniquely capable of searching for very high-energy emission from gamma-ray bursts (GRBs) during the prompt emission phase. Detection of >100 GeV counterparts would place powerful constraints on GRB mechanisms. Twenty-five satellite-triggered GRBs occurred within the field of view of Milagro between January 2000 and December 2001. We have searched for counterparts to these GRBs and found no significant emission from any of the burst positions. Due to the absorption of high-energy gamma rays by the extragalactic background light, detections are only expected to be possible for redshifts less than ~0.5. Three of the GRBs studied have measured redshifts. GRB 010921 has a redshift low enough (0.45) to allow an upper limit on the fluence to place an observational constraint on potential GRB models.

  8. High Energy Gamma-Ray Emission from Gamma-Ray Bursts - Before GLAST

    SciTech Connect (OSTI)

    Fan, Yi-Zhong; Piran, Tsvi

    2011-11-29

    Gamma-ray bursts (GRBs) are short and intense emission of soft {gamma}-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high-energy {gamma}-ray emission (> 20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high-energy emission from GRBs. Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  9. Gamma-Ray Burst at the extreme: "the naked-eye burst" GRB 080319B

    E-Print Network [OSTI]

    P. R. Wozniak; W. T. Vestrand; A. D. Panaitescu; J. A. Wren; H. R. Davis; R. R. White

    2008-10-14

    On 19 March 2008, the northern sky was the stage of a spectacular optical transient that for a few seconds remained visible to the naked eye. The transient was associated with GRB 080319B, a gamma-ray burst at a luminosity distance of about 6 Gpc (standard cosmology), making it the most luminous optical object ever recorded by human kind. We present comprehensive sky monitoring and multi-color optical follow-up observations of GRB 080319B collected by the RAPTOR telescope network covering the development of the explosion and the afterglow before, during, and after the burst. The extremely bright prompt optical emission revealed features that are normally not detectable. The optical and gamma-ray variability during the explosion are correlated, but the optical flux is much greater than can be reconciled with single emission mechanism and a flat gamma-ray spectrum. This extreme optical behavior is best understood as synchrotron self-Compton model (SSC). After a gradual onset of the gamma-ray emission, there is an abrupt rise of the prompt optical flux suggesting that variable self-absorption dominates the early optical light curve. Our simultaneous multi-color optical light curves following the flash show spectral evolution consistent with a rapidly decaying red component due to large angle emission and the emergence of a blue forward shock component from interaction with the surrounding environment. While providing little support for the reverse shock that dominates the early afterglow, these observations strengthen the case for the universal role of the SSC mechanism in generating gamma-ray bursts.

  10. The 130 GeV gamma-ray line and generic dark matter model building constraints from continuum gamma rays, radio and antiproton data

    E-Print Network [OSTI]

    Masaki Asano; Torsten Bringmann; Gunter Sigl; Martin Vollmann

    2013-05-16

    An analysis of the Fermi gamma ray space telescope data has recently revealed a resolved gamma-ray feature close to the galactic center which is consistent with monochromatic photons at an energy of about 130 GeV. If interpreted in terms of dark matter (DM) annihilating into \\gamma\\gamma (\\gamma Z, \\gamma h), this would correspond to a DM particle mass of roughly 130 GeV (145 GeV, 155 GeV). The rate for these loop-suppressed processes, however, is larger than typically expected for thermally produced DM. Correspondingly, one would generically expect even larger tree level production rates of standard model fermions or gauge bosons. Here, we quantify this expectation in a rather model-independent way by relating the tree level and loop amplitudes with the help of the optical theorem. As an application, we consider bounds from continuum gamma rays, radio and antiproton data on the tree level amplitudes and translate them into constraints on the loop amplitudes. We find that, independently of the DM production mechanism, any DM model aiming at explaining the line signal in terms of charged standard model particles running in the loop is in rather strong tension with at least one of these constraints, with the exception of loops dominated by top quarks. We stress that attempts to explain the 130 GeV feature with internal bremsstrahlung do not suffer from such difficulties.

  11. The Evaluated Gamma-ray Activation File (EGAF)

    SciTech Connect (OSTI)

    Firestone, R. B. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Molnar, G. L.; Revay, Zs.; Belgya, T. [Institute of Isotope and Surface Chemistry, H-1525, Budapest (Hungary); McNabb, D. P.; Sleaford, B. W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2006-03-13

    The Evaluated Gamma-ray Activation File (EGAF), a new database of prompt and delayed neutron capture {gamma} ray cross sections, has been prepared as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project to develop a 'Database of Prompt Gamma-rays from Slow Neutron Capture for Elemental Analysis'. Recent elemental {gamma}-ray cross-section measurements performed with the guided neutron beam at the Budapest Reactor have been combined with data from the literature to produce the EGAF database. EGAF contains thermal cross sections for {approx_equal}35,000 prompt and delayed {gamma}-rays from 262 isotopes. New precise total thermal radiative cross sections have been derived for many isotopes from the primary and secondary gamma-ray cross sections and additional level scheme data. An IAEA TECDOC describing the EGAF evaluation and tabulating the most prominent {gamma}-rays will be published in 2004. The TECDOC will include a CD-ROM containing the EGAF database in both ENSDF and tabular formats with an interactive viewer for searching and displaying the data. The Isotopes Project, Lawrence Berkeley National Laboratory continues to maintain and update the EGAF file. These data are available on the Internet from both the IAEA and Isotopes Project websites.

  12. Gamma Ray Burst Constraints on Ultraviolet Lorentz Invariance Violation

    E-Print Network [OSTI]

    Tina Kahniashvili; Grigol Gogoberidze; Bharat Ratra

    2006-10-20

    We present a unified general formalism for ultraviolet Lorentz invariance violation (LV) testing through electromagnetic wave propagation, based on both dispersion and rotation measure data. This allows for a direct comparison of the efficacy of different data to constrain LV. As an example we study the signature of LV on the rotation of the polarization plane of $\\gamma$-rays from gamma ray bursts in a LV model. Here $\\gamma$-ray polarization data can provide a strong constraint on LV, 13 orders of magnitude more restrictive than a potential constraint from the rotation of the cosmic microwave background polarization proposed by Gamboa, L\\'{o}pez-Sarri\\'{o}n, and Polychronakos (2006).

  13. A Search for Gamma-Ray Bursts and Pulsars, and the Application of Kalman Filters to Gamma-Ray Reconstruction

    E-Print Network [OSTI]

    B. B. Jones

    2002-02-04

    Part I describes the analysis of periodic and transient signals in EGRET data. A method to search for the transient flux from gamma-ray bursts independent of triggers from other gamma-ray instruments is developed. Several known gamma-ray bursts were independently detected, and there is evidence for a previously unknown gamma-ray burst candidate. Statistical methods using maximum likelihood and Bayesian inference are developed and implemented to extract periodic signals from gamma-ray sources in the presence of significant astrophysical background radiation. The analysis was performed on six pulsars and three pulsar candidates. The three brightest pulsars, Crab, Vela, and Geminga, were readily identified, and would have been detected independently in the EGRET data without knowledge of the pulse period. No significant pulsation was detected in the three pulsar candidates. Eighteen X-ray binaries were examined. None showed any evidence of periodicity. In addition, methods for calculating the detection threshold of periodic flux modulation were developed. The future hopes of gamma-ray astronomy lie in the development of the Gamma-ray Large Area Space Telescope, or GLAST. Part II describes the development and results of the particle track reconstruction software for a GLAST science prototype instrument beam test. The Kalman filtering method of track reconstruction is introduced and implemented. Monte Carlo simulations, very similar to those used for the full GLAST instrument, were performed to predict the instrumental response of the prototype. The prototype was tested in a gamma-ray beam at SLAC. The reconstruction software was used to determine the incident gamma-ray direction. It was found that the simulations did an excellent job of representing the actual instrument response.

  14. The electromagnetic model of Gamma Ray Bursts

    E-Print Network [OSTI]

    Maxim Lyutikov

    2005-12-13

    I describe electromagnetic model of gamma ray bursts and contrast its main properties and predictions with hydrodynamic fireball model and its magnetohydrodynamical extension. The electromagnetic model assumes that rotational energy of a relativistic, stellar-mass central source (black-hole--accretion disk system or fast rotating neutron star) is converted into magnetic energy through unipolar dynamo mechanism, propagated to large distances in a form of relativistic, subsonic, Poynting flux-dominated wind and is dissipated directly into emitting particles through current-driven instabilities. Thus, there is no conversion back and forth between internal and bulk energies as in the case of fireball model. Collimating effects of magnetic hoop stresses lead to strongly non-spherical expansion and formation of jets. Long and short GRBs may develop in a qualitatively similar way, except that in case of long bursts ejecta expansion has a relatively short, non-relativistic, strongly dissipative stage inside the star. Electromagnetic and fireball models (as well as strongly and weakly magnetized fireballs) lead to different early afterglow dynamics, before deceleration time. Finally, I discuss the models in view of latest observational data in the Swift era.

  15. Blueshifting may explain the gamma ray bursts

    E-Print Network [OSTI]

    Krasi?ski, Andrzej

    2015-01-01

    It is shown that the basic observed properties of the gamma-ray bursts (GRBs) are accounted for if one assumes that the GRBs arise by blueshifting the emission radiation of hydrogen and helium generated during the last scattering epoch. The blueshift generator for a single GRB is a Lema\\^{\\i}tre -- Tolman (L--T) region with a nonconstant bang-time function $t_B(r)$ matched into a Friedmann background. Blueshift visible to the observer arises \\textit{only on radial rays} that are emitted in the L--T region. The paper presents three L--T models with different Big Bang profiles, adapted for the highest and the lowest end of the GRB frequency range. The models account for: (1) The observed frequency range of the GRBs; (2) Their limited duration; (3) The afterglows; (4) Their hypothetical collimation into narrow jets; (5) The large distances to their sources; (6) The multitude of the observed GRBs. Properties (2), (3) and (6) are accounted for only qualitatively. With a small correction of the parameters of the mo...

  16. Discovery of TeV Gamma-Ray Emission from the Cygnus Region of the Galaxy

    E-Print Network [OSTI]

    A. A. Abdo; B. Allen; D. Berley; E. Blaufuss; S. Casanova; C. Chen; D. G. Coyne; R. S. Delay; B. L. Dingus; R. W. Ellsworth; L. Fleysher; R. Fleysher; M. M. Gonzalez; J. A. Goodman; E. Hays; C. M. Hoffman; B. E. Kolterman; L. A. Kelley; C. P. Lansdell; J. T. Linnemann; J. E. McEnery; A. I. Mincer; I. V. Moskalenko; P. Nemethy; D. Noyes; J. M. Ryan; F. W. Samuelson; P. M. Saz Parkinson; M. Schneider; A. Shoup; G. Sinnis; A. J. Smith; A. W. Strong; G. W. Sullivan; V. Vasileiou; G. P. Walker; D. A. Williams; X. W. Xu; G. B. Yodh

    2006-11-21

    The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at ~12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or other sources of TeV gamma rays in the region.

  17. Fermi-LAT Discovery of GeV Gamma-ray Emission from the Young Supernova Remnant Cassiopeia A

    SciTech Connect (OSTI)

    Abdo, A.A.

    2011-08-19

    We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2{sigma} above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation - Cassiopeia A. The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W{sub CR} {approx_equal} (1-4) x 10{sup 49} erg thanks to the well-known density in the remnant assuming that the observed gamma-ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B {ge} 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

  18. Gravitational waves from gamma-ray pulsar glitches

    SciTech Connect (OSTI)

    Stopnitzky, Elan; Profumo, Stefano

    2014-06-01

    We use data from pulsar gamma-ray glitches recorded by the Fermi Large Area Telescope as input to theoretical models of gravitational wave signals the glitches might generate. We find that the typical peak amplitude of the gravity wave signal from gamma-ray pulsar glitches lies between 10{sup –23} and 10{sup –35} in dimensionless units, with peak frequencies in the range of 1 to 1000 Hz, depending on the model. We estimate the signal-to-noise ratio (S/N) for all gamma-ray glitches, and discuss detectability with current gravity wave detectors. Our results indicate that the strongest predicted signals are potentially within reach of current detectors, and that pulsar gamma-ray glitches are promising targets for gravity wave searches by current and next-generation detectors.

  19. Redshifts of the Long Gamma-Ray Bursts

    E-Print Network [OSTI]

    Z. Bagoly; I. Csabai; A. Meszaros; P. Meszaros; I. Horvath; L. G. Balazs; R. Vavrek

    2007-04-06

    The low energy spectra of some gamma-ray bursts' show excess components beside the power-law dependence. The consequences of such a feature allows to estimate the gamma photometric redshift of the long gamma-ray bursts in the BATSE Catalog. There is good correlation between the measured optical and the estimated gamma photometric redshifts. The estimated redshift values for the long bright gamma-ray bursts are up to z=4, while for the the faint long bursts - which should be up to z=20 - the redshifts cannot be determined unambiguously with this method. The redshift distribution of all the gamma-ray bursts with known optical redshift agrees quite well with the BATSE based gamma photometric redshift distribution.

  20. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    Vanderspek, Roland K.

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified ...

  1. Status of space-based gamma-ray astronomy

    E-Print Network [OSTI]

    Buehler, Rolf

    2015-01-01

    Gamma-ray observations give us a direct view into the most extreme environments of the universe. They help us to study astronomical particle accelerators as supernovae remnants, pulsars, active galaxies or gamma-ray bursts and help us to understand the propagation of cosmic rays through our Milky Way. This article summarizes the status of gamma-ray observations from space; it is the write-up of a rapporteur talk given at the 34th ICRC in The Hague, The Netherlands. The primary instrument used in the presented studies is the Large Area Telescope on-board the Fermi Spacecraft, which images the whole gamma-ray sky at photon energies between 20 MeV and 2 TeV. The Fermi mission is currently in its 8th year of observations. This article will review many of the exciting discoveries made in this time, focusing on the most recent ones.

  2. Hyperstars - Main Origin of Short Gamma Ray Bursts?

    E-Print Network [OSTI]

    Arnon Dar

    2005-09-09

    The first well-localized short-duration gamma ray bursts (GRBs), GRB 050509b, GRB 050709 and GRB 050724, could have been the narrowly beamed initial spike of a burst/hyper flare of soft gamma ray repeaters (SGRs) in host galaxies at cosmological distances. Such bursts are expected if SGRs are young hyperstars, i.e. neutron stars where a considerable fraction of their neutrons have converted to hyperons and/or strange quark matter.

  3. Gamma Ray Bursts as Probes of Quantum Gravity

    E-Print Network [OSTI]

    Tsvi Piran

    2004-07-21

    Gamma ray bursts (GRBs) are short and intense pulses of $\\gamma$-rays arriving from random directions in the sky. Several years ago Amelino-Camelia et al. pointed out that a comparison of time of arrival of photons at different energies from a GRB could be used to measure (or obtain a limit on) possible deviations from a constant speed of light at high photons energies. I review here our current understanding of GRBs and reconsider the possibility of performing these observations.

  4. THE SWIFT GAMMA-RAY BURST MISSION N. Gehrels,1

    E-Print Network [OSTI]

    Smith, Ian Andrew

    THE SWIFT GAMMA-RAY BURST MISSION N. Gehrels,1 G. Chincarini,2,3 P. Giommi,4 K. O. Mason,5 J. A. E. Marshall,1 P. Me´sza´ros,6 P. W. A. Roming,6 L. Angelini,1,10 L. M. Barbier,1 T. Belloni,2 S The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB

  5. The University of Durham Mark 6 VHE gamma ray telescope

    SciTech Connect (OSTI)

    Chadwick, P. M.; Dickinson, M. R.; Dipper, N. A.; Holder, J.; Kendall, T. R.; McComb, T. J. L.; Orford, K. J.; Rayner, S. M.; Roberts, I. D.; Shaw, S. E.; Turver, K. E.

    1997-05-10

    The operation of the University of Durham Mark 6 atmospheric Cerenkov telescope is discussed. The telescope has been used to detect gamma rays at energies {>=}150 GeV and to achieve good discrimination between gamma ray and hadron initiated showers, using both conventional imaging and novel fluctuation measures. The telescope was commissioned in 1995 and a description of its operation is presented. Verification of the performance during observations of PSR B1706-44 is described.

  6. Science with the new generation high energy gamma- ray experiments

    E-Print Network [OSTI]

    Alvarez, M; Agnetta, G; Alberdi, A; Antonelli, A; Argan, A; Assis, P; Baltz, E A; Bambi, C; Barbiellini, G; Bartko, H; Basset, M; Bastieri, D; Belli, P; Benford, G; Bergström, L; Bernabei, R; Bertone, G; Biland, A; Biondo, B; Bocchino, F; Branchini, E; Brigida, M; Bringmann, T; Brogueira, P; Bulgarelli, A; Caballero, J A; Caliandro, G A; Camarri, P; Cappella, F; Caraveo, P; Carbone, R; Carvajal, M; Casanova, S; Castro-Tirado, A J; Catalano, O; Catena, R; Celi, F; Celotti, A; Cerulli, R; Chen, A; Clay, R; Cocco, V; Conrad, J; Costa, E; Cuoco, A; Cusumano, G; Dai, C J; Dawson, B; De Lotto, B; De Paris, G; Postigo, A de Ugarte; Del Monte, E; Delgado, C; Di Ciaccio, A; Di Cocco, G; Di Falco, S; Di Persio, G; Dingus, B L; Dominguez, A; Donato, F; Donnarumma, I; Doro, M; Edsjö, J; Navas, J M Espino; Santo, M C Espirito; Evangelista, Y; Evoli, C; Fargion, D; Favuzzi, C; Feroci, M; Fiorini, M; Foggetta, L; Fornengo, N; Froysland, T; Frutti, M; Fuschino, F; Gómez, J L; Gómez, M; Gaggero, D; Galante, N; Gallardo, M I; Galli, M; García, J E; Garczarczyk, M; Gargano, F; Gaug, M; Gianotti, F; Giarrusso, S; Giebels, B; Giglietto, N; Giommi, P; Giordano, F; Giuliani, A; Glicenstein, J; Gonçalves, P; Grasso, D; Guerriero, M; He, H L; Incicchitti, A; Kirk, J; Kuang, H H; La Barbera, A; La Rosa, G; Labanti, C; Lamanna, G; Lapshov, I; Lazzarotto, F; Liberati, S; Liello, F; Lipari, P; Longo, F; Loparco, F; Lozano, M; De Sanctis, P G Lucentini; Ma, J M; Maccarone, M C; Maccione, L; Malvezzi, V; Mangano, A; Mariotti, M; Marisaldi, M; Martel, I; Masiero, A; Massaro, E; Mastropietro, M; Mattaini, E; Mauri, F; Mazziotta, M N; Mereghetti, S; Mineo, T; Mizobuchi, S; Moiseev, A; Moles, M; Monte, C; Montecchia, F; Morelli, E; Morselli, A; Moskalenko, I; Nozzoli, F; Ormes, J F; Peres-Torres, M A; Pacciani, L; Pellizzoni, A; Pérez-Bernal, F; Perotti, F; Picozza, P; Pieri, L; Pietroni, M; Pimenta, M; Pina, A; Pittori, C; Pontoni, C; Porrovecchio, G; Prada, F; Prest, M; Prosperi, D; Protheroe, R; Pucella, G; Quesada, J M; Quintana, J M; Quintero, J R; Rainó, S; Rapisarda, M; Rissi, M; Rodríguez, J; Rossi, E; Rowell, G; Rubini, A; Russo, F; Sanchez-Conde, M; Sacco, B; Scapin, V; Schelke, M; Segreto, A; Sellerholm, A; Sheng, X D; Smith, A; Soffitta, P; Sparvoli, R; Spinelli, P; Stamatescu, V; Stark, L S; Tavani, M; Thornton, G; Titarchuk, L G; Tomé, B; Traci, A; Trifoglio, M; Trois, A; Vallania, P; Vallazza, E; Vercellone, S; Vernetto, S; Vitale, V; Wild, N; Ye, Z P; Zambra, A; Zandanel, F; Zanello, D

    2007-01-01

    This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006. This year the focus was on the use of gamma-ray to study the Dark Matter component of the Universe, the origin and propagation of Cosmic Rays, Extra Large Spatial Dimensions and Tests of Lorentz Invariance.

  7. A Directional Gamma-Ray Detector Based on Scintillator Plates

    E-Print Network [OSTI]

    Hanna, D; Boyle, P; MacLeod, A M L

    2015-01-01

    A simple device for determining the azimuthal location of a source of gamma radiation, using ideas from astrophysical gamma-ray burst detection, is described. A compact and robust detector built from eight identical modules, each comprising a plate of CsI(Tl) scintillator coupled to a photomultiplier tube, can locate a point source of gamma rays with degree-scale precision by comparing the count rates in the different modules. Sensitivity to uniform environmental background is minimal.

  8. Relativity at Action or Gamma-Ray Bursts

    E-Print Network [OSTI]

    Tsvi Piran

    1996-07-08

    Gamma ray Bursts (GRBs) - short bursts of few hundred keV $\\gamma$-rays - have fascinated astronomers since their accidental discovery in the sixties. GRBs were ignored by most relativists who did not expect that they are associated with any relativistic phenomenon. The recent observations of the BATSE detector on the Compton GRO satellite have revolutionized our ideas on these bursts and the picture that emerges shows that GRBs are the most relativistic objects discovered so far.

  9. Ivan De Mitri VHE Gamma Ray Astronomy 1 Very High Energy

    E-Print Network [OSTI]

    Harrison, Thomas

    ~ 1/day Gamma Ray Bursts The X-ray counterpart detection with better pointing accuracy instrumentsIvan De Mitri VHE Gamma Ray Astronomy 1 Very High Energy Gamma Ray Astronomy Ivan De Mitri'Aquila, 11- Jun -2002 Photo F. Arneodo #12;Ivan De Mitri VHE Gamma Ray Astronomy 2 Seminar Outline Background

  10. Radio emissions from terrestrial gamma-ray flashes Joseph R. Dwyer1

    E-Print Network [OSTI]

    Cummer, Steven A.

    . Introduction 1.1. TGF Theory Overview [2] Terrestrial gamma-ray flashes (TGFs) are bright bursts of gamma raysRadio emissions from terrestrial gamma-ray flashes Joseph R. Dwyer1 and Steven A. Cummer2 Received frequency (RF) emissions by terrestrial gamma-ray flashes (TGFs) is developed. These radio emissions, which

  11. Results from the Milagro Gamma-Ray Observatory E. Blaufuss a

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    V emission from the galactic plane, and a search for transient emission above 100 GeV from gamma ray bursts- clei (AGN), supernova remnants and gamma-ray bursts (GRB). Gamma rays are also produced when high1 Results from the Milagro Gamma-Ray Observatory E. Blaufuss a for the Milagro Collaboration

  12. Measurements and implications of the relationship between lightning and terrestrial gamma ray flashes

    E-Print Network [OSTI]

    Cummer, Steven A.

    the discovery of short bursts of gamma rays originating from Earth, called terrestrial gamma ray flashes (TGFsMeasurements and implications of the relationship between lightning and terrestrial gamma ray associated with 26 terrestrial gamma ray flashes (TGFs) recorded by the RHESSI satellite over the Caribbean

  13. MILAGRO CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM SHORT-DURATION GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    MILAGRO CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM SHORT-DURATION GAMMA-RAY BURSTS A. A. Abdo,1 localizations of short, hard gamma-ray bursts (GRBs) by the Swift and HETE satellites have led: bursts -- gamma rays: observations Gamma-ray bursts (GRBs) have long been classified by their durations

  14. CORRELATIONS OF PROMPT AND AFTERGLOW EMISSION IN SWIFT LONG AND SHORT GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    Zhang, Bing

    CORRELATIONS OF PROMPT AND AFTERGLOW EMISSION IN SWIFT LONG AND SHORT GAMMA-RAY BURSTS N. Gehrels,1 of prompt and afterglow emission from gamma-ray bursts (GRBs) between different spectral bands have been-limited for long events. Subject headingg: gamma rays: bursts 1. INTRODUCTION One of the longest enduring gamma-ray

  15. Gamma Ray Bursts as seen by a Giant Air Shower Array

    E-Print Network [OSTI]

    C. O. Escobar; P. L. Da Silva; R. A. Vázquez

    1997-12-19

    The potentiality of a Giant Shower Array to low energy gamma rays from gamma ray bursts is discussed. Effective areas are calculated for different scenarios and the results are encouraging. If gamma ray bursts have a spectrum which continues in the high energy gamma ray region, the Pierre Auger Observatory will be able to detect it.

  16. Gamma-ray emission from binaries in context

    E-Print Network [OSTI]

    Dubus, Guillaume

    2015-01-01

    More than a dozen binary systems are now established as sources of variable, high energy (HE, 0.1-100 GeV) gamma rays. Five are also established sources of very high energy (VHE, >100 GeV) gamma rays. The mechanisms behind gamma-ray emission in binaries are very diverse. My current understanding is that they divide up into four types of systems: gamma-ray binaries, powered by pulsar rotation; microquasars, powered by accretion onto a black hole or neutron star; novae, powered by thermonuclear runaway on a white dwarf; colliding wind binaries, powered by stellar winds from massive stars. Some of these types had long been suspected to emit gamma rays (microquasars), others have taken the community by surprise (novae). My purpose here is to provide a brief review of the current status of gamma-ray emission from binaries, in the context of related objects where similar mechanisms are at work (pulsar wind nebulae, active galactic nuclei, supernova remnants).

  17. Gamma-ray Albedo of Small Solar System Bodies

    SciTech Connect (OSTI)

    Moskalenko, I.V.

    2008-03-25

    We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and KBOs strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected, it can be used to derive the mass spectrum of small bodies in the Main Belt and Kuiper Belt and to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center. For details of our calculations and references see [1].

  18. Neutrino and cosmic-ray emission from multiple internal shocks in gamma-ray bursts

    E-Print Network [OSTI]

    Mauricio Bustamante; Philipp Baerwald; Kohta Murase; Walter Winter

    2015-10-14

    Gamma-ray bursts are short-lived, luminous explosions at cosmological distances, thought to originate from relativistic jets launched at the deaths of massive stars. They are among the prime candidates to produce the observed cosmic rays at the highest energies. Recent neutrino data have, however, started to constrain this possibility in the simplest models with only one emission zone. In the classical theory of gamma-ray bursts, it is expected that particles are accelerated at mildly relativistic shocks generated by the collisions of material ejected from a central engine. We consider neutrino and cosmic-ray emission from multiple emission regions since these internal collisions must occur at very different radii, from below the photosphere all the way out to the circumburst medium, as a consequence of the efficient dissipation of kinetic energy. We demonstrate that the different messengers originate from different collision radii, which means that multi-messenger observations open windows for revealing the evolving GRB outflows.

  19. Compton scattering in terrestrial gamma-ray flashes detected with the Fermi gamma-ray burst monitor

    E-Print Network [OSTI]

    Fitzpatrick, Gerard; McBreen, Sheila; Briggs, Michael S; Foley, Suzanne; Tierney, David; Chaplin, Vandiver L; Connaughton, Valerie; Stanbro, Matthew; Xiong, Shaolin; Dwyer, Joseph; Fishman, Gerald J; Roberts, Oliver J; von Kienlin, Andreas

    2015-01-01

    Terrestrial gamma-ray flashes (TGFs) are short intense flashes of gamma rays associated with lightning activity in thunderstorms. Using Monte Carlo simulations of the relativistic runaway electron avalanche (RREA) process, theoretical predictions for the temporal and spectral evolution of TGFs are compared to observations made with the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Assuming a single source altitude of 15 km, a comparison of simulations to data is performed for a range of empirically chosen source electron variation time scales. The data exhibit a clear softening with increased source distance, in qualitative agreement with theoretical predictions. The simulated spectra follow this trend in the data, but tend to underestimate the observed hardness. Such a discrepancy may imply that the basic RREA model is not sufficient. Alternatively, a TGF beam that is tilted with respect to the zenith could produce an evolution with source distance that is compatible with the da...

  20. Cluster of Gamma-ray Bursts - Image of a Source. Catalog of Clusters (Sources) of Gamma-ray Bursts

    E-Print Network [OSTI]

    A. V. Kuznetsov

    2001-11-01

    The clusters of gamma-ray bursts are considered which are assumed to be images of the repeated gamma-ray burst (GRB) sources. It is shown, that localization of the cosmic gamma-ray burst sources (GBS) is determined by the clusters of GRBs. About 100 candidates in sources are presented in the form of the catalog, which is compiled relying on the base of the BATSE data up to middle of 2000. Gamma-ray bursts (from 5 to 13) of a cluster that display a source do not coincide in their position. The catalog table containing basic information about the GRB sources yields the possibility to research the GBS properties and their identification. The birth of GRBs in the clusters allows predicting the appearance of GRBs both in time and space. Most general properties of the supposed GRB sources are discussed. An attempt to compile the first GRB source catalog is made.

  1. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Norris, Jay P. [Physics and Astronomy Department, University of Denver, Denver, CO 80208 (United States); Gehrels, Neil [Astroparticle Physics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Scargle, Jeffrey D. [Space Science and Astrobiology Division, NASA/Ames Research Center, Moffett Field, CA 94035-1000 (United States)

    2011-07-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample is comprised of 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales-durations, pulse structure widths, and peak intervals-for EE bursts are factors of {approx}2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts-the anti-correlation of pulse intensity and width-continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition, we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/X-Ray Telescope (XRT). The median flux of the initial XRT detections for EE bursts ({approx}6x10{sup -10} erg cm{sup -2} s{sup -1}) is {approx}>20x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts ({approx}60,000 s) is {approx}30x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into denser environments than non-EE bursts, or that the sometimes-dominant EE component efficiently powers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  2. Nanolensing of gamma-ray bursts

    E-Print Network [OSTI]

    Mark A. Walker; Geraint F. Lewis

    2003-02-10

    All quasars vary in their optical flux on a time-scale of years, and it has been proposed that these variations are principally due to gravitational lensing by a cosmologically distributed population of planetary mass objects. This interpretation has implications for the observable properties of gamma-ray bursts (GRBs) -- as a source expands across the nano-arcsecond caustic network, variability is expected -- and data on GRBs can be used to test the proposed model of quasar variability. Here we employ an ultra-relativistic blast-wave model of the source, with no intrinsic variations, to study the effects of nanolensing on GRBs. Taken in isolation the light-curves of the caustic crossings are predictable, and we find that a subset of the predicted light-curves (the image-annihilating fold crossings) resemble the ``pulses'' which are commonly seen in long GRBs. Furthermore, for sources at high redshift the expected time between caustic crossings is of order seconds, comparable to the observed time between pulses. These points suggest that it might be possible to model some of the observed variations of GRBs in terms of nanolensing; however, our simulated light-curves exhibit a small depth of modulation compared to what is observed. This means that the GRB data do not significantly constrain the quasar nanolensing model; it also means that the simplest nanolensing model cannot explain the observed GRB ``pulses''. Viable nanolensing models for pulses probably require a large external beam shear. If a viable model can be constructed it would effect a considerable simplification in source modelling and, ironically, it would explain why no macro-lensed GRBs have been identified to date. (Abridged)

  3. Time-of-flight discrimination between gamma-rays and neutrons by neural networks

    E-Print Network [OSTI]

    Serkan Akkoyun

    2012-08-13

    In gamma-ray spectroscopy, a number of neutrons are emitted from the nuclei together with the gamma-rays and these neutrons influence gamma-ray spectra. An obvious method of separating between neutrons and gamma-rays is based on the time-of-flight (tof) technique. This work aims obtaining tof distributions of gamma-rays and neutrons by using feed-forward artificial neural network (ANN). It was shown that, ANN can correctly classify gamma-ray and neutron events. Testing of trained networks on experimental data clearly shows up tof discrimination of gamma-rays and neutrons.

  4. Testing the millisecond pulsar scenario of the Galactic center gamma-ray excess with very high energy gamma-rays

    E-Print Network [OSTI]

    Qiang Yuan; Kunihito Ioka

    2015-02-09

    The recent analyses of the Fermi Large Area Telescope data show an extended GeV $\\gamma$-ray excess on top of the expected diffuse background in the Galactic center region, which can be explained with annihilating dark matter or a population of millisecond pulsars (MSPs). We propose to observe the very high energy $\\gamma$-rays for distinguishing the MSP scenario from the dark matter scenario. The GeV $\\gamma$-ray MSPs should release most energy to the relativistic $e^{\\pm}$ wind, which will diffuse in the Galaxy and radiate TeV $\\gamma$-rays through inverse Compton scattering and bremsstrahlung processes. By calculating the spectrum and spatial distribution, we show that such emission is detectable with the next generation very high energy $\\gamma$-ray observatory, the Cherenkov Telescope Array (CTA), under reasonable model parameters. It is essential to search for the multi-wavelength counterparts to the GeV $\\gamma$-ray excess for solving this mystery in the high energy universe.

  5. TEMPORAL DECONVOLUTION STUDY OF LONG AND SHORT GAMMA-RAY BURST LIGHT CURVES

    SciTech Connect (OSTI)

    Bhat, P. N.; Briggs, Michael S.; Connaughton, Valerie; Paciesas, William; Burgess, Michael; Chaplin, Vandiver; Goldstein, Adam; Guiriec, Sylvain [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Kouveliotou, Chryssa; Fishman, Gerald [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, Alexander J.; Meegan, Charles A. [Center for Space Plasma and Aeronomic Research (CSPAR), Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Bissaldi, Elisabetta [Institute of Astro and Particle Physics, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Diehl, Roland; Foley, Suzanne; Greiner, Jochen; Gruber, David [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Fitzpatrick, Gerard [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); Gibby, Melissa; Giles, Misty M. [Jacobs Technology, Inc., Huntsville, AL 35806 (United States); and others

    2012-01-10

    The light curves of gamma-ray bursts (GRBs) are believed to result from internal shocks reflecting the activity of the GRB central engine. Their temporal deconvolution can reveal potential differences in the properties of the central engines in the two populations of GRBs which are believed to originate from the deaths of massive stars (long) and from mergers of compact objects (short). We present here the results of the temporal analysis of 42 GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope. We deconvolved the profiles into pulses, which we fit with lognormal functions. The distributions of the pulse shape parameters and intervals between neighboring pulses are distinct for both burst types and also fit with lognormal functions. We have studied the evolution of these parameters in different energy bands and found that they differ between long and short bursts. We discuss the implications of the differences in the temporal properties of long and short bursts within the framework of the internal shock model for GRB prompt emission.

  6. Gamma-Ray Bursts from Radio-Quiet Quasars

    E-Print Network [OSTI]

    N. Schartel; H. Andernach; J. Greiner

    1996-12-16

    We study positional coincidences between gamma-ray bursts in the BATSE 3B catalogue and quasars/AGN taken from the Veron-Cetty & Veron compilation. For most classes of AGN, for BL Lac objects and for radio-loud quasars, we find no excess coincidences above random expectation, and we give upper limits for their burst emission rate. However, surprising evidence is found for a positional correlation between gamma-ray bursts and radio-quiet quasars. A total of 134 selected bursts with a position error radius 99.7% to be associated with each other. An analysis of a smaller sample of well-localized interplanetary network gamma-ray burst positions supports this result. This correlation strongly favours the cosmological origin of gamma-ray bursts and enables to estimate its distance scale. The average luminosity of those gamma-ray bursts which we associate directly with radio-quiet quasars is of the order of 4*10^52 erg (assuming isotropic emission).

  7. TANAMI: Milliarcsecond Resolution Observations of Extragalactic Gamma-ray Sources

    E-Print Network [OSTI]

    Ojha, Roopesh; Böck, M; Booth, R; Dutka, M S; Edwards, P G; Fey, A L; Fuhrmann, L; Gaume, R A; Hase, H; Horiuchi, S; Jauncey, D L; Johnston, K J; Katz, U; Lister, M; Lovell, J E J; Müller, C; Plötz, C; Quick, J F H; Ros, E; Taylor, G B; Thompson, D J; Tingay, S J; Tosti, G; Tzioumis, A K; Wilms, J; Zensus, J A

    2010-01-01

    The TANAMI (Tracking AGN with Austral Milliarcsecond Interferometry) and associated programs provide comprehensive radio monitoring of extragalactic gamma-ray sources south of declination -30 degrees. Joint quasi-simultaneous observations between the Fermi Gamma-ray Space Telescope and ground based observatories allow us to discriminate between competing theoretical blazar emission models. High resolution VLBI observations are the only way to spatially resolve the sub-parsec level emission regions where the high-energy radiation originates. The gap from radio to gamma-ray energies is spanned with near simultaneous data from the Swift satellite and ground based optical observatories. We present early results from the TANAMI program in the context of this panchromatic suite of observations.

  8. Exploring Particle Acceleration in Gamma-Ray Binaries

    E-Print Network [OSTI]

    Bosch-Ramon, V

    2011-01-01

    Binary systems can be powerful sources of non-thermal emission from radio to gamma rays. When the latter are detected, then these objects are known as gamma-ray binaries. In this work, we explore, in the context of gamma-ray binaries, different acceleration processes to estimate their efficiency: Fermi I, Fermi II, shear acceleration, the converter mechanism, and magnetic reconnection. We find that Fermi I acceleration in a mildly relativistic shock can provide, although marginally, the multi-10 TeV particles required to explain observations. Shear acceleration may be a complementary mechanism, giving particles the final boost to reach such a high energies. Fermi II acceleration may be too slow to account for the observed very high energy photons, but may be suitable to explain extended low-energy emission. The converter mechanism seems to require rather high Lorentz factors but cannot be discarded a priori. Standard relativistic shock acceleration requires a highly turbulent, weakly magnetized downstream med...

  9. Pulser injection with subsequent removal for gamma-ray spectrometry

    DOE Patents [OSTI]

    Hartwell, Jack K. (Idaho Falls, ID); Goodwin, Scott G. (Idaho Falls, ID); Johnson, Larry O. (Blackfoot, ID); Killian, E. Wayne (Idahoe Falls, ID)

    1990-01-01

    An improved system for gamma-ray spectroscopy characterized by an interface module that controls the injection of electronic pulses as well as separation logic that enables storage of pulser events in a region of the spectrum of a multichannel analyzer distinct from the region reserved for storage of gamma-ray events. The module accomplishes this by tagging pulser events (high or low) injected into the amplification circuitry, adding an offset to the events so identified at the time the events are at the output of the analog to digital converter, and storing such events in the upper portion of the spectrum stored in the multichannel analyzer. The module can be adapted for use with existing gamma-ray spectroscopy equipment to provide for automatic analyses of radioisotopes.

  10. Gamma-Ray Bursts and Topology of the Universe

    E-Print Network [OSTI]

    Marek Biesiada

    1993-10-04

    In this letter we propose a physical explanation for recently reported correlations between pairs of close and antipodal gamma-ray bursts from publicly available BATSE catalogue. Our model is based on the cosmological scenario in which bursters are located at cosmological distances of order of 0.5--2~Gpc. Observed distribution of gamma-ray bursts strongly suports this assumption. If so gamma-ray bursts may provide a very good probe for investigating the topological structure of the Universe. We notice that correlation between antipodal events may in fact indicate that we live in the so called Ellis' small universe which has Friedman-Roberston-Walker metric structure and nontrivial topology.

  11. Fermi GBM Observations of Terrestrial Gamma-ray Flashes

    SciTech Connect (OSTI)

    Briggs, Michael S. [CSPAR, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States)

    2011-09-21

    Terrestrial Gamma-ray Flashes are short pulses of energetic radiation associated with thunderstorms and lightning. While the Gamma-ray Burst Monitor (GBM) on Fermi was designed to observe gamma-ray bursts, its large BGO detectors are excellent for observing TGFs. Using GBM, TGF pulses are seen to either be symmetrical or have faster rise time than fall times. Some TGFs are resolved into double, partially overlapping pulses. Using ground-based radio observations of lightning from the World Wide Lightning Location Network (WWLLN), TGFs and their associated lightning are found to be simultaneous to {approx_equal}40 {mu} s. The lightning locations are typically within 300 km of the sub-spacecraft point.

  12. SLAC All Access: Fermi Gamma-ray Space Telescope

    ScienceCinema (OSTI)

    Romani, Roger

    2014-06-24

    Three hundred and fifty miles overhead, the Fermi Gamma-ray Space Telescope silently glides through space. From this serene vantage point, the satellite's instruments watch the fiercest processes in the universe unfold. Pulsars spin up to 700 times a second, sweeping powerful beams of gamma-ray light through the cosmos. The hyperactive cores of distant galaxies spew bright jets of plasma. Far beyond, something mysterious explodes with unfathomable power, sending energy waves crashing through the universe. Stanford professor and KIPAC member Roger W. Romani talks about this orbiting telescope, the most advanced ever to view the sky in gamma rays, a form of light at the highest end of the energy spectrum that's created in the hottest regions of the universe.

  13. A grey gamma-ray transfer procedure for supernovae

    E-Print Network [OSTI]

    David J Jeffery

    1998-02-17

    The gamma-ray transfer in supernovae for the purposes of energy deposition in the ejecta can be approximated as grey radiative transfer using mean opacities. In past work there is a single pure absorption mean opacity which is a free parameter. Accurate results can be obtained by varying this mean opacity to fit the results of more accurate procedures. In this paper, we present a grey gamma-ray transfer procedure for energy deposition in which there are multiple mean opacities that are not free parameters and that have both absorption and scattering components. This procedure is based on a local-state (LS) approximation, and so we call it the LS grey gamma-ray transfer procedure or LS procedure for short.

  14. What Are Gamma-Ray Bursts -- The Unique Role of Very High Energy Gamma-Ray Observations

    E-Print Network [OSTI]

    Williams, D A; Baring, M G; Buckley, J; Connaughton, V; Coppi, P; Dermer, C; Digel, S; Dingus, B; Fryer, C; Gehrels, N; Granot, J; Horan, D; Katz, J I; Mészáros, P; Norris, J; Parkinson, P Saz; Peér, A; Razzaque, S; Sinnis, G; Wang, X Y; Weekes, T C; Zhang, B

    2009-01-01

    Gamma-ray bursts (GRBs) have been an enigma since their discovery forty years ago. However, considerable progress unraveling their mysteries has been made in recent years. Developments in observations, theory, and instrumentation have prepared the way so that the next decade can be the one in which we finally answer the question, "What are gamma-ray bursts?" This question encompasses not only what the progenitors are that produce the GRBs, but also how the enormous luminosity of the GRBs, concentrated in gamma rays, is achieved. Observations across the electromagnetic spectrum, from both the ground and space, will be required to fully tackle this important question. This white paper, mostly distilled from a recent study commissioned by the Division of Astrophysics of the American Physical Society, focuses on what very high energy (~100 GeV and above) gamma-ray observations can contribute. Very high energy gamma rays probe the most extreme high energy particle populations in the burst environment, testing mode...

  15. Gamma-ray shielding properties of some travertines in Turkey

    SciTech Connect (OSTI)

    Akkurt, Iskender; Guenoglu, Kadir

    2012-09-06

    The radiation is an essential phenomenon in daily life. There are various amounts of radioactivite substances in the underground and the earth was irradiated by this substances. Humans are exposed to various kind of radiation from these sources. The travertines are usually used as a coating material in buildings. In this study, the photon attenuation coefficients of some travertines have been measured using a gamma spectroscopy with NaI(Tl) detector. The measurements have been performed using {sup 60}Co source which gives 1173 and 1332 keV energies gamma rays and {sup 137}Cs source which gives 662 keV energy gamma rays and the results will be discussed.

  16. Large-Scale Anisotropy of EGRET Gamma Ray Sources

    E-Print Network [OSTI]

    Luis Anchordoqui; Thomas McCauley; Thomas Paul; Olaf Reimer; Diego F. Torres

    2005-06-24

    In the course of its operation, the EGRET experiment detected high-energy gamma ray sources at energies above 100 MeV over the whole sky. In this communication, we search for large-scale anisotropy patterns among the catalogued EGRET sources using an expansion in spherical harmonics, accounting for EGRET's highly non-uniform exposure. We find significant excess in the quadrupole and octopole moments. This is consistent with the hypothesis that, in addition to the galactic plane, a second mid-latitude (5^{\\circ} < |b| < 30^{\\circ}) population, perhaps associated with the Gould belt, contributes to the gamma ray flux above 100 MeV.

  17. High energy cosmic rays, gamma rays and neutrinos from AGN

    E-Print Network [OSTI]

    Yukio Tomozawa

    2008-02-03

    The author reviews a model for the emission of high energy cosmic rays, gamma-rays and neutrinos from AGN (Active Galactic Nuclei) that he has proposed since 1985. Further discussion of the knee energy phenomenon of the cosmic ray energy spectrum requires the existence of a heavy particle with mass in the knee energy range. A possible method of detecting such a particle in the Pierre Auger Project is suggested. Also presented is a relation between the spectra of neutrinos and gamma-rays emitted from AGN. This relation can be tested by high energy neutrino detectors such as ICECUBE, the Mediterranean Sea Detector and possibly by the Pierre Auger Project.

  18. Gamma-Ray Bursts as Sources of Strong Magnetic Fields

    E-Print Network [OSTI]

    Granot, Jonathan; Bromberg, Omer; Racusin, Judith L; Daigne, Frédéric

    2015-01-01

    Gamma-Ray Bursts (GRBs) are the strongest explosions in the Universe, which due to their extreme character likely involve some of the strongest magnetic fields in nature. This review discusses the possible roles of magnetic fields in GRBs, from their central engines, through the launching, acceleration and collimation of their ultra-relativistic jets, to the dissipation and particle acceleration that power their $\\gamma$-ray emission, and the powerful blast wave they drive into the surrounding medium that generates their long-lived afterglow emission. An emphasis is put on particular areas in which there have been interesting developments in recent years.

  19. Correlation between Gamma-Ray bursts and Gravitational Waves

    E-Print Network [OSTI]

    P. Tricarico; A. Ortolan; A. Solaroli; G. Vedovato; L. Baggio; M. Cerdonio; L. Taffarello; J. Zendri; R. Mezzena; G. A. Prodi; S. Vitale; P. Fortini; M. Bonaldi; P. Falferi

    2001-01-05

    The cosmological origin of $\\gamma$-ray bursts (GRBs) is now commonly accepted and, according to several models for the central engine, GRB sources should also emit at the same time gravitational waves bursts (GWBs). We have performed two correlation searches between the data of the resonant gravitational wave detector AURIGA and GRB arrival times collected in the BATSE 4B catalog. No correlation was found and an upper limit \\bbox{$h_{\\text{RMS}} \\leq 1.5 \\times 10^{-18}$} on the averaged amplitude of gravitational waves associated with $\\gamma$-ray bursts has been set for the first time.

  20. A Gamma-Ray Bursts' Fluence-Duration Correlation

    E-Print Network [OSTI]

    Istvan Horvath; Lajos G. Balazs; Peter Meszaros; Zsolt Bagoly; Attila Meszaros

    2005-08-01

    We present an analysis indicating that there is a correlation between the fluences and the durations of gamma-ray bursts, and provide arguments that this reflects a correlation between the total emitted energies and the intrinsic durations. For the short (long) bursts the total emitted energies are roughly proportional to the first (second) power of the intrinsic duration. This difference in the energy-duration relationship is statistically significant, and may provide an interesting constraint on models aiming to explain the short and long gamma-ray bursts.

  1. X-ray afterglows from gamma-ray bursts

    E-Print Network [OSTI]

    M. Tavani

    1997-03-24

    We consider possible interpretations of the recently detected X- ray afterglow from the gamma-ray burst source GRB 970228. Cosmological and Galactic models of gamma-ray bursts predict different flux and spectral evolution of X-ray afterglows. We show that models based on adiabatic expansion of relativistic forward shocks require very efficient particle energization or post-burst re-acceleration during the expansion. Cooling neutron star models predict a very distinctive spectral and flux evolution that can be tested in current X-ray data.

  2. NO CORRELATION BETWEEN HOST GALAXY METALLICITY AND GAMMA-RAY ENERGY RELEASE FOR LONG-DURATION GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Levesque, Emily M.; Kewley, Lisa J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Soderberg, Alicia M.; Berger, Edo, E-mail: emsque@ifa.hawaii.ed, E-mail: kewley@ifa.hawaii.ed, E-mail: asoderbe@cfa.harvard.ed, E-mail: eberger@cfa.harvard.ed [Smithsonian Astrophysical Observatory, 60 Garden St., MS-20, Cambridge, MA 02138 (United States)

    2010-12-10

    We compare the redshifts, host galaxy metallicities, and isotropic (E{sub {gamma}},iso) and beaming-corrected (E{sub {gamma}}) gamma-ray energy release of 16 long-duration gamma-ray bursts (LGRBs) at z < 1. From this comparison, we find no statistically significant correlation between host metallicity and redshift, E{sub {gamma}},iso, or E{sub {gamma}}. These results are at odds with previous theoretical and observational predictions of an inverse correlation between gamma-ray energy release and host metallicity, as well as the standard predictions of metallicity-driven wind effects in stellar evolutionary models. We consider the implications that these results have for LGRB progenitor scenarios, and discuss our current understanding of the role that metallicity plays in the production of LGRBs.

  3. A panchromatic view of relativistic jets in gamma-ray emitting narrow-line Seyfert 1 galaxies

    E-Print Network [OSTI]

    D'Ammando, F; Finke, J; Giroletti, M; Larsson, J

    2015-01-01

    Before the launch of the Fermi satellite only two classes of Active Galactic Nuclei (AGN) were known to generate relativistic jets and thus to emit up to the gamma-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first four years of observations by the Large Area Telescope (LAT) on board Fermi confirmed that these two populations represent the most numerous identified sources in the extragalactic gamma-ray sky, but the discovery of variable gamma-ray emission from 5 radio-loud Narrow-Line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible emerging third class of AGN with relativistic jets. Considering that NLSy1 are thought to be hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects, the knowledge of the development of relativistic jets, and the evolution of radio-loud AGN. In this context, the study of the radio-loud NLSy1 from radio to gamma-rays has received increasing attention. Here we discuss the radio-...

  4. HAWC: A Next Generation All-Sky VHE Gamma-Ray Telescope

    E-Print Network [OSTI]

    G. Sinnis; A. Smith; J. E. McEnery

    2004-03-03

    The study of the universe at energies above 100 GeV is a relatively new and exciting field. The current generation of pointed instruments have detected TeV gamma rays from at least 10 sources and the next generation of detectors promises a large increase in sensitivity. We have also seen the development of a new type of all-sky monitor in this energy regime based on water Cherenkov technology (Milagro). To fully understand the universe at these extreme energies requires a highly sensitive detector capable of continuously monitoring the entire overhead sky. Such an instrument could observe prompt emission from gamma-ray bursts and probe the limits of Lorentz invariance at high energies. With sufficient sensitivity it could detect short transients ($\\sim$15 minutes) from active galaxies and study the time structure of flares at energies unattainable to space-based instruments. Unlike pointed instruments a wide-field instrument can make an unbiased study of all active galaxies and enable many multi-wavelength campaigns to study these objects. This paper describes the design and performance of a next generation water Cherenkov detector. To attain a low energy threshold and have high sensitivity the detector should be located at high altitude ($>$ 4km) and have a large area ($\\sim$40,000 m$^2$). Such an instrument could detect gamma ray bursts out to a redshift of 1, observe flares from active galaxies as short as 15 minutes in duration, and survey the overhead sky at a level of 50 mCrab in one year.

  5. HAWC: a next generation all-sky VHE gamma-ray telescope

    SciTech Connect (OSTI)

    Sinnis, G. (Gus); Smith, A.; McEnery, J. E.

    2004-01-01

    The study of the universe at energies above 100 GeV is a relatively new and exciting field. The current generation of pointed instruments have detected TeV gamma rays from at least 10 sources and the next generation of detectors promises a large increase in sensitivity. We have also seen the development of a new type of all-sky monitor in this energy regime based on water Cherenkov technology (Milagro). To fully understand the universe at these extreme energies requires a highly sensitive detector capable of continuously monitoring the entire overhead sky. Such an instrument could observe prompt emission from gamma-ray bursts and probe the limits of Lorentz invariance at high energies. With sufficient sensitivity it could detect shorthransients ({approx}15 minutes) from active galaxies and study the time structure of flares at energies unattainable to space-based instruments. Unlike pointed instruments a wide-field instrument can make an unbiased study of all active galaxies and enable many multi-wavelength campaigns to study these objects. This paper describes the design and performance of a next generation water Cherenkov detector. To attain a low energy threshold and have high sensitivity the detector should be located at high altitude (> 4km) and have a large area ({approx}40,000 m{sup 2}). Such an instrument could detect gamma ray bursts out to a redshift of 1, observe flares from active galaxies as short as 15 minutes in duration, and survey the overhead sky at a level of 50 mCrab in one year.

  6. Gamma-ray Bursts and their Central Engines

    E-Print Network [OSTI]

    Stephan Rosswog

    2004-01-09

    Gamma-ray bursts are the most luminous and probably the most relativistic events in the universe. The last few years have seen a tremendous increase in our knowledge of these events, but the source of the bursts still remains elusive. I will summarise recent progress in this field with special emphasis on our understanding of the possible progenitor systems.

  7. Gamma-Ray Bursts from Neutron Star Mergers

    E-Print Network [OSTI]

    T. Piran

    1994-01-17

    Binary neutron stars merger (NS$^2$M) at cosmological distances is probably the only $\\gamma$-ray bursts model based on an independently observed phenomenon which is known to be taking place at a comparable rate. We describe this model, its predictions and some open questions.

  8. A Gamma-Ray Burst Bibliography, 1973-2001

    E-Print Network [OSTI]

    K. Hurley

    2002-01-18

    On the average, 1.5 new publications on cosmic gamma-ray bursts enter the literature every day. The total number now exceeds 5300. I describe here a relatively complete bibliography which is on the web, and which can be made available electronically in various formats.

  9. A Plasma Instability Theory of Gamma-Ray Burst Emission

    E-Print Network [OSTI]

    J. J. Brainerd

    1999-04-02

    A plasma instability theory is presented for the prompt radiation from gamma-ray bursts. In the theory, a highly relativistic shell interacts with the interstellar medium through the filamentation and the two-stream instabilities to convert bulk kinetic energy into electron thermal energy and magnetic field energy. The processes are not efficient enough to satisfy the Rankine-Hugoniot conditions, so a shock cannot form through this mechanism. Instead, the interstellar medium passes through the shell, with the electrons radiating during this passage. Gamma-rays are produced by synchrotron self-Compton emission. Prompt optical emission is also produced through this mechanism, while prompt radio emission is produced through synchrotron emission. The model timescales are consistent with the shortest burst timescales. To emit gamma-rays, the shell's bulk Lorentz factor must be greater than approximately 1000. For the radiative processes to be efficient, the interstellar medium density must satisfy a lower limit that is a function of the bulk Lorentz factor. Because the limits operate as selection effects, bursts that violate them constitute new classes. In particular, a class of optical and ultraviolet bursts with no gamma-ray emission should exist. The lower limit on the density of the interstellar medium is consistent with the requirements of the Compton attenuation theory, providing an explanation for why all burst spectra appear to be attenuated. Several tests of the theory are discussed, as are the next theoretical investigations that should be conducted.

  10. The Biggest Bangs The Mystery of Gamma-Ray Bursts,

    E-Print Network [OSTI]

    Katz, Jonathan I.

    . The Supernova Connection? 16. The Holy Grail 17. The End of the Beginning vii #12; #15; Afterword #15; Appendix viii #12; Chapter 16 The Holy Grail A few miles from Los Alamos, New Mexico, stands one of the most as it was happening, which had been the holy grail of gamma-ray burst astronomy for a quarter of a century. From

  11. Gamma-ray decay of levels in /sup 53/Cr

    SciTech Connect (OSTI)

    Dickens, J.K.; Larson, D.C.

    1987-11-01

    Gamma-ray decay of levels in the stable isotope /sup 53/Cr has been studied using /sup 53/Cr(n,n'..gamma..) reactions for incident neutron energies between threshold and 10 MeV. Of the 65 gamma rays or gamma-ray groups observed for neutron interactions with /sup 53/Cr, 50 have been placed or tentatively placed among 34 levels in /sup 53/Cr up to an excitation energy of 4.36 MeV. Deduced branching ratios are in reasonable agreement with previous measurements except for decay of the E/sub x/ = 1537-keV level. For the decay of the E/sub x/ = 1537-keV level we are unable to explain variations in the branching ratios of the transition gamma rays as a function of incident neutron energy within the framework of the presently known level structure of /sup 53/Cr and suggest the possibility of a second energy level at E/sub x/ = 1537 keV. 59 refs., 13 figs., 2 tabs.

  12. The HAWC Gamma-Ray Observatory: Design, Calibration, and Operation

    E-Print Network [OSTI]

    Abeysekara, A U; Alvarez, C; Álvarez, J D; Arceo, R; Arteaga-Velázquez, J C; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; Belmont, E; BenZvi, S Y; Berley, D; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Carramińana, A; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Díaz-Vélez, J C; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fernandez, A; Fiorino, D W; Fraija, N; Galindo, A; Garfias, F; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Hampel-Arias, Z; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-GarcIa, R; Marinelli, A; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Rivičre, C; Rosa-González, D; Salazar, H; Salesa, F; Sanchez, F E; Sandoval, A; Santos, E; Schneider, M; Silich, S; Sinnis, G; Smith, A J; Sparks, K; Springer, R W; Taboada, I; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Villaseńor, L; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2013-01-01

    The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is under construction 4100 meters above sea level at Sierra Negra, Mexico. We describe the design and cabling of the detector, the characterization of the photomultipliers, and the timing calibration system. We also outline a next-generation detector based on the water Cherenkov technique.

  13. Current Trends in Gamma Ray Detection for Radiological Emergency Response

    SciTech Connect (OSTI)

    Mukhopadhyay, S., Guss, P., Maurer, R.

    2011-08-18

    Passive and active detection of gamma rays from shielded radioactive materials, including special nuclear materials, is an important task for any radiological emergency response organization. This article reports on the current trends and status of gamma radiation detection objectives and measurement techniques as applied to nonproliferation and radiological emergencies.

  14. Constraints on relativity violations from gamma-ray bursts

    E-Print Network [OSTI]

    Alan Kostelecky; Matthew Mewes

    2013-01-23

    Tiny violations of the Lorentz symmetry of relativity and the associated discrete CPT symmetry could emerge in a consistent theory of quantum gravity such as string theory. Recent evidence for linear polarization in gamma-ray bursts improves existing sensitivities to Lorentz and CPT violation involving photons by factors ranging from ten to a million.

  15. Constraining axion by polarized prompt emission from gamma ray bursts

    E-Print Network [OSTI]

    A. Rubbia; A. S. Sakharov

    2007-08-21

    A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of invisible axion. The axionic induced dichroism of gamma rays at different energies should cause a misalignment of the polarization plane for higher energy events relative to that one for lower energies events resulting in the loss of statistics needed to form a pattern of the polarization signal to be recognized in a detector. According to this, any evidence of polarized gamma rays coming from an object with extended magnetic field could be interpreted as a constraint on the existence of the invisible axion for a certain parameter range. Based on reports of polarized MeV emission detected in several GRBs we derive a constraint on the axion-photon coupling. This constraint $\\g_{a\\gamma\\gamma}\\le 2.2\\cdot 10^{-11} {\\rm GeV^{-1}}$ calculated for the axion mass $m_a=10^{-3} {\\rm eV}$ is competitive with the sensitivity of CAST and becomes even stronger for lower masses.

  16. Technical evaluation of software for gamma-ray logging system

    SciTech Connect (OSTI)

    Stromswold, D.C.

    1994-05-01

    This report contains results of a technical review of software, identified as LGCALC, that processes data collected by a high-resolution gamma-ray borehole logging system. The software presently operates within Westinghouse Hanford Company, Department of Geosciences, to process data collected by the Radionuclide Logging System. The software has been reviewed for its suitability for processing data to be collected by new high-resolution gamma-ray logging trucks scheduled to begin operational tests within Westinghouse Tank Waste Remediation Systems during 1994. Examination of the program code and hands-on operational tests have shown that this software is suitable for its intended use of processing high-resolution gamma-ray data obtained from borehole logging. Most of the code requires no changes, but in a few limited cases, suggestions have been made to correct errors or improve operation. Section 4 describes these changes. The technical review has confirmed the appropriateness, correctness, completeness, and coding accuracy of algorithms used to process spectral gamma-ray data, leading to a calculation of subsurface radionuclide contaminants. Running the program with test data from calibration models has confirmed that the program operates correctly. Comparisons with hand calculations have shown the correctness of the output from the program, based on known input data. Section 3 describes these tests. The recommended action is to make the near term programming changes suggested in Section 4.1 and then use the LGCALC analysis program with the new high-resolution logging systems once they have been properly calibrated.

  17. Gamma Ray Bursts as Probes of the First Stars

    E-Print Network [OSTI]

    James E. Rhoads

    2001-11-01

    The redshift where the first stars formed is an important and unknown milestone in cosmological structure formation. The evidence linking gamma ray bursts (GRBs) with star formation activity implies that the first GRBs occurred shortly after the first stars formed. Gamma ray bursts and their afterglows may thus offer a unique probe of this epoch, because they are bright from gamma ray to radio wavelengths and should be observable to very high redshift. Indeed, our ongoing near-IR followup programs already have the potential to detect bursts at redshift z ~ 10. In these proceedings, we discuss two distinct ways of using GRBs to probe the earliest star formation. First, direct GRB counts may be used as a proxy for star formation rate measurements. Second, high energy cutoffs in the GeV spectra of gamma ray bursts due to pair production with high redshift optical and ultraviolet background photons contain information on early star formation history. The second method is observationally more demanding, but also more rewarding, because each observed pair creation cutoff in a high redshift GRB spectrum will tell us about the integrated star formation history prior to the GRB redshift.

  18. X-ray Spectral Properties of Gamma-Ray Bursts

    E-Print Network [OSTI]

    T. E. Strohmayer; E. E. Fenimore; T. Murakami; A. Yoshida

    1997-12-18

    We summarize the spectral characteristics of a sample of 22 bright gamma-ray bursts detected with the gamma-ray burst sensors aboard the satellite Ginga. This instrument employed a proportional and scintillation counter to provide sensitivity to photons in the 2 - 400 keV range, providing a unique opportunity to characterize the largely unexplored X-ray properties of gamma-ray bursts. The photon spectra of the Ginga bursts are well described by a low energy slope, a bend energy, and a high energy slope. In the energy range where they can be compared, this result is consistent with burst spectral analyses obtained from the BATSE experiment aboard the Compton Observatory. However, below 20 keV we find evidence for a positive spectral number index in approximately 40% of our burst sample, with some evidence for a strong rolloff at lower energies in a few events. There is a correlation (Pearson's r = -0.62) between the low energy slope and the bend energy. We find that the distribution of spectral bend energies extends below 10 keV. The observed ratio of energy emitted in the X-rays relative to the gamma-rays can be much larger than a few percent and, in fact, is sometimes larger than unity. The average for our sample is 24%.

  19. Neutralino Gamma-ray Signals from Accreting Halo Dark Matter

    E-Print Network [OSTI]

    Lars Bergstrom; Joakim Edsjo; Christofer Gunnarsson

    2000-12-15

    There is mounting evidence that a self-consistent model for particle cold dark matter has to take into consideration spatial inhomogeneities on sub-galactic scales seen, for instance, in high-resolution N-body simulations of structure formation. Also in more idealized, analytic models, there appear density enhancements in certain regions of the halo. We use the results from a recent N-body simulation of the Milky Way halo and investigate the gamma-ray flux which would be produced when a specific dark matter candidate, the neutralino, annihilates in regions of enhanced density. The clumpiness found on all scales in the simulation results in very strong gamma-ray signals which seem to already rule out some regions of the supersymmetric parameter space, and would be further probed by upcoming experiments, such as the GLAST gamma-ray satellite. As an orthogonal model of structure formation, we also consider Sikivie's simple infall model of dark matter which predicts that there should exist continuous regions of enhanced density, caustic rings, in the dark matter halo of the Milky Way. We find, however, that the gamma-ray signal from caustic rings is generally too small to be detectable.

  20. Spectral Gamma-ray Signatures of Cosmological Dark Matter Annihilation

    E-Print Network [OSTI]

    Lars Bergstrom; Joakim Edsjo; Piero Ullio

    2001-12-13

    We propose a new signature for weakly interacting massive particle (WIMP) dark matter, a spectral feature in the diffuse extragalactic gamma-ray radiation. This feature, a sudden drop of the gamma-ray intensity at an energy corresponding to the WIMP mass, comes from the asymmetric distortion of the line due to WIMP annihilation into two gamma-rays caused by the cosmological redshift. Unlike other proposed searches for a line signal, this method is not very sensitive to the exact dark matter density distribution in halos and subhalos. The only requirement is that the mass distribution of substructure on small scales follows approximately the Press-Schechter law, and that smaller halos are on the average denser than large halos, which is a generic outcome of N-body simulations of Cold Dark Matter, and which has observational support. The upcoming Gamma-ray Large Area Space Telescope (GLAST) will be eminently suited to search for these spectral features. For numerical examples, we use rates computed for supersymmetric particle dark matter, where a detectable signal is possible.

  1. Neutrino production in nucleonic interactions in gamma-ray bursters

    E-Print Network [OSTI]

    Hylke B. J. Koers

    2008-05-16

    Neutrinos produced in gamma-ray bursters (GRBers) may provide a unique probe for the physics of these extreme astrophysical systems. Here we discuss neutrino production in inelastic neutron-proton collisions within the relativistic outflows associated with GRBers. We consider both the widely used fireball model and a recently proposed magneto-hydrodynamic (MHD) model for the GRB outflow.

  2. Investigation of elemental analysis using neutron-capture gamma ray spectra

    E-Print Network [OSTI]

    Hamawi, John Nicholas

    1969-01-01

    This thesis evaluated the potential of neutron-capture gamma rays in elemental analysis. A large portion of the work was devoted to the development of a method for the analysis of weak peaks in gamma ray spectra. This was ...

  3. The Capabilities of the Alpha Magnetic Spectrometer as GeV Gamma-rays Detector

    E-Print Network [OSTI]

    R. Battiston

    1999-11-13

    The modeled performance of the Alpha Magnetic Spectrometer (AMS) as a high-energy (0.3 to 100 GeV) gamma-ray detector is described, and its gamma-ray astrophysics objectives are discussed.

  4. 1 Cactus Framework: Black Holes to Gamma Ray Bursts 7 Erik Schnetter1,2

    E-Print Network [OSTI]

    Contents 1 Cactus Framework: Black Holes to Gamma Ray Bursts 7 Erik Schnetter1,2 , Christian D. Ott 94720, USA 1.1 Current challenges in relativistic astrophysics and the Gamma- Ray Burst problem

  5. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE HETE-2 GAMMA-RAY BURST CATALOG

    E-Print Network [OSTI]

    Vanderspek, Roland K.

    Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the French Gamma-Ray Telescope experiment on board the High ...

  6. Prospects for Future Very High-Energy Gamma-Ray Sky Survey: Impact...

    Office of Scientific and Technical Information (OSTI)

    Prospects for Future Very High-Energy Gamma-Ray Sky Survey: Impact of Secondary Gamma Rays Citation Details In-Document Search Title: Prospects for Future Very High-Energy...

  7. Selected Results from Ground-Based Cosmic Ray and Gamma-Ray Experiments

    E-Print Network [OSTI]

    N. Magnussen

    1998-05-13

    Selected results from the HEGRA experiment on charged Cosmic Rays and on very high energy gamma-rays are presented. The MAGIC Telescope is presented as an outlook to the future of Gamma-Ray astronomy.

  8. Optical Observations of Gamma-Ray Bursts: Connections to GeV...

    Office of Scientific and Technical Information (OSTI)

    Optical Observations of Gamma-Ray Bursts: Connections to GeVTeV Jets Citation Details In-Document Search Title: Optical Observations of Gamma-Ray Bursts: Connections to GeVTeV...

  9. Pulse properties of terrestrial gamma-ray flashes detected by the Fermi Gamma-Ray Burst Monitor

    E-Print Network [OSTI]

    Foley, Suzanne; Briggs, Michael S; Connaughton, Valerie; Tierney, David; McBreen, Sheila; Dwyer, Joseph; Chaplin, Vandiver L; Bhat, P Narayana; Byrne, David; Cramer, Eric; Fishman, Gerald J; Xiong, Shaolin; Greiner, Jochen; Kippen, R Marc; Meegan, Charles A; Paciesas, William S; Preece, Robert D; von Kienlin, Andreas; Wilson-Hodge, Colleen

    2015-01-01

    The Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope has triggered on over 300 terrestrial gamma-ray flashes (TGFs) since its launch in June 2008. With 14 detectors, GBM collects on average ~100 counts per triggered TGF, enabling unprecedented studies of the time profiles of TGFs. Here we present the first rigorous analysis of the temporal properties of a large sample of TGFs (278), including the distributions of the rise and fall times of the individual pulses and their durations. A variety of time profiles are observed with 19 of TGFs having multiple pulses separated in time and 31 clear cases of partially overlapping pulses. The effect of instrumental dead time and pulse pileup on the temporal properties are also presented. As the observed gamma ray pulse structure is representative of the electron flux at the source, TGF pulse parameters are critical to distinguish between relativistic feedback discharge and lightning leader models. We show that at least 67% of TGFs at satellite ...

  10. arXiv:astro-ph/0509571v119Sep2005 Gamma-Ray Burst Early Afterglows

    E-Print Network [OSTI]

    Zhang, Bing

    arXiv:astro-ph/0509571v119Sep2005 Gamma-Ray Burst Early Afterglows Bing Zhang Department of Physics's Swift Gamma-Ray Burst Explorer open a new era for the multi-wavelength study of the very early afterglow phase of gamma-ray bursts (GRBs). GRB early afterglow information is essential to explore the unknown

  11. SOLAR SUBMILLIMETER AND GAMMA-RAY BURST EMISSION P. Kaufmann,1,2

    E-Print Network [OSTI]

    Giménez de Castro, Guillermo Carlos

    SOLAR SUBMILLIMETER AND GAMMA-RAY BURST EMISSION P. Kaufmann,1,2 J.-P. Raulin,1 A. M. Melo,1 E headings: gamma rays: bursts -- Sun: flares 1. INTRODUCTION The interaction of ultrarelativistic electrons observations of a burst in the submillimeter and gamma-ray ranges were obtained for the first time on 2001

  12. Title of dissertation: A SEARCH FOR BURSTS OF VERY HIGH ENERGY GAMMA RAYS

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    ABSTRACT Title of dissertation: A SEARCH FOR BURSTS OF VERY HIGH ENERGY GAMMA RAYS WITH MILAGRO though the search was optimized primarily for detecting the emission from Gamma-Ray Bursts (GRBs) or to any other kind of phenomena that produce bursts of VHE gamma rays. Measurements of the GRB spectra

  13. Climatic and biogeochemical effects of a galactic gamma ray burst Adrian L. Melott,1

    E-Print Network [OSTI]

    Jackman, Charles H.

    Climatic and biogeochemical effects of a galactic gamma ray burst Adrian L. Melott,1 Brian C. Jackman (2005), Climatic and biogeochemical effects of a galactic gamma ray burst, Geophys. Res. Lett., 32, L14808, doi:10.1029/2005GL023073. 1. Terrestrial Implications of Gamma Ray Bursts in Our Galaxy [2

  14. Characteristics of broadband lightning emissions associated with terrestrial gamma ray flashes

    E-Print Network [OSTI]

    Cummer, Steven A.

    . Introduction [2] Brief (typically bursts of gamma rays with mean energies of 2 MeV originating from the Earth's atmosphere, referred to as terrestrial gamma ray flashes (TGFs), have been observed by the Burst et al., 2010; Briggs et al., 2010]. With spectra typically harder than cosmic gamma ray bursts

  15. Constraining the Intergalactic Magnetic Field Through its Imprint on Gamma Ray Data from Distant Sources.

    E-Print Network [OSTI]

    Arlen, Timothy

    2013-01-01

    Energy Emission of Gamma-Ray Bursts. ” ApJ, 682:127–134,1 GeV = 10 9 eV GRB Gamma-ray burst HE High energy, 100 MeVrays”-either from gamma-ray bursts or flares from blazars

  16. Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    OG 2.3.07 Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope Gus for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts to gamma-ray bursts, the final stages of black hole evaporation) the most compelling reason may

  17. Gamma Ray Astronomy with Air Shower Arrays A.I. Mincer 1

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    and for searching for transient sources such as gamma ray bursts. The Milagro detector is currently operating such as gamma ray bursts or to study the time variation of ``steady'' sources, air shower arrays are usedGamma Ray Astronomy with Air Shower Arrays A.I. Mincer 1 New York University, New York, NY 10003

  18. UNIVERSITY OF CALIFORNIA Search for a TeV Component of GammaRay Bursts

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    UNIVERSITY OF CALIFORNIA IRVINE Search for a TeV Component of Gamma­Ray Bursts Using the Milagrito Acknowledgements xiii Curriculum Vitae xv Abstract xvi 1. Introduction 1 2. Gamma­Ray Bursts: Observations.2 The Compton Gamma­Ray Observatory . . . . . . . . . . . . . . . . . . . 6 2.3 BATSE's Contributions

  19. Milagro Search for Very High Energy Emission from Gamma-Ray Bursts in the Swift Era

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Milagro Search for Very High Energy Emission from Gamma-Ray Bursts in the Swift Era P. M. Saz an unprecedented number of rapid and accurate Gamma-Ray Burst (GRB) localizations, facilitating a flurry of follow as the flares. INTRODUCTION Some of the most important contributions to our understanding of gamma-ray bursts

  20. Studies of Gamma-Ray Burst Prompt Emission with RHESSI and NCT

    E-Print Network [OSTI]

    Bellm, Eric Christopher

    2011-01-01

    4 RHESSI Tests of Quasi-Thermal Gamma-Ray Burst Spectral 4.1List of Tables ix Acknowledgments 1 Gamma-Ray Bursts 1.1 GRBx 2 RHESSI Gamma-Ray Burst Analysis Methods 2.1 The RHESSI

  1. A ground level gamma-ray burst observed in association with rocket-triggered lightning

    E-Print Network [OSTI]

    Florida, University of

    A ground level gamma-ray burst observed in association with rocket-triggered lightning J. R. Dwyer 2004; published 13 March 2004. [1] We report the observation of an intense gamma-ray burst observed lightning channel with gamma-ray energies extending up to more than 10 MeV. The burst consisted of 227

  2. Did a gamma-ray burst initiate the late Ordovician mass extinction?

    E-Print Network [OSTI]

    Jackman, Charles H.

    Did a gamma-ray burst initiate the late Ordovician mass extinction? A.L. Melott1 , B.S. Lieberman2 Abstract: Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe words: Population and evolution, mass extinction, gamma-ray burst, Ordovician, ultraviolet ozone

  3. Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts

    E-Print Network [OSTI]

    California at Berkeley, University of

    Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts V with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and Virgo's first science run. The IPN localisation of short gamma ray bursts is limited to extended error

  4. Search for Very High Energy Emission from Gamma-Ray Bursts using Milagro

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Search for Very High Energy Emission from Gamma-Ray Bursts using Milagro P. M. Saz Parkinson 95064 Abstract. Gamma-Ray Bursts (GRBs) have been detected at GeV energies by EGRET and models predict for very high energy emission from a sample of 106 gamma-ray bursts (GRB) detected since the beginning

  5. Limits on Very High Energy Emission from Gamma-Ray Bursts with the Milagro

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Limits on Very High Energy Emission from Gamma-Ray Bursts with the Milagro Observatory Miguel F of Milagro allow it to detect very high energy (VHE) gamma-ray burst emission with much higher sensitivity gamma-ray burst satellites at keV to MeV energies. Even in the absence of a positive detection, VHE

  6. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BATSE CATALOGS OF UNTRIGGERED COSMIC GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    California at Berkeley, University of

    THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BATSE CATALOGS OF UNTRIGGERED COSMIC GAMMA-RAY BURSTS gamma-ray bursts (GRBs) observed as untriggered events by the Burst and Transient Source Experiment to detect BATSE un- triggered bursts. Subject headinggs: catalogs -- gamma rays: bursts Online material

  7. GAMMA-RAY BURSTS AND THE EARTH: EXPLORATION OF ATMOSPHERIC, BIOLOGICAL, CLIMATIC, AND BIOGEOCHEMICAL EFFECTS

    E-Print Network [OSTI]

    Jackman, Charles H.

    GAMMA-RAY BURSTS AND THE EARTH: EXPLORATION OF ATMOSPHERIC, BIOLOGICAL, CLIMATIC Received 2005 May 19; accepted 2005 August 2 ABSTRACT Gamma-ray bursts (GRBs) are likely to have made extinction may have been initiated by a GRB. Subject headinggs: astrobiology -- gamma rays: bursts Online

  8. The Interplanetary Network Supplement to the BATSE 5B Catalog of Cosmic Gamma-Ray Bursts

    E-Print Network [OSTI]

    California at Berkeley, University of

    The Interplanetary Network Supplement to the BATSE 5B Catalog of Cosmic Gamma-Ray Bursts K. Hurley Interplanetary Network (IPN) localization information for 343 gamma-ray bursts observed by the Burst Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts

  9. Source altitudes of terrestrial gamma-ray flashes produced by lightning leaders

    E-Print Network [OSTI]

    Pasko, Victor

    ; published 18 April 2012. [1] Terrestrial gamma-ray flashes (TGFs) are energetic photon bursts observed fromSource altitudes of terrestrial gamma-ray flashes produced by lightning leaders Wei Xu,1 Sebastien. Pasko (2012), Source altitudes of terres- trial gamma-ray flashes produced by lightning leaders, Geophys

  10. Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts

    E-Print Network [OSTI]

    Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts C and massive stars, and the theoretical predictions of the characteristics must have the long gamma-ray burst of that document deals with the long soft gamma ray bursts (here type 2 bursts) and their possible relationship

  11. Discovery of TeV Gamma-Ray Emission from the Cygnus Region of the Galaxy

    E-Print Network [OSTI]

    Abdo, A A; Berley, D; Blaufuss, E; Casanova, S; Chen, C; Coyne, D G; Delay, R S; Dingus, B L; Ellsworth, R W; Fleysher, L; Fleysher, R; González, M M; Goodman, J A; Hays, E; Hoffman, C M; Kolterman, B E; Kelley, L A; Lansdell, C P; Linnemann, J T; McEnery, J E; Mincer, A I; Moskalenko, I V; Némethy, P; Noyes, D; Ryan, J M; Samuelson, F W; Parkinson, P M S; Schneider, M; Shoup, A; Sinnis, G; Smith, A J; Strong, A W; Sullivan, G W; Vasileiou, V; Walker, G P; Williams, D A; Xu, X W; Yodh, G B

    2006-01-01

    The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at ~12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray prod...

  12. Timing Gamma-ray Pulsars with the Fermi Large Area Telescope: Timing Noise and Astrometry

    E-Print Network [OSTI]

    Kerr, Matthew; Johnston, Simon; Shannon, Ryan; Camilo, Fernando

    2015-01-01

    We have constructed timing solutions for 81 gamma-ray pulsars covering more than five years of Fermi data. The sample includes 37 radio-quiet or radio-faint pulsars which cannot be timed with other telescopes. These timing solutions and the corresponding pulse times of arrival are prerequisites for further study, e.g. phase-resolved spectroscopy or searches for mode switches. Many gamma-ray pulsars are strongly affected by timing noise, and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model. We present an analysis of timing noise over the population using a new metric for characterizing its strength and spectral shape, namely its time-domain correlation. The dependence of the strength on spin frequency and spin-down rate is in good agreement with previous studies. We find that noise process power spectra $S(f)$ for unrecycled pulsars are steep, with strong correlations over our entire data set and spectral indices $S(f)\\propto f^{-\\alpha...

  13. Operation Greenhouse. Scientific Director's report of atomic weapon tests at Eniwetok, 1951. Annex 1. 2, delayed gamma-ray measurements. Part 1. Gamma-ray spectrum measurements (abridged)

    SciTech Connect (OSTI)

    Gibson, H.F.; Miller, W.; Motz, J.W.; Smeltzer, J.C.; Wyckoff, H.O.

    1985-09-01

    The measurement of bomb efficiencies from the number of gamma rays requires fundamentally two separate experiments. The average number of gamma rays emitted from the fission fragments (delayed gamma rays) per fission must be determined. This experiment can be carried out in the laboratory, a second experiment, the absolute determination of the number of gamma rays from the bomb are also attempted. Because gamma rays are not directly observable but are measured only through their secondary effects, and because the probability of occurrence of the secondary effects depends upon the gamma ray energy, it is not usually possible to count directly the number of gamma rays in a heterochromatic spectrum. A spectral distribution must be first obtained from which the actual total number of gamma rays may be computed. This volume discusses the planning for the experiment and the spectral distribution of collimated gamma rays determined from the Greenhouse tests on two shots. A discussion of measurement of build-up factor which is needed to estimate the effect of collimation is also given.

  14. CONSTRAINING THE HIGH-ENERGY EMISSION FROM GAMMA-RAY BURSTS WITH FERMI

    SciTech Connect (OSTI)

    Ackermann, M. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M.; Bechtol, K.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Buehler, R.; Cameron, R. A.; Charles, E. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Bonamente, E.; Cecchi, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Bouvier, A. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Caliandro, G. A., E-mail: jchiang@slac.stanford.edu, E-mail: kocevski@slac.stanford.edu, E-mail: moretti@particle.kth.se, E-mail: connauv@uah.edu, E-mail: valerie@nasa.gov, E-mail: michael.briggs@nasa.gov [Institut de Ciencies de l'Espai (IEEE-CSIC), Campus UAB, E-08193 Barcelona (Spain); Collaboration: Fermi Large Area Telescope Team; Fermi Gamma-ray Burst Monitor Team; and others

    2012-08-01

    We examine 288 gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the field of view of Fermi's Large Area Telescope (LAT) during the first 2.5 years of observations, which showed no evidence for emission above 100 MeV. We report the photon flux upper limits in the 0.1-10 GeV range during the prompt emission phase as well as for fixed 30 s and 100 s integrations starting from the trigger time for each burst. We compare these limits with the fluxes that would be expected from extrapolations of spectral fits presented in the first GBM spectral catalog and infer that roughly half of the GBM-detected bursts either require spectral breaks between the GBM and LAT energy bands or have intrinsically steeper spectra above the peak of the {nu}F{sub {nu}} spectra (E{sub pk}). In order to distinguish between these two scenarios, we perform joint GBM and LAT spectral fits to the 30 brightest GBM-detected bursts and find that a majority of these bursts are indeed softer above E{sub pk} than would be inferred from fitting the GBM data alone. Approximately 20% of this spectroscopic subsample show statistically significant evidence for a cutoff in their high-energy spectra, which if assumed to be due to {gamma}{gamma} attenuation, places limits on the maximum Lorentz factor associated with the relativistic outflow producing this emission. All of these latter bursts have maximum Lorentz factor estimates that are well below the minimum Lorentz factors calculated for LAT-detected GRBs, revealing a wide distribution in the bulk Lorentz factor of GRB outflows and indicating that LAT-detected bursts may represent the high end of this distribution.

  15. Solar Gamma Rays Powered by Secluded Dark Matter

    E-Print Network [OSTI]

    Brian Batell; Maxim Pospelov; Adam Ritz; Yanwen Shang

    2009-10-08

    Secluded dark matter models, in which WIMPs annihilate first into metastable mediators, can present novel indirect detection signatures in the form of gamma rays and fluxes of charged particles arriving from directions correlated with the centers of large astrophysical bodies within the solar system, such as the Sun and larger planets. This naturally occurs if the mean free path of the mediator is in excess of the solar (or planetary) radius. We show that existing constraints from water Cerenkov detectors already provide a novel probe of the parameter space of these models, complementary to other sources, with significant scope for future improvement from high angular resolution gamma-ray telescopes such as Fermi-LAT. Fluxes of charged particles produced in mediator decays are also capable of contributing a significant solar system component to the spectrum of energetic electrons and positrons, a possibility which can be tested with the directional and timing information of PAMELA and Fermi.

  16. Radiation detection system for portable gamma-ray spectroscopy

    DOE Patents [OSTI]

    Rowland, Mark S. (Alamo, CA); Howard, Douglas E. (Livermore, CA); Wong, James L. (Dublin, CA); Jessup, James L. (Tracy, CA); Bianchini, Greg M. (Livermore, CA); Miller, Wayne O. (Livermore, CA)

    2006-06-20

    A portable gamma ray detection apparatus having a gamma ray detector encapsulated by a compact isolation structure having at least two volumetrically-nested enclosures where at least one is a thermal shield. The enclosures are suspension-mounted to each other to successively encapsulate the detector without structural penetrations through the thermal shields. A low power cooler is also provided capable of cooling the detector to cryogenic temperatures without consuming cryogens, due to the heat load reduction by the isolation structure and the reduction in the power requirements of the cooler. The apparatus also includes a lightweight portable power source for supplying power to the apparatus, including to the cooler and the processing means, and reducing the weight of the apparatus to enable handheld operation or toting on a user's person.

  17. Fiber fed x-ray/gamma ray imaging apparatus

    DOE Patents [OSTI]

    Hailey, Charles J. (San Francisco, CA); Ziock, Klaus-Peter (Livermore, CA)

    1992-01-01

    X-ray/gamma ray imaging apparatus is disclosed for detecting the position, energy, and intensity of x-ray/gamma ray radiation comprising scintillation means disposed in the path of such radiation and capable of generating photons in response to such radiation; first photodetection means optically bonded to the scintillation means and capable of generating an electrical signal indicative of the intensity, and energy of the radiation detected by the scintillation means; second photodetection means capable of generating an electrical signal indicative of the position of the radiation in the radiation pattern; and means for optically coupling the scintillation means to the second photodetection means. The photodetection means are electrically connected to control and storage means which may also be used to screen out noise by rejecting a signal from one photodetection means not synchronized to a signal from the other photodetection means; and also to screen out signals from scattered radiation.

  18. Neutron and Gamma Ray Pulse Shape Discrimination with Polyvinyltoluene

    SciTech Connect (OSTI)

    Lintereur, Azaree T.; Ely, James H.; Stave, Jean A.; McDonald, Benjamin S.

    2012-03-01

    The goal of this was research effort was to test the ability of two poly vinyltoluene research samples to produce recordable, distinguishable signals in response to gamma rays and neutrons. Pulse shape discrimination was performed to identify if the signal was generated by a gamma ray or a neutron. A standard figure of merit for pulse shape discrimination was used to quantify the gamma-neutron pulse separation. Measurements were made with gamma and neutron sources with and without shielding. The best figure of merit obtained was 1.77; this figure of merit was achieved with the first sample in response to an un-moderated 252Cf source shielded with 5.08 cm of lead.

  19. Isotopic response with small scintillator based gamma-ray spectrometers

    DOE Patents [OSTI]

    Madden, Norman W. (Sparks, NV); Goulding, Frederick S. (Lafayette, CA); Asztalos, Stephen J. (Oakland, CA)

    2012-01-24

    The intrinsic background of a gamma ray spectrometer is significantly reduced by surrounding the scintillator with a second scintillator. This second (external) scintillator surrounds the first scintillator and has an opening of approximately the same diameter as the smaller central scintillator in the forward direction. The second scintillator is selected to have a higher atomic number, and thus has a larger probability for a Compton scattering interaction than within the inner region. Scattering events that are essentially simultaneous in coincidence to the first and second scintillators, from an electronics perspective, are precluded electronically from the data stream. Thus, only gamma-rays that are wholly contained in the smaller central scintillator are used for analytic purposes.

  20. Gamma Ray Burst as Sources of Exotic Particles

    E-Print Network [OSTI]

    Morgan, Ian; De Pree, Erin; Tennyson, Kevin

    2015-01-01

    We consider the possible production of stable lightest first level KK particle (LKP) in baryonic gamma ray bursts (GRB) out flows. We numerically computed the energy-dependent cross-sections of Kaluza-Klein (KK) excitations for the Standard Model gauge bosons, photon and Z. Next, we determined the feasibility of producing these KK excitations in gamma-ray emitting regions of GRBs. We found that a GRB fireball that accelerates baryons to energies greater than 10^14 eV could produce KK excitations out to approximately 10^12 cm from the central engine, indicating that GRBs may be a significant source of the LKP. Finally, we explore the potential observational consequences of our results.

  1. Gamma-ray bursts, axion emission and string theory dilaton

    E-Print Network [OSTI]

    O. Bertolami

    1999-01-14

    The emission of axions from supernovae is an interesting possibility to account for the Gamma-Ray Bursts provided their energy can be effectively converted into electromagnetic energy elsewhere. The connection between supernova and gamma-ray bursts has been recently confirmed by the observed correlation between the burst of April 25, 1998 and the supernova SN1998bw. We argue that the axion convertion into photons can be more efficient if one considers the coupling between an intermediate scale axion and the string theory dilaton along with the inclusion of string loops. We also discuss the way dilaton dynamics may allow for a more effective energy exchange with electromagnetic radiation in the expansion process of fireballs.

  2. Color Superconductivity in Compact Stars and Gamma Ray Bursts

    E-Print Network [OSTI]

    A. Drago; A. Lavagno; G. Pagliara

    2003-04-08

    We study the effects of color superconductivity on the structure and formation of compact stars. We show that it is possible to satisfy most of recent observational boundaries on masses and radii if a diquark condensate forms in a hybrid or a quark star. Moreover, we find that a huge amount of energy, of the order of $10^{53}$ erg, can be released in the conversion from a (metastable) hadronic star into a (stable) hybrid or quark star, if the presence of a color superconducting phase is taken into account. Accordingly to the scenario proposed in Astrophys.J.586(2003)1250, the energy released in this conversion can power a Gamma Ray Burst. This mechanism can explain the recent observations indicating a delay, of the order of days or years, between a few Supernova explosions and the subsequent Gamma Ray Burst.

  3. Gamma-ray Output Spectra from 239 Pu Fission

    SciTech Connect (OSTI)

    Ullmann, John [Los Alamos National Laboratory; Schwengner, R.; Zuber, K.

    2015-01-01

    Gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. A dependence of the gamma-ray spectrum on the gamma-ray multplicity was also observed. Global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.

  4. Crystal diffraction lens telescope for focusing nuclear gamma rays

    SciTech Connect (OSTI)

    Smither, R.K.; Fernandez, P.B.; Graber, T. [Argonne National Lab., IL (United States). Advanced Photon Source; Ballmoos, P. von; Naya, J.; Albernhe, F.; Vedrenne, G. [Centre d`Etude Spatiale des Rayonnements, Toulouse (France); Faiz, M. [KFUPM, Dhahran (Saudi Arabia). Physics Dept.

    1996-08-01

    A crystal diffraction lens was constructed at Argonne National Laboratory for use as a telescope to focus nuclear gamma rays. It consisted of 600 single crystals of germanium arranged in 8 concentric rings. The mounted angle of each crystal was adjusted to intercept and diffract the incoming gamma rays with an accuracy of a few arc sec. The performance of the lens was tested in two ways. In one case, the gamma rays were focused on a single medium size germanium detector. In the second case, the gamma rays were focused on the central germanium detector of a 3 x 3 matrix of small germanium detectors. The efficiency, image concentration and image quality, and shape were measured. The tests performed with the 3 x 3 matrix detector system were particularly interesting. The wanted radiation was concentrated in the central detector. The 8 other detectors were used to detect the Compton scattered radiation, and their energy was summed with coincident events in the central detector. This resulted in a detector with the efficiency of a large detector (all 9 elements) and the background of a small detector (only the central element). The use of the 3 x 3 detector matrix makes it possible to tell if the source is off axis and, if so, to tell in which direction. The crystal lens acts very much like a simple convex lens for visible light. Thus if the source is off to the left then the image will focus off to the right illuminating the detector on the right side: telling one in which direction to point the telescope. Possible applications of this type of crystal lens to balloon and satellite experiments will be discussed.

  5. Short Gamma-Ray Bursts from Binary Neutron Star Mergers

    E-Print Network [OSTI]

    Roland Oechslin; Thomas Janka

    2006-04-27

    We present the results from new relativistic hydrodynamic simulations of binary neutron star mergers using realistic non-zero temperature equations of state. We vary several unknown parameters in the system such as the neutron star (NS) masses, their spins and the nuclear equation of state. The results are then investigated with special focus on the post-merger torus-remnant system. Observational implications on the Gamma-ray burst (GRB) energetics are discussed and compared with recent observations.

  6. The Supernovae Associated with Gamma-Ray Bursts

    E-Print Network [OSTI]

    Thomas Matheson

    2004-10-27

    Supernovae (SNe) were long suspected as possible progenitors of gamma-ray bursts (GRBs). The arguments relied on circumstantial evidence. Several recent GRBs, notably GRB 030329, have provided direct, spectroscopic evidence that SNe and GRBs are related. The SNe associated with GRBs are all of Type Ic, implying a compact progenitor, which has implications for GRB models. Other peculiar Type Ic SNe may help to expand understanding of the mechanisms involved.

  7. On the origin of Gamma Ray Burst radiation

    E-Print Network [OSTI]

    G. Ghisellini

    2001-01-17

    In the standard internal shock model, the observed X and gamma-ray radiation is assumed to be produced by synchrotron emission. I will show that there are serious problems with this interpretation, calling for other radiation mechanisms, such as quasi-thermal Comptonization and/or Compton drag processes, or both. These new ideas can have important consequences on the more general internal shock scenario, and can be tested by future observations.

  8. Capture Gamma-Ray Libraries for Nuclear Applications

    SciTech Connect (OSTI)

    Sleaford, B.W.; Firestone, Richard B.; Summers, N.; Escher, J.; Hurst, A.; Krticka, M.; Basunia, S.; Molnar, G.; Belgya, T.; Revay, Z.; Choi, H.D.

    2010-05-01

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. This can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research Project. EGAF has been used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90percent of all the decay energy an is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. We use CASINO, a version of DICEBOX that is modified for this purpose. This can be used to simulate the neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modelling of unknown assemblies.

  9. The HAWC Gamma-Ray Observatory: Observations of Cosmic Rays

    E-Print Network [OSTI]

    Abeysekara, A U; Alvarez, C; Álvarez, J D; Arceo, R; Arteaga-Velázquez, J C; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; Belmont, E; BenZvi, S Y; Berley, D; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Carramińana, A; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Díaz-Vélez, J C; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fernandez, A; Fiorino, D W; Fraija, N; Galindo, A; Garfias, F; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Hampel-Arias, Z; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-GarcIa, R; Marinelli, A; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Rivičre, C; Rosa-González, D; Salazar, H; Salesa, F; Sanchez, F E; Sandoval, A; Santos, E; Schneider, M; Silich, S; Sinnis, G; Smith, A J; Sparks, K; Springer, R W; Taboada, I; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Villaseńor, L; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2013-01-01

    We describe measurements of GeV and TeV cosmic rays with the High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC. The measurements include the observation of the shadow of the moon; the observation of small-scale and large-scale angular clustering of the TeV cosmic rays; the prospects for measurement of transient solar events with HAWC; and the observation of Forbush decreases with the HAWC engineering array and HAWC-30.

  10. Search for neutrinos from Gamma-Ray Bursts with ANTARES

    E-Print Network [OSTI]

    Eleonora Presani

    2011-04-20

    A method to search for neutrino induced showers from gamma-ray bursts in the ANTARES detector is presented. ANTARES consists of a three-dimensional array of photosensitive devices that measure Cherenkov light induced by charged particles produced by high energy neutrinos interacting in the detector vicinity. The shower channel is complementary to the more commonly used upgoing muon channel. The corresponding detection volume is smaller, but has the advantage of being sensitive to neutrinos of any flavour.

  11. Dark gamma-ray bursts: possible role of multiphoton processes

    E-Print Network [OSTI]

    Mark E. Perel'man

    2009-07-27

    The absence of optical afterglow at some gamma-ray bursts (so called dark bursts) requires analyses of physical features of this phenomenon. It is shown that such singularity can be connected with multiphoton processes of frequencies summation in the Rayleigh- Jeans part of spectra, their pumping into higher frequencies. It can be registered most probably on young objects with still thin plasma coating, without further thermalization, i.e. soon after a prompt beginning of the explosive activity.

  12. Gamma-Ray Burst Detection with INTEGRAL/SPI

    E-Print Network [OSTI]

    Andreas von Kienlin; Nikolas Arend; Giselher Lichti; Andrew Strong; Paul Connell

    2004-07-05

    The spectrometer SPI, one of the two main instruments of the INTEGRAL spacecraft, has strong capabilities in the field of Gamma-Ray Burst (GRB) detections. In its 16 deg field of view (FoV) SPI is able to trigger and to localize GRBs with an accuracy for strong bursts better than 1 deg. The expected GRB detection rate is about one per month.

  13. Spectral Properties of Black Holes in Gamma Rays

    E-Print Network [OSTI]

    Sandip K. Chakrabarti

    2005-01-14

    Black holes are the most compact objects in the universe. Therefore, matter accreting onto is likely to radiate photons of energy comparable to very high gravitational potential energy. We discuss the nature of the emitted radiation in X-rays and gamma-rays from black hole candidates. We present theoretical solutions which comprise both Keplerian and sub-Keplerian components and suggest that shocks in accretion and outflows

  14. Gamma-Ray Logging Workshop (February 1981) | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:FinancingPetroleum12,Executive Compensation References: FARWashers |Gamma-Ray Logging Workshop

  15. Gamma-ray lines from SN2014J

    E-Print Network [OSTI]

    Siegert, Thomas

    2015-01-01

    On 21 January 2014, SN2014J was discovered in M82 and found to be the closest type Ia supernova (SN Ia) in the last four decades. INTEGRAL observed SN2014J from the end of January until late June for a total exposure time of about 7 Ms. SNe Ia light curves are understood to be powered by the radioactive decay of iron peak elements of which $^{56}$Ni is dominantly synthesized during the thermonuclear disruption of a CO white dwarf (WD). The measurement of $\\gamma$-ray lines from the decay chain $^{56}$Ni$\\rightarrow$$^{56}$Co$\\rightarrow$$^{56}$Fe provides unique information about the explosion in supernovae. Canonical models assume $^{56}$Ni buried deeply in the supernova cloud, absorbing most of the early $\\gamma$-rays, and only the consecutive decay of $^{56}$Co should become directly observable through the overlaying material several weeks after the explosion when the supernova envelope dilutes as it expands. Surprisingly, with the spectrometer on INTEGRAL, SPI, we detected $^{56}$Ni $\\gamma$-ray lines at ...

  16. Gamma Ray Burst Optical Counterpart Search Experiment (GROCSE)

    SciTech Connect (OSTI)

    Park, H.S.; Ables, E.; Bionta, R.M. [and others

    1995-10-27

    GROCSE (Gamma-Ray Optical Counterpart Search Experiments) is a system of automated telescopes that search for simultaneous optical activity associated with gamma ray bursts in response to real-time burst notifications provided by the BATSE/BACODINE network. The first generation system, GROCSE 1, is sensitive down to Mv {approximately} 8.5 and requires an average of 12 seconds to obtain the first images of the gamma ray burst error box defined by the BACODINE trigger. The collaboration is now constructing a second generation system which has a 4 second slewing time and can reach Mv {approximately} 14 with a 5 second exposure. GROCSE 2 consists of 4 cameras on a single mount. Each camera views the night sky through a commercial Canon lens (f/1.8, focal length 200 mm) and utilizes a 2K x 2K Loral CCD. Light weight and low noise custom readout electronics were designed and fabricated for these CCDs. The total field of view of the 4 cameras is 17.6 x 17.6 {degree}. GROCSE II will be operated by the end of 1995. In this paper, the authors present an overview of the GROCSE system and the results of measurements with a GROCSE 2 prototype unit.

  17. Gamma-Ray Bursts Above 1 GeV

    E-Print Network [OSTI]

    Matthew G. Baring

    1997-11-21

    One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most extreme of these was the single 18 GeV photon from the GRB940217 source. Given EGRET's sensitivity and limited field of view, the detection rate implies that such high energy emission may be ubiquitous in bursts. Hence expectations that bursts emit out to at least TeV energies are quite realistic, and the associated target-of-opportunity activity of the TeV gamma-ray community is well-founded. This review summarizes the observations and a handful of theoretical models for generating GeV--TeV emission in bursts sources, outlining possible ways that future positive detections could discriminate between different scenarios. The power of observations in the GeV--TeV range to distinguish between spectral structure intrinsic to bursts and that due to the intervening medium between source and observer is also discussed.

  18. Are we observing Lorentz violation in gamma ray bursts?

    E-Print Network [OSTI]

    Theodore G. Pavlopoulos

    2005-08-12

    From recent observations of gamma-ray bursts (GRBs), it appears that spectral time lags between higher-energy gamma rays photons and lower-energy photons vary with energy difference and time (distance) traveled. These lags appear to be smaller for the most luminous (close) bursts but larger for the fainter (farther away) bursts. From this observation, it has been suggested that it might be possible to determine the distance (L) these bursts have traveled from these time lags alone, without performing any red-shift measurements. These observed spreads (dispersion) of high-energy electromagnetic pulses of different energies with time contradict the special theory of relativity (STR). However, extended theories (ET) of the STR have been developed that contain a dispersive term, predicting the above observations. An example of such an ET is presented, allowing us to derive a relationship between time lags of gamma rays of different energies and distance L traveled from their origin. In addition, this theory predicts the origin of X-ray flashes.

  19. Exploring Broadband GRB Behavior During gamma-ray Emission

    E-Print Network [OSTI]

    S. A. Yost; H. F. Swan; E. S. Rykoff; F. Aharonian; C. W. Akerlof; A. Alday; M. C. B. Ashley; S. Barthelmy; D. Burrows; D. L. Depoy; R. J. Dufour; J. D. Eastman; R. D. Forgey; N. Gehrels; E. Gö?ü?; T. Güver; J. P. Halpern; L. C. Hardin; D. Horns; U. K?z?lo?lu; H. A. Krimm; S. Lepine; E. P. Liang; J. L. Marshall; T. A. McKay; T. Mineo; N. Mirabal; M. Özel; A. Phillips; J. L. Prieto; R. M. Quimby; P. Romano; G. Rowell; W. Rujopakarn; B. E. Schaefer; J. M. Silverman; R. Siverd; M. Skinner; D. A. Smith; I. A. Smith; S. Tonnesen; E. Troja; W. T. Vestrand; J. C. Wheeler; J. Wren; F. Yuan; B. Zhang

    2006-11-14

    The robotic ROTSE-III telescope network detected prompt optical emission contemporaneous with the gamma-ray emission of Swift events GRB051109A and GRB051111. Both datasets have continuous coverage at high signal-to-noise levels from the prompt phase onwards, thus the early observations are readily compared to the Swift XRT and BAT high energy detections. In both cases, the optical afterglow is established, declining steadily during the prompt emission. For GRB051111, there is evidence of an excess optical component during the prompt emission. The component is consistent with the flux spectrally extrapolated from the gamma-rays, using the gamma-ray spectral index. A compilation of spectral information from previous prompt detections shows that such a component is unusual. The existence of two prompt optical components - one connected to the high-energy emission, the other to separate afterglow flux, as indicated in GRB051111 - is not compatible with a simple ``external-external'' shock model for the GRB and its afterglow.

  20. Exploring Broadband GRB Behavior During gamma-ray Emission

    E-Print Network [OSTI]

    Yost, S A; Rykoff, E S; Aharonian, F; Akerlof, C W; Alday, A; Ashley, M C B; Barthelmy, S; Burrows, D; Depoy, D L; Dufour, R J; Eastman, J D; Forgey, R D; Gehrels, N; G"uver, T; Halpern, J P; Hardin, L C; Horns, D; Krimm, H A; Lepine, S; Liang, E P; Marshall, J L; McKay, T A; Mineo, T; Mirabal, N; Phillips, A; Prieto, J L; Quimby, R M; Romano, P; Rowell, G; Rujopakarn, W; Schaefer, B E; Silverman, J M; Siverd, R; Skinner, M; Smith, D A; Smith, I A; Tonnesen, S; Troja, E; Vestrand, W T; Wheeler, J C; Wren, J; Yuan, F; Zhang, B

    2006-01-01

    The robotic ROTSE-III telescope network detected prompt optical emission contemporaneous with the gamma-ray emission of Swift events GRB051109A and GRB051111. Both datasets have continuous coverage at high signal-to-noise levels from the prompt phase onwards, thus the early observations are readily compared to the Swift XRT and BAT high energy detections. In both cases, the optical afterglow is established, declining steadily during the prompt emission. For GRB051111, there is evidence of an excess optical component during the prompt emission. The component is consistent with the flux spectrally extrapolated from the gamma-rays, using the gamma-ray spectral index. A compilation of spectral information from previous prompt detections shows that such a component is unusual. The existence of two prompt optical components - one connected to the high-energy emission, the other to separate afterglow flux, as indicated in GRB051111 - is not compatible with a simple ``external-external'' shock model for the GRB and i...

  1. The Gamma Ray Burst Rate at High Photon Energies

    E-Print Network [OSTI]

    Karl Mannheim; Dieter Hartmann; Burkhardt Funk

    1996-05-17

    Some gamma-ray burst (GRB) spectra exhibit high energy tails with the highest photon energy detected at 18 GeV. The spectral slope of the high-energy tails is sufficiently flat in nu F_nu to consider the possibility of their detection at still higher energies. We calculate how many bursts can reasonably be expected above a given energy threshold for a cosmological distribution of bursts satisfying the observed apparent brightness distribution. The crucial point is that the gamma-ray absorption by pair production in the intergalactic diffuse radiation field eliminates bursts from beyond the gamma-ray horizon tau ~ 1, thus drastically reducing the number of bursts at high energies. Our results are consistent with the non-detection of bursts by current experiments in the 100 GeV to 100 TeV energy range. For the earth-bound detector array MILAGRO, we predict a maximal GRB rate of ~ 10 events per year. The Whipple Observatory can detect, under favorable conditions, ~1 event per year. The event rate for the HEGRA array is ~ 0.01 per year. Detection of significantly higher rates of bursts would severely challenge cosmological burst scenarios.

  2. TWO POPULATIONS OF GAMMA-RAY BURST RADIO AFTERGLOWS

    SciTech Connect (OSTI)

    Hancock, P. J.; Gaensler, B. M.; Murphy, T., E-mail: Paul.Hancock@Sydney.edu.au [Also at Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), The University of Sydney, Sydney, NSW 2006, Australia. (Australia)

    2013-10-20

    The detection rate of gamma-ray burst (GRB) afterglows is ?30% at radio wavelengths, much lower than in the X-ray (?95%) or optical (?70%) bands. The cause of this low radio detection rate has previously been attributed to limited observing sensitivity. We use visibility stacking to test this idea, and conclude that the low detection rate is instead due to two intrinsically different populations of GRBs: radio-bright and radio-faint. We calculate that no more than 70% of GRB afterglows are truly radio-bright, leaving a significant population of GRBs that lack a radio afterglow. These radio-bright GRBs have higher gamma-ray fluence, isotropic energies, X-ray fluxes, and optical fluxes than the radio-faint GRBs, thus confirming the existence of two physically distinct populations. We suggest that the gamma-ray efficiency of the prompt emission is responsible for the difference between the two populations. We also discuss the implications for future radio and optical surveys.

  3. Thermal-neutron capture gamma-rays. Volume 1

    SciTech Connect (OSTI)

    Tuli, J.K. [National Nuclear Data Center, Upton, NY (United States)

    1997-05-01

    The energy and photon intensity of gamma rays as seen in thermal-neutron capture are presented in ascending order of gamma energy. All those gamma-rays with intensity of {ge} 2% of the strongest transition are included. The two strongest transitions seen for the target nuclide are indicated in each case. Where the target nuclide mass number is indicated as nat the natural target was used. The gamma energies given are in keV. The gamma intensities given are relative to 100 for the strongest transition. All data for A > 44 are taken from Evaluated Nuclear Structure Data File (4/97), a computer file of evaluated nuclear structure data maintained by the National Nuclear Data Center, Brookhaven National Laboratory, on behalf of the Nuclear Structure and Decay and Decay Data network, coordinated by the International Atomic Energy Agency, Vienna. These data are published in Nuclear Data Sheets, Academic Press, San Diego, CA. The data for A {le} 44 is taken from ``Prompt Gamma Rays from Thermal-Neutron Capture,`` M.A. Lone, R.A. Leavitt, D.A. Harrison, Atomic Data and Nuclear Data Tables 26, 511 (1981).

  4. Gamma rays from the Galactic Centre region: a review

    E-Print Network [OSTI]

    van Eldik, Christopher

    2015-01-01

    During the last decades, increasingly precise astronomical observations of the Galactic Centre (GC) region at radio, infrared, and X-ray wavelengths laid the foundations to a detailed understanding of the high energy astroparticle physics of this most remarkable location in the Galaxy. Recently, observations of this region in high energy (HE, 10 MeV - 100GeV) and very high energy (VHE, > 100 GeV) gamma rays added important insights to the emerging picture of the Galactic nucleus as a most violent and active region where acceleration of particles to very high energies -- possibly up to a PeV -- and their transport can be studied in great detail. Moreover, the inner Galaxy is believed to host large concentrations of dark matter (DM), and is therefore one of the prime targets for the indirect search for gamma rays from annihilating or decaying dark matter particles. In this article, the current understanding of the gamma-ray emission emanating from the GC is summarised and the results of recent DM searches in HE...

  5. Unveiling the population of orphan Gamma Ray Bursts

    E-Print Network [OSTI]

    Ghirlanda, G; Campana, S; Vergani, S D; Japelj, J; Bernardini, M G; Burlon, D; D'Avanzo, P; Melandri, A; Gomboc, A; Nappo, F; Paladini, R; Pescalli, A; Salafia, O S; Tagliaferri, G

    2015-01-01

    Gamma Ray Bursts are detectable in the gamma-ray band if their jets are oriented towards the observer. However, for each GRB with a typical theta_jet, there should be ~2/theta_jet^2 bursts whose emission cone is oriented elsewhere in space. These off-axis bursts can be eventually detected when, due to the deceleration of their relativistic jets, the beaming angle becomes comparable to the viewing angle. Orphan Afterglows (OA) should outnumber the current population of bursts detected in the gamma-ray band even if they have not been conclusively observed so far at any frequency. We compute the expected flux of the population of orphan afterglows in the mm, optical and X-ray bands through a population synthesis code of GRBs and the standard afterglow emission model. We estimate the detection rate of OA by on-going and forthcoming surveys. The average duration of OA as transients above a given limiting flux is derived and described with analytical expressions: in general OA should appear as daily transients in o...

  6. EVIDENCE FOR GAMMA-RAY JETS IN THE MILKY WAY

    SciTech Connect (OSTI)

    Su Meng; Finkbeiner, Douglas P.

    2012-07-01

    Although accretion onto supermassive black holes in other galaxies is seen to produce powerful jets in X-ray and radio, no convincing detection has ever been made of a kpc-scale jet in the Milky Way. The recently discovered pair of 10 kpc tall gamma-ray bubbles in our Galaxy may be signs of earlier jet activity from the central black hole. In this paper, we identify a gamma-ray cocoon feature in the southern bubble, a jet-like feature along the cocoon's axis of symmetry, and another directly opposite the Galactic center in the north. Both the cocoon and jet-like feature have a hard spectrum with spectral index {approx} - 2 from 1 to 100 GeV, with a cocoon total luminosity of (5.5 {+-} 0.45) Multiplication-Sign 10{sup 35} and luminosity of the jet-like feature of (1.8 {+-} 0.35) Multiplication-Sign 10{sup 35} erg s{sup -1} at 1-100 GeV. If confirmed, these jets are the first resolved gamma-ray jets ever seen.

  7. Self-consistent computation of gamma-ray spectra due to proton-proton interactions in black hole systems

    E-Print Network [OSTI]

    S. Bhattacharyya; N. Bhatt; R. Misra

    2006-06-07

    In the inner regions of an accretion disk around a black hole, relativistic protons can interact with ambient matter to produce electrons, positrons and $\\gamma$-rays. The resultant steady state electron and positron particle distributions are self-consistently computed taking into account Coulomb and Compton cooling, $e^-e^+$ pair production (due to $\\gamma-\\gamma$ annihilation) and pair annihilation. While earlier works used the diffusion approximation to obtain the particle distributions, here we solve a more general integro-differential equation that correctly takes into account the large change in particle energy that occur when the leptons Compton scatter off hard X-rays. Thus this formalism can also be applied to the hard state of black hole systems, where the dominant ambient photons are hard X-rays. The corresponding photon energy spectrum is calculated and compared with broadband data of black hole binaries in different spectral states. The results indicate that the $\\gamma$-ray spectra ($E > 0.8$ MeV) of both the soft and hard spectral states and the entire hard X-ray/$\\gamma$-ray spectrum of the ultra-soft state, could be due to $p-p$ interactions. These results are consistent with the hypothesis that there always exists in these systems a $\\gamma$-ray spectral component due to $p-p$ interactions which can contribute between 0.5 to 10% of the total bolometric luminosty. The model predicts that {\\it GLAST} would be able to detect black hole binaries and provide evidence for the presence of non-thermal protons which in turn would give insight into the energy dissipation process and jet formation in these systems.

  8. ON THE RECENTLY DISCOVERED CORRELATIONS BETWEEN GAMMA-RAY AND X-RAY PROPERTIES OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Dado, Shlomo; Dar, Arnon [Physics Department, Technion, Haifa 32000 (Israel)

    2013-09-20

    Recently, many correlations between the prompt {gamma}-ray emission properties and the X-ray afterglow properties of gamma-ray bursts (GRBs) have been inferred from a comprehensive analysis of the X-ray light curves of more than 650 GRBs measured with the Swift X-Ray Telescope (Swift/XRT) during the years 2004-2010. We show that these correlations are predicted by the cannonball (CB) model of GRBs. They result from the dependence of GRB observables on the bulk motion Lorentz factor and viewing angle of the jet of highly relativistic plasmoids (CBs) that produces the observed radiations by interaction with the medium through which it propagates. Moreover, despite their different physical origins, long GRBs (LGRBs) and short-hard bursts (SHBs) in the CB model share similar kinematic correlations, which can be combined into triple correlations satisfied by both LGRBs and SHBs.

  9. GRB 050117: SIMULTANEOUS GAMMA-RAY AND X-RAY OBSERVATIONS WITH THE SWIFT SATELLITE Joanne E. Hill,1, 2

    E-Print Network [OSTI]

    Zhang, Bing

    The Swift Gamma-Ray Burst Explorer performed its first autonomous, X-ray follow-up to a newly detected GRB from the XRT position. Subject headingg: gamma rays: bursts 1. INTRODUCTION The Swift Gamma-ray Burst Explorer (Gehrels et al. 2004) was launched on 2004 November 20 to study gamma-ray bursts (GRBs) over

  10. Spectral analysis and interpretation of the \\gamma-ray emission from the Starburst galaxy NGC 253

    E-Print Network [OSTI]

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; Becherini, Y; Becker, J; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataď, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Gast, H; Gérard, L; Giebels, B; Glicenstein, J F; Glück, B; Göring, D; Grondin, M -H; Häffner, S; Hague, J D; Hahn, J; Hampf, D; Harris, J; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzy?ski, K; Katz, U; Kaufmann, S; Khélifi, B; Klochkov, D; Klu?niak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Krayzel, F; Laffon, H; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Mohamed, M; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Ońa; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Skilton, J L; Sol, H; Spengler, G; Stawarz, ?; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S

    2012-01-01

    Very-high-energy (VHE; E >100 GeV) and high-energy (HE; 100 MeV law in energy with differential photon index \\Gamma=2.14 \\pm 0.18_stat \\pm 0.30_sys and differential flux normalisation at 1 TeV of F_0 = (9.6 \\pm 1.5_stat (+5.7,-2.9)_sys) x 10^{-14} TeV^{-1} cm^{-2} s^{-1}. A power-law fit to the differential HE \\gamma-ray spectrum reveals a photon index of \\Gamma=2.24 \\pm 0.14_stat \\pm 0.03_sys and an integral flux between 200 MeV and 200 GeV of F(0.2-200 GeV) = (4.9 \\pm 1.0_stat \\pm 0.3_sys) x 10^{-9} cm^{-2} s^{-1}. No evidence for a spectral break or turnover is found over the dynamic range of both the LAT instrument and the H.E.S.S. experiment: a combined fit of a power law to the HE and VHE \\gamma-ray data results in a ...

  11. Are Durations of Weak Gamma-Ray Bursts Reliable?

    E-Print Network [OSTI]

    Maarten Schmidt

    2005-08-16

    Simulations in the GUSBAD Catalog of gamma-ray bursts suggest that the apparent duration of a burst decreases as its amplitude is decreased. We see no evidence for this effect in the BATSE catalog. We show that for a burst at the detection limit, the typical signal-to-noise ratio at the edges of the T90 duration is around 1.5, suggesting that T90 must be quite uncertain. The situation for T50 is less unfavorable. Simulations using the exact procedure to derive the durations in the BATSE catalog would be useful in quantifying the effect.

  12. On the Power Spectrum Density of Gamma Ray Bursts

    E-Print Network [OSTI]

    Motoko Suzuki; Masahiro Morikawa; Izumi Joichi

    2001-04-13

    Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density. Reanalyzing the expanded data, we have found a) the power-law comes from the global profile of the burst and not from the self-similar shots nor rapid fluctuations in the luminosity profile. b) The power indices vary from burst to burst and the value -1.67 is given simply as the mean value of the distribution; there is no systematic correlation among GRBs to yield the power law.

  13. Reverse Shock Emission in Gamma-ray Bursts Revisited

    E-Print Network [OSTI]

    Gao, He

    2015-01-01

    A generic synchrotron external shock model is the widely preferred paradigm used to interpret the broad-band afterglow data of gamma-ray bursts (GRBs), including predicted observable signatures from a reverse shock which have been confirmed by observations. Investigations of the nature of the reverse shock emission can provide valuable insights into the intrinsic properties of the GRB ejecta. Here we briefly review the standard and the extended models of the reverse shock emission, discussing the connection between the theory and observations, including the implications of the latest observational advances.

  14. High Energy Neutrinos from Cosmological Gamma-Ray Burst Fireballs

    E-Print Network [OSTI]

    Eli Waxman; John Bahcall

    1997-01-30

    Observations suggest that $\\gamma$-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a relativistic fireball. We show that a large fraction, $\\ge 10%$, of the fireball energy is expected to be converted by photo-meson production to a burst of $\\sim10^{14} eV$ neutrinos. A km^2 neutrino detector would observe at least several tens of events per year correlated with GRBs, and test for neutrino properties (e.g. flavor oscillations, for which upward moving $\\tau$'s would be a unique signature, and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible.

  15. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Pal'shin, V. D.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Oleynik, P. P.; Ulanov, M. V. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Hurley, K. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Cline, T.; Trombka, J.; McClanahan, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Boynton, W.; Fellows, C.; Harshman, K., E-mail: val@mail.ioffe.ru [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); and others

    2013-08-15

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, {approx}18 yr{sup -1}, exceeds that of many individual experiments.

  16. Gamma ray burst distances and the timescape cosmology

    E-Print Network [OSTI]

    Peter R. Smale

    2011-08-22

    Gamma ray bursts can potentially be used as distance indicators, providing the possibility of extending the Hubble diagram to redshifts ~7. Here we follow the analysis of Schaefer (2007), with the aim of distinguishing the timescape cosmological model from the \\LambdaCDM model by means of the additional leverage provided by GRBs in the range 2 < z < 7. We find that the timescape model fits the GRB sample slightly better than the \\LambdaCDM model, but that the systematic uncertainties are still too little understood to distinguish the models.

  17. GeV Emission from Collisional Magnetized Gamma Ray Bursts

    E-Print Network [OSTI]

    P. Mészáros; M. J. Rees

    2011-04-26

    Magnetic fields may play a dominant role in gamma-ray bursts, and recent observations by the Fermi satellite indicate that GeV radiation, when detected, arrives delayed by seconds from the onset of the MeV component. Motivated by this, we discuss a magnetically dominated jet model where both magnetic dissipation and nuclear collisions are important. We show that, for parameters typical of the observed bursts, such a model involving a realistic jet structure can reproduce the general features of the MeV and a separate GeV radiation component, including the time delay between the two. The model also predicts a multi-GeV neutrino component.

  18. Can Sequentially Linked Gamma-Ray Bursts Nullify Randomness?

    E-Print Network [OSTI]

    Charles Fleischer

    2012-05-02

    In order to nullify the property of randomness perceived in the dispersion of gamma-ray bursts (GRB's) we introduce two new procedures. 1. Create a segmented group of sequentially linked GRB's and quantify the resultant angles. 2. Create segmented groups of sequentially linked GRB's in order to identify the location of GRB's that are positioned at equidistance, by using the selected GRB as the origin for a paired point circle, where the circumference of said circle intercepts the location of other GRB's in the same group.

  19. Gravitational radiation from long gamma-ray bursts

    E-Print Network [OSTI]

    Maurice H. P. M. van Putten

    2001-02-11

    Long gamma-ray bursts (GRBs) are probably powered by high-angular momentum black hole-torus systems in suspended accretion. The torus will radiate gravitational waves as non-axisymmetric instabilities develop. The luminosity in gravitational-wave emissions is expected to compare favorably with the observed isotropic equivalent luminosity in GRB-afterglow emissions. This predicts that long GRBs are potentially the most powerful LIGO/VIRGO burst-sources in the Universe. Their frequency-dynamics is characterized by a horizontal branch in the $\\dot{f}(f)-$diagram.

  20. High Efficiency of Gamma-Ray Bursts Revisited

    E-Print Network [OSTI]

    Y. C. Zou; Z. G. Dai

    2007-03-07

    Using the conservation of energy and momentum during collisions of any two shells, we consider the efficiency of gamma-ray bursts by assuming that the ejecta from the central engine are equally massive and have the same Lorentz factors. We calculate the efficiency and the final Lorentz factor of the merged whole shell for different initial diversities of Lorentz factors and for different microscopic radiative efficiency. As a result, a common high efficiency in the range of 0.1 to 0.9 is considerable, and a very high value near 100% is also reachable if the diversity of the Lorentz factors is large enough.

  1. Gamma-ray Bursts Produced by Mirror Stars

    E-Print Network [OSTI]

    S. Blinnikov

    1999-02-21

    I argue that cosmic Gamma-ray Bursts (GRB) may be produced by collapses or mergers of stars made of `mirror' matter. The mirror neutrinos (which are sterile for our matter) produced at these events can oscillate into ordinary neutrinos. The annihilations or decays of the latter create an electron-positron plasma and subsequent relativistic fireball with a very low baryon load needed for GRBs. The concept of mirror matter is able to explain several key problems of modern astrophysics: neutrino anomalies, the missing mass, MACHO microlensing events and GRBs. Thus this concept becomes very appealing and should be considered quite seriously and attentively.

  2. Gamma-Ray Bursts and Dark Matter - a joint origin?

    E-Print Network [OSTI]

    Daniel Enstrom

    1998-10-14

    A scenario is presented where large quark-gluon plasma (QGP) objects escaping the quark-hadron transition in the early Universe account for the baryonic dark matter as well as act as the sources for gamma-ray bursts. Two basic assumptions are made. Firstly, we assume that a QGP consisting of u,d and s quarks is the absolute ground state of QCD and secondly, that the quark-hadron transition in the early Universe was of first order. Both particle physics and astrophysics constraints are discussed, mainly from an observational point of view.

  3. Gamma-Ray Bursts from Primordial Quark Objects in Space

    E-Print Network [OSTI]

    B. Anoushirvani; D. Enström; S. Fredriksson; J. Hansson; P. Ökvist; A. Nicolaidis; S. Ekelin

    1997-11-28

    We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majority of bursts. Therefore, we speculate about an early, and very energetic, origin of bursts, and suggest that they come from phase transitions in massive objects of pure quark matter, left over from the Big Bang.

  4. Gamma-ray bursts and the sociology of science

    E-Print Network [OSTI]

    A. De Rujula

    2003-06-16

    I discuss what we have learned about Gamma-Ray Bursts (GRBs) by studying their `afterglows', and how these are interpreted in the generally-accepted `fireball' model of GRBs, as well as in the generally-unaccepted `cannonball' model of the same phenomena. The interpretation of GRBs is a good example around which to frame a discussion of the different approaches to science found in various fields, such as high-energy physics (HEP), high-energy astrophysics, or even the deciphering of ancient languages. I use this example to draw conclusions on `post-academic' science, and on the current status of European HEP.

  5. A 3rd Class of Gamma Ray Bursts?

    E-Print Network [OSTI]

    I. Horvath

    1998-05-17

    Two classes of Gamma Ray Bursts have been identified so far, characterized by T_90 durations shorter and longer than approximately 2 seconds. We show here that the BATSE 3B data allow a good fit with three Gaussian distributions in log T_90. The chi^2 statistic indicates a 40 % probability for two Gaussians, whereas the three-Gaussian fit probability is 98 %. Using another statistical method, it is argued that the probability that the third class is a random fluctuation is less than 0.02 %.

  6. Milagro: A TeV Gamma-Ray Monitor of the Northern Hemisphere Sky

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    transients, such as gamma-ray bursts, and all sky surveys are diĆcult. A new type of TeV -ray observatoryMilagro: A TeV Gamma-Ray Monitor of the Northern Hemisphere Sky B.L. Dingus 1 , R. Atkins 1 , W type of very high energy (> a few 100 GeV) gamma-ray observatory, Milagro, has been built with a large

  7. Discovery of a High-Energy Gamma-Ray-Emitting Persistent Microquasar

    E-Print Network [OSTI]

    J. M. Paredes; J. Marti; M. Ribo; M. Massi

    2001-02-13

    Microquasars are stellar x-ray binaries that behave as a scaled down version of extragalactic quasars. The star LS 5039 is a new microquasar system with apparent persistent ejection of relativistic plasma at a 3 kiloparsec distance from the sun. It may also be associated with a gamma-ray source discovered by the Energetic Gamma Ray Experiment Telescope (EGRET) on board the COMPTON-Gamma Ray Observatory satellite. Before the discovery of LS 5039, merely a handful of microquasars had been identified in the Galaxy, and none of them was detected in high-energy gamma-rays.

  8. Frequency-Domain Multiplexed Readout for Superconducting Gamma-Ray Detectors

    E-Print Network [OSTI]

    Dreyer, Jonathan G.

    2008-01-01

    sensor arrays with a superconducting quantum interferenceMultiplexed Readout for Superconducting Gamma-Ray Detectorsdetectors based on superconducting transition edge sensors (

  9. Are Short and Long Gamma Ray Bursts Really of Different Origin?

    E-Print Network [OSTI]

    Ernst Karl Kunst

    2000-12-06

    It is shown that short and long gamma ray bursts (GRBs) are of the same origin and, furthermore, correlated with their duration.

  10. Proceedings of ICRC 2001: 1 c Copernicus Gesellschaft 2001 Status of the Milagro Gamma Ray Observatory

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Gamma Ray Observatory, located at an altitude of 8,600 feet in the Jemez Mountains of New Mexico of the solar mag

  11. Swift Pointing and the Association Between Gamma-Ray Bursts and Gravitational-Wave Bursts

    E-Print Network [OSTI]

    Lee Samuel Finn; Badri Krishnan; Patrick J. Sutton

    2003-04-11

    The currently accepted model for gamma-ray burst phenomena involves the violent formation of a rapidly rotating solar mass black hole. Gravitational waves should be associated with the black-hole formation, and their detection would permit this model to be tested, the black hole progenitor (e.g., coalescing binary or collapsing stellar core) identified, and the origin of the gamma rays (within the expanding relativistic fireball or at the point of impact on the interstellar medium) located. Even upper limits on the gravitational-wave strength associated with gamma-ray bursts could constrain the gamma-ray burst model. To do any of these requires joint observations of gamma-ray burst events with gravitational and gamma-ray detectors. Here we examine how the quality of an upper limit on the gravitational-wave strength associated with gamma-ray burst observations depends on the relative orientation of the gamma-ray-burst and gravitational-wave detectors, and apply our results to the particular case of the Swift Burst-Alert Telescope (BAT) and the LIGO gravitational-wave detectors. A result of this investigation is a science-based ``figure of merit'' that can be used, together with other mission constraints, to optimize the pointing of the Swift telescope for the detection of gravitational waves associated with gamma-ray bursts.

  12. Optical Observations of Gamma-Ray Bursts: Connections to GeV...

    Office of Scientific and Technical Information (OSTI)

    Observations of Gamma-Ray Bursts: Connections to GeVTeV Jets Vestrand, W. Thomas Los Alamos National Laboratory Astronomy & Astrophysics(79) Astronomy and Astrophysics Astronomy...

  13. Neutrino Emission from Gamma-Ray Burst Fireballs, Revised

    E-Print Network [OSTI]

    Svenja Hümmer; Philipp Baerwald; Walter Winter

    2012-05-02

    We review the neutrino flux from gamma-ray bursts, which is estimated from gamma-ray observations and used for the interpretation of recent IceCube data, from a particle physics perspective. We numerically calculate the neutrino flux for the same astrophysical assumptions as the analytical fireball neutrino model, including the dominant pion and kaon production modes, flavor mixing, and magnetic field effects on the secondary muons, pions, and kaons. We demonstrate that taking into account the full energy dependencies of all spectra, the normalization of the expected neutrino flux reduces by about one order of magnitude and the spectrum shifts to higher energies, where we can pin down the exact origin of the discrepancies by the re-computation of the analytical models. We also reproduce the IceCube-40 analysis for exactly the same bursts and same assumptions and illustrate the impact of uncertainties. We conclude that the baryonic loading of the fireballs, which is an important control parameter for the emission of cosmic rays, can be constrained significantly with the full-scale experiment after about ten years.

  14. Uncovering the intrinsic variability of gamma-ray bursts

    SciTech Connect (OSTI)

    Golkhou, Vahid Z.; Butler, Nathaniel R., E-mail: vgolkhou@asu.edu, E-mail: natbutler@asu.edu [Cosmology Initiative, Arizona State University, Tempe, AZ 85287, USA. (United States)

    2014-05-20

    We develop a robust technique to determine the minimum variability timescale for gamma-ray burst (GRB) light curves, utilizing Haar wavelets. Our approach averages over the data for a given GRB, providing an aggregate measure of signal variation while also retaining sensitivity to narrow pulses within complicated time series. In contrast to previous studies using wavelets, which simply define the minimum timescale in reference to the measurement noise floor, our approach identifies the signature of temporally smooth features in the wavelet scaleogram and then additionally identifies a break in the scaleogram on longer timescales as a signature of a true, temporally unsmooth light curve feature or features. We apply our technique to the large sample of Swift GRB gamma-ray light curves and for the first time—due to the presence of a large number of GRBs with measured redshift—determine the distribution of minimum variability timescales in the source frame. We find a median minimum timescale for long-duration GRBs in the source frame of ?t {sub min} = 0.5 s, with the shortest timescale found being on the order of 10 ms. This short timescale suggests a compact central engine (3 × 10{sup 3} km). We discuss further implications for the GRB fireball model and present a tantalizing correlation between the minimum timescale and redshift, which may in part be due to cosmological time dilation.

  15. Gamma-ray fluxes in Oklo natural reactors

    E-Print Network [OSTI]

    Gould, C R; Sonzogni, A A; 10.1103/PhysRevC.86.054602

    2012-01-01

    Uncertainty in the operating temperatures of Oklo reactor zones impacts the precision of bounds derived for time variation of the fine structure constant $\\alpha$. Improved $^{176}$Lu/$^{175}$Lu thermometry has been discussed but its usefulness may be complicated by photo excitation of the isomeric state $^{176m}$Lu by $^{176}$Lu($\\gamma,\\gamma^\\prime $) fluorescence. We calculate prompt, delayed and equilibrium $\\gamma$-ray fluxes due to fission of $^{235}$U in pulsed mode operation of Oklo zone RZ10. We use Monte Carlo modeling to calculate the prompt flux. We use improved data libraries to estimate delayed and equilibrium spectra and fluxes. We find $\\gamma$-ray fluxes as a function of energy and derive values for the coefficients $\\lambda_{\\gamma,\\gamma^\\prime}$ that describe burn-up of $^{176}$Lu through the isomeric $^{176m}$Lu state. The contribution of the ($\\gamma,\\gamma^\\prime $) channel to the $^{176}$Lu/$^{175}$Lu isotopic ratio is negligible in comparison to the neutron burn-up channels. Lutetium...

  16. Gamma-ray fluxes in Oklo natural reactors

    E-Print Network [OSTI]

    C. R. Gould; E. I. Sharapov; A. A. Sonzogni

    2012-11-21

    Uncertainty in the operating temperatures of Oklo reactor zones impacts the precision of bounds derived for time variation of the fine structure constant $\\alpha$. Improved $^{176}$Lu/$^{175}$Lu thermometry has been discussed but its usefulness may be complicated by photo excitation of the isomeric state $^{176m}$Lu by $^{176}$Lu($\\gamma,\\gamma^\\prime $) fluorescence. We calculate prompt, delayed and equilibrium $\\gamma$-ray fluxes due to fission of $^{235}$U in pulsed mode operation of Oklo zone RZ10. We use Monte Carlo modeling to calculate the prompt flux. We use improved data libraries to estimate delayed and equilibrium spectra and fluxes. We find $\\gamma$-ray fluxes as a function of energy and derive values for the coefficients $\\lambda_{\\gamma,\\gamma^\\prime}$ that describe burn-up of $^{176}$Lu through the isomeric $^{176m}$Lu state. The contribution of the ($\\gamma,\\gamma^\\prime $) channel to the $^{176}$Lu/$^{175}$Lu isotopic ratio is negligible in comparison to the neutron burn-up channels. Lutetium thermometry is fully applicable to analyses of Oklo reactor data.

  17. Spectral Energy Distributions of Gamma-ray Blazars

    E-Print Network [OSTI]

    Laura Maraschi; Giovanni Fossati

    1996-12-09

    Average Spectral Energy Distributions (SED) for different subgroups of blazars are derived from available homogeneous (but small) data sets, including the gamma-ray band. Comparing Flat Spectrum Radio Quasars (FSRQ) with BL Lacs extracted from radio (RBL) or X-ray surveys (XBL) remarkable differences and similarities are apparent: i) in all cases the overall SED from radio to gamma-rays shows two peaks; ii) the first and second peak fall in different frequency ranges for different objects, with a tendency for the most luminous objects to peak at lower frequencies; iii) the ratio between the two peak frequencies seems to be constant, while the luminosity ratio between the high and low frequency component increases from XBL to RBL and FSRQ. The variability properties, (amplitude and frequency dependence) are similar in different objects if referred to their respective peak frequencies. Finally, comparing spectral snapshots obtained at different epochs, the intensities of the two components at frequencies close and above their respective peaks seem to be correlated. The relevance of these properties for theoretical models is briefly discussed.

  18. Stochastic Acceleration Model of Gamma-Ray Burst with Decaying Turbulence

    E-Print Network [OSTI]

    Asano, Katsuaki

    2015-01-01

    The spectral shape of the prompt emissions of gamma-ray bursts (GRBs) is typically expressed by the Band function: smooth joining of two power-law functions for high-energy and low-energy regions. To reveal the origin of the Band function, we revisit the stochastic acceleration model, in which electrons are accelerated via scattering with turbulent waves in the GRB outflow. The balance between the acceleration and synchrotron cooling yields a narrow energy-distribution similar to the Maxwellian distribution. The synchrotron spectrum becomes consistent with the observed hard photon index for the low-energy region. On the other hand, the narrow electron energy distribution contradicts the power-law spectrum for the high-energy region. We consider an evolution of the electron energy distribution to solve this problem. The turbulence and magnetic field induced by a certain hydrodynamical instability gradually decay. According to this evolution, the typical synchrotron photon energy also decreases with time. The t...

  19. Confronting the Galactic Center Gamma Ray Excess With a Light Scalar Dark Matter

    E-Print Network [OSTI]

    Dilip Kumar Ghosh; Subhadeep Mondal; Ipsita Saha

    2015-01-26

    The Fermi Large Area Telescope observed an excess in gamma ray emission spectrum coming from the center of the Milky Way galaxy. This data reveals that a light Dark Matter (DM) candidate of mass in the range 31-40 GeV, dominantly decaying into $b\\bar b$ final state, can explain the presence of the observed bump in photon energy. We try to interpret this observed phenomena by sneutrino DM annihilation into pair of fermions in the Supersymmetric Inverse Seesaw Model (SISM). This model can also account for tiny non-zero neutrino masses satisfying existing neutrino oscillation data. We show that a Higgs portal DM in this model is in perfect agreement with this new interpretation besides satisfying all other existing collider, cosmological and low energy experimental constraints.

  20. Search for gamma-rays from the unusually bright GRB 130427A with the HAWC Gamma-ray Observatory

    E-Print Network [OSTI]

    Abeysekara, A U; Alvarez, C; Arceo, R; Arteaga-Velázquez, J C; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; BenZvi, S Y; Rosales, M Bonilla; Braun, J; Caballero-Mora, K S; Carramińana, A; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fiorino, D W; Fraija, N; Galindo, A; González, M M; Goodman, J A; Gussert, M; Hampel-Arias, Z; Harding, J P; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linnemann, J T; Longo, M; Luna-García, R; Malone, K; Marinelli, A; Marinelli, S S; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; Torres, E Mendoza; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T O; Patricelli, B; Pelayo, R; Ponce, E; Pretz, J; Pérez-Pérez, E G; Rivičre, C; Rosa-González, D; Salazar, H; Greus, F Salesa; Sandoval, A; Schneider, M; Sinnis, G; Smith, A J; Woodle, K Sparks; Springer, R W; Taboada, I; Tollefson, K; Torres, I; Ukwatta, T N; Villaseńor, L; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H; Álvarez, J D

    2014-01-01

    The long gamma-ray burst (GRB) 130427A was the most powerful burst ever detected with a redshift $z\\lesssim0.5$, featuring the highest energy photon so far detected from a GRB and the longest lasting emission above 100 MeV. The HAWC Gamma-ray Observatory is a new extensive air shower detector currently under construction in central Mexico. It features two data acquisition (DAQ) systems - one designed to readout full air-shower events (main DAQ) and the other one counting the signals in each photomultiplier tube (scaler DAQ). The burst occurred at a zenith angle of $57^\\circ$, when HAWC was running 10% of the final detector and collecting data with the scaler DAQ only. Based on the observed light curve at MeV-GeV energies, 8 different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC de...

  1. Gamma Ray Burst Section of the White Paper on the Status and Future of Ground-based TeV Gamma-ray Astronomy

    E-Print Network [OSTI]

    Falcone, A D; Baring, M G; Blandford, R; Buckley, J; Connaughton, V; Coppi, P; Dermer, C; Dingus, B; Fryer, C; Gehrels, N; Granot, J; Horan, D; Katz, J I; Kühn, K; Mészáros, P; Norris, J; Parkinson, P Saz; Peér, A; Ramirez-Ruiz, E; Razzaque, S; Wang, X Y; Zhang, B

    2008-01-01

    This is a report on the findings of the gamma ray burst working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper is an APS commissioned document, and the overall version has also been released and can be found on astro-ph. This detailed section of the white paper discusses the status of past and current attempts to observe gamma ray bursts at GeV-TeV energies. We concentrate on the potential of future ground-based gamma-ray experiments to observe the highest energy emission ever recorded for GRBs, particularly for those that are nearby and have high Lorentz factors in the GRB jet. It is clear that major advances are possible and that the detection of very high energy emission would have strong implications for GRB models, as well as cosmic ray origin.

  2. Gamma Ray Burst Section of the White Paper on the Status and Future of Ground-based TeV Gamma-ray Astronomy

    E-Print Network [OSTI]

    A. D. Falcone; D. A. Williams; M. G. Baring; R. Blandford; J. Buckley; V. Connaughton; P. Coppi; C. Dermer; B. Dingus; C. Fryer; N. Gehrels; J. Granot; D. Horan; J. I. Katz; K. Kuehn; P. Meszaros; J. Norris; P. Saz Parkinson; A. Pe'er; E. Ramirez-Ruiz; S. Razzaque; X. Y. Wang; B. Zhang

    2008-10-02

    This is a report on the findings of the gamma ray burst working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper is an APS commissioned document, and the overall version has also been released and can be found on astro-ph. This detailed section of the white paper discusses the status of past and current attempts to observe gamma ray bursts at GeV-TeV energies. We concentrate on the potential of future ground-based gamma-ray experiments to observe the highest energy emission ever recorded for GRBs, particularly for those that are nearby and have high Lorentz factors in the GRB jet. It is clear that major advances are possible and that the detection of very high energy emission would have strong implications for GRB models, as well as cosmic ray origin.

  3. The Fermi Large Area gamma ray Telescope and the current searches for dark matter in space

    E-Print Network [OSTI]

    Morselli, Aldo

    but there are competing astrophysical sources, such as pulsars, that can give a strong flux of primary positrons Gamma-ray Space Telescope, has detected the largest amount of gamma rays, in the 20MeV 300GeV energy and electrons (see [10], [11], [12], [13] and references therein). At energies between 100 GeV and 1 Te

  4. Higgs-Portal Dark Matter for GeV Gamma-Ray Excess

    E-Print Network [OSTI]

    P. Ko; Wan-Il Park; Yong Tang

    2015-04-27

    We present Higgs-Portal dark matter (DM) models to explain the reported Galactic Center GeV gamma-ray excess. Naive effective theories are inconsistent with direct detection constraint for the relevant parameter range. Simple extended models with dark gauge symmetries can easily accommodate the gamma-ray excess through the Higgs-Portal coupling while satisfying various constraints.

  5. HETE, the High Energy Transient Explorer : unlocking the mysteries of gamma ray bursts

    E-Print Network [OSTI]

    Monnelly, Glen Pickslay, 1973-

    2002-01-01

    The High Energy Transient Explorer (HETE), was built primarily at MIT and launched in October 2000 with the goal of studying Gamma Ray Bursts (GRBs) at X-ray and gamma-ray energies. A suite of instruments aboard HETE provide ...

  6. UNIVERSITY of CALIFORNIA A SEARCH FOR TEV GAMMA-RAY BURST EMISSION WITH

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    UNIVERSITY of CALIFORNIA SANTA CRUZ A SEARCH FOR TEV GAMMA-RAY BURST EMISSION WITH THE MILAGRO . . . . . . . . . . . . . . . . . 5 1.4 GRB Host Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.5 Gamma-Ray Emission Processes . . . . . . . . . . . . . . . . . . . 10 1.6 Afterglows and Collimated Emission

  7. Short gamma-ray bursts from binary neutron star mergers in globular clusters

    E-Print Network [OSTI]

    Loss, Daniel

    ARTICLES Short gamma-ray bursts from binary neutron star mergers in globular clusters JONATHAN@cfa.harvard.edu Published online: 29 January 2006; doi:10.1038/nphys214 Observations by the Swift gamma-ray-burst (GRB, the so-called `long' GRBs (>2-200 s) were located by coded aperture imaging of their hard X-ray emission

  8. Neutrinos from gamma-ray bursts as a tool to explore quantum-gravity-induced

    E-Print Network [OSTI]

    Loss, Daniel

    LETTERS Neutrinos from gamma-ray bursts as a tool to explore quantum-gravity-induced Lorentz energy scale. According to existing models, gamma-ray bursts (GRBs) are accompanied by very high from the same direction as a GRB, months after the burst, would be statistically significant and imply

  9. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BeppoSAX GAMMA-RAY BURST CATALOGS

    E-Print Network [OSTI]

    Vanderspek, Roland K.

    Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 786 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments ...

  10. Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

    E-Print Network [OSTI]

    Moskalenko, Igor V.

    2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy releaseFermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C The Fermi LAT and Fermi GBM together record GRBs over a broad energy range spanning about 7 decades of gamma- ray energy. In September

  11. Neutron interrogation system using high gamma ray signature to detect contraband special nuclear materials in cargo

    DOE Patents [OSTI]

    Slaughter, Dennis R. (Oakland, CA); Pohl, Bertram A. (Berkeley, CA); Dougan, Arden D. (San Ramon, CA); Bernstein, Adam (Palo Alto, CA); Prussin, Stanley G. (Kensington, CA); Norman, Eric B. (Oakland, CA)

    2008-04-15

    A system for inspecting cargo for the presence of special nuclear material. The cargo is irradiated with neutrons. The neutrons produce fission products in the special nuclear material which generate gamma rays. The gamma rays are detecting indicating the presence of the special nuclear material.

  12. Effects of high-temperature anneals and 60 Co gamma-ray irradiation

    E-Print Network [OSTI]

    Schroder, Dieter K.

    Effects of high-temperature anneals and 60 Co gamma-ray irradiation on strained silicon on insulator was exposed to high-temperature annealing and high-dose 60 Co gamma -ray irradiation to study at a rate of approximately 5 105 °C/s for millisecond duration anneals. For the irradiation experiments

  13. 28th International Cosmic Ray Conference 2293 Search for Extremely High Energy Gamma Rays with the

    E-Print Network [OSTI]

    Hörandel, Jörg R.

    their directions of incidence points back to their points of production. The highest gamma ray energies identified28th International Cosmic Ray Conference 2293 Search for Extremely High Energy Gamma Rays, 76021 Karlsruhe, Germany (2) Institut f¨ur Kernphysik, Forschungszentrum Karlsruhe, 76021 Karlsruhe

  14. Are long gamma-ray bursts standard candles?

    E-Print Network [OSTI]

    Lin, Hai-Nan; Wang, Sai; Chang, Zhe

    2015-01-01

    Gamma-ray bursts (GRBs) are widely proposed as an effective probe to trace the Hubble diagram of the Universe in high redshift range. However, the calibration of GRBs is not as easy as that of type-Ia supernovae (SNe Ia). Most calibrating methods at present take use one or some of the empirical luminosity corrections, e.g., Amati relation. One of the underlying assumptions of these calibrating methods is that the empirical correlation is universal over all redshifts. In this paper, we check to what extent this assumption holds. Assuming that SNe Ia exactly trace the Hubble diagram of the Universe, we re-investigate the Amati relation for low redshift ($z1.4$) GRBs, respectively. It is found that the Amati relation of low-$z$ GRBs differs from that of high-$z$ GRBs at more than $3\\sigma$ confidence level. This result is insensitive to cosmological models.

  15. The Prompt and High Energy Emission of Gamma Ray Bursts

    SciTech Connect (OSTI)

    Meszaros, P.

    2009-05-25

    I discuss some recent developments concerning the prompt emission of gamma-ray bursts, in particular the jet properties and radiation mechanisms, as exemplified by the naked-eye burst GRB 080319b, and the prompt X-ray emission of XRB080109/SN2008d, where the progenitor has, for the first time, been shown to contribute to the prompt emission. I discuss then some recent theoretical calculations of the GeV/TeV spectrum of GRB in the context of both leptonic SSC models and hadronic models. The recent observations by the Fermi satellite of GRB 080916C are then reviewed, and their implications for such models are discussed, together with its interesting determination of a bulk Lorentz factor, and the highest lower limit on the quantum gravity energy scale so far.

  16. Gamma ray bursts and extreme energy cosmic rays

    SciTech Connect (OSTI)

    Scarsi, Livio

    1998-06-15

    Extreme Energy Cosmic Ray particles (EECR) with E>10{sup 20} eV arriving on Earth with very low flux ({approx}1 particle/Km{sup 2}-1000yr) require for their investigation very large detecting areas, exceeding values of 1000 km{sup 2} sr. Projects with these dimensions are now being proposed: Ground Arrays ('Auger' with 2x3500 km{sup 2} sr) or exploiting the Earth Atmosphere as seen from space ('AIR WATCH' and OWL,'' with effective area reaching 1 million km{sup 2} sr). In this last case, by using as a target the 10{sup 13} tons of air viewed, also the high energy neutrino flux can be investigated conveniently. Gamma Rays Bursts are suggested as a possible source for EECR and the associated High Energy neutrino flux.

  17. Gamma-Ray Bursts - a Primer For Relativists

    E-Print Network [OSTI]

    Tsvi Piran

    2002-05-12

    Gamma-Ray Bursts (GRBs) - short bursts of 100-1MeV photons arriving from random directions in the sky are probably the most relativistic objects discovered so far. Still, somehow they did not attract the attention of the relativistic community. In this short review I discuss briefly GRB observations and show that they lead us to the fireball model - GRBs involve macroscopic relativistic motion with Lorentz factors of a few hundred or more. I show that GRB sources involve, most likely, new born black holes, and their progenitors are Supernovae or neutron star mergers. I show that both GRB progenitors and the process of GRB itself produce gravitational radiation and I consider the possibility of detecting this emission. Finally I show that GRBs could serve as cosmological indicators that could teach us about the high redshift ($z \\approx 5-15$) dark ages of the universe.

  18. VAMOS: a Pathfinder for the HAWC Gamma-Ray Observatory

    E-Print Network [OSTI]

    Abeysekara, A U; Alvarez, C; Álvarez, J D; Ángeles, F; Arceo, R; Arteaga-Velázquez, J C; Avila-Aroche, A; Solares, H A Ayala; Badillo, C; Barber, A S; Baughman, B M; Bautista-Elivar, N; Gonzalez, J Becerra; Belmont, E; Benítez, E; BenZvi, S Y; Berley, D; Bernal, A; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Cabrera, I; Carramińana, A; Castańeda-Martínez, L; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Diaz-Azuara, A; Diaz-Cruz, L; Hernandez, R Diaz; Díaz-Vélez, J C; Dingus, B L; Dultzin, D; DuVernois, M A; Ellsworth, R W; Fernandez, A; Fiorino, D W; Fraija, N; Galindo, A; García-Torales, G; Garfias, F; González, A; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Guzmán-Cerón, C; Hampel-Arias, Z; Harding, J P; Hernández-Cervantes, L; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Langarica, R; Lara, A; Lara, G; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-Garcia, R; Marinelli, A; Martínez, L A; Martínez, H; Martínez, O; Martínez-Castro, J; Martos, M; Matthews, J A J; McEnery, J; Torres, E Mendoza; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Page, D P; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Ramírez, I; Renter, A; Rivičre, C; Rosa-González, D; Ruiz-Sala, F; Ruiz-Velasco, E L; Ryan, J; Sacahui, J R; Salazar, H; Salesa, F; Sandoval, A; Santos, E; Schneider, M; Silich, S; Sinnis, G; Smith, A J; Woodle, K Sparks; Springer, R W; Suarez, F; Taboada, I; Tepe, A; Toale, P A; Tollefson, K; Torres, I; Tinoco, S; Ukwatta, T N; Galicia, J F Valdés; Vanegas, P; Vázquez, A; Villaseńor, L; Wall, W; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2014-01-01

    VAMOS was a prototype detector built in 2011 at an altitude of 4100m a.s.l. in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design, construction techniques and data acquisition system of the HAWC observatory. HAWC is an air-shower array currently under construction at the same site of VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water Cherenkov detectors and two different data acquisition systems. It was in operation between October 2011 and May 2012 with an average live time of 30%. Besides the scientific verification purposes, the eight months of data were used to obtain the results presented in this paper: the detector response to the Forbush decrease of March 2012, and the analysis of possible emission, at energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.

  19. COSMOLOGICAL PARAMETERS FROM SUPERNOVAE ASSOCIATED WITH GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Li, Xue; Hjorth, Jens; Wojtak, Rados?aw, E-mail: lixue@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

    2014-11-20

    We report estimates of the cosmological parameters ? {sub m} and ?{sub ?} obtained using supernovae (SNe) associated with gamma-ray bursts (GRBs) at redshifts up to 0.606. Eight high-fidelity GRB-SNe with well-sampled light curves across the peak are used. We correct their peak magnitudes for a luminosity-decline rate relation to turn them into accurate standard candles with dispersion ? = 0.18 mag. We also estimate the peculiar velocity of the low-redshift host galaxy of SN 1998bw using constrained cosmological simulations. In a flat universe, the resulting Hubble diagram leads to best-fit cosmological parameters of (?{sub m},?{sub ?})=(0.58{sub ?0.25}{sup +0.22},0.42{sub ?0.22}{sup +0.25}). This exploratory study suggests that GRB-SNe can potentially be used as standardizable candles to high redshifts to measure distances in the universe and constrain cosmological parameters.

  20. Constraints On Holographic Cosmological Models From Gamma Ray Bursts

    E-Print Network [OSTI]

    Rivera, Alexander Bonilla

    2016-01-01

    We use Gamma Ray Bursts (GRBs) data to put additional constraints on a set of holographic dark energy models. GRBs are the most energetic events in the Universe and provide a complementary probe of dark energy by allowing the measurement of cosmic expansion history that extends to redshifts greater than 6 and they are complementary to SNIa test. We found that the LCDM model is the best fit to the data, although a preliminary statistical analysis seems to indicate that the holographic models studied show interesting agreement with observations, except Ricci Scale CPL model. These results show the importance of GRBs measurements to provide additional observational constraints to alternative cosmological models, which are necessary to clarify the way in the paradigm of dark energy or potential alternatives.

  1. Nucleosynthesis of heavy elements in gamma ray bursts

    E-Print Network [OSTI]

    ,

    2015-01-01

    The ultrarelativistic jets responsible for prompt and afterglow emission in gamma ray bursts are presumably driven by a central engine that consists of a dense accretion disk around a spinning black hole. We consider such engine, composed of free nucleons, electron-positron pairs, Helium nuclei, and cooled by neutrino emission. A significant number density of neutrons in the disk provide conditions for neutron rich plasma in the outflows and jets. Heavy nuclei are also formed in the accretion flow, at the distances 150-250 gravitational radii from the black hole. We study the process of nucleosynthesis in the GRB engine, depending on its physical properties. Our results may have important observational implications for the jet deceleration process and heavy elements observed in the spectra of GRB afterglows.

  2. Study of Lorentz violation in INTEGRAL Gamma-Ray Bursts

    E-Print Network [OSTI]

    Raphael Lamon; Nicolas Produit; Frank Steiner

    2007-09-27

    We search for possible time lags caused by quantum gravitational (QG) effects using gamma-ray bursts (GRBs) detected by INTEGRAL. The advantage of this satellite is that we have at our disposal the energy and arrival time of every detected single photon, which enhances the precision of the time resolution. We present a new method for seeking time lags in unbinned data using a maximum likelihood method and support our conclusions with Monte Carlo simulations. The analysis of the data yields a mass scale well below the Planck mass whose value may however increase if better statistics of GRBs were available. Furthermore, we disagree with previous studies in which a non-monotonic function of the redshift was used to perform a linear fit.

  3. General Relativistic Binary Merger Simulations and Short Gamma Ray Bursts

    E-Print Network [OSTI]

    Joshua A. Faber; Thomas W. Baumgarte; Stuart L. Shapiro; Keisuke Taniguchi

    2006-03-10

    The recent localization of some short-hard gamma ray bursts (GRBs) in galaxies with low star formation rates has lent support to the suggestion that these events result from compact object binary mergers. We discuss how new simulations in general relativity are helping to identify the central engine of short-hard GRBs. Motivated by our latest relativistic black hole-neutron star merger calculations, we discuss a scenario in which these events may trigger short-hard GRBs, and compare this model to competing relativistic models involving binary neutron star mergers and the delayed collapse of hypermassive neutron stars. Distinguishing features of these models may help guide future GRB and gravitational wave observations to identify the nature of the sources.

  4. Calorimetry of gamma-ray bursts: echos in gravitational waves

    E-Print Network [OSTI]

    Maurice H. P. M. van Putten; Amir Levinson

    2001-05-24

    Black holes surrounded by a disk or torus may drive the enigmatic cosmological gamma-ray bursts (GRBs). Equivalence in poloidal topology to pulsar magnetospheres shows a high incidence of the black hole-luminosity $L_H$ into the surrounding magnetized matter. We argue that this emission is re-radiated into gravitational waves at $L_{GW}\\simeq L_H/3$ in frequencies of order 1kHz, winds and, potentially, MeV neutrinos. The total energy budget and input to the GRB from baryon poor jets are expected to be standard in this scenario, consistent with recent analysis of afterglow data. Collimation of these outflows by baryon rich disk or torus winds may account for the observed spread in opening angles up to about $35^o$. This model may be tested by future LIGO/VIRGO observations.

  5. Polarized Gravitational Waves from Gamma-Ray Bursts

    E-Print Network [OSTI]

    Shiho Kobayashi; Peter Meszaros

    2003-01-24

    Significant gravitational wave emission is expected from gamma-ray bursts arising from compact stellar mergers, and possibly also from bursts associated with fast-rotating massive stellar core collapses. These models have in common a high angular rotation rate, and observations provide evidence for jet collimation of the photon emission, with properties depending on the polar angle, which may also be of relevance for X-ray flashes. Here we consider the gravitational wave emission and its polarization as a function of angle which is expected from such sources. We discuss possible correlations between the burst photon luminosity, or the delay between gravitational wave bursts and X-ray flashes, and the polarization degree of the gravitational waves.

  6. Waves on Noncommutative Spacetime and Gamma-Ray Bursts

    E-Print Network [OSTI]

    Giovanni Amelino-Camelia; Shahn Majid

    1999-07-14

    Quantum group Fourier transform methods are applied to the study of processes on noncommutative Minkowski spacetime $[x^i,t]=\\imath\\lambda x^i$. A natural wave equation is derived and the associated phenomena of {\\it in vacuo} dispersion are discussed. Assuming the deformation scale $\\lambda$ is of the order of the Planck length one finds that the dispersion effects are large enough to be tested in experimental investigations of astrophysical phenomena such as gamma-ray bursts. We also outline a new approach to the construction of field theories on the noncommutative spacetime, with the noncommutativity equivalent under Fourier transform to non-Abelianness of the `addition law' for momentum in Feynman diagrams. We argue that CPT violation effects of the type testable using the sensitive neutral-kaon system are to be expected in such a theory.

  7. Gravitational Wave Memory of Gamma-Ray Burst Jets

    E-Print Network [OSTI]

    Norichika Sago; Kunihito Ioka; Takashi Nakamura; Ryo Yamazaki

    2004-11-16

    Gamma-Ray Bursts (GRBs) are now considered as relativistic jets. We analyze the gravitational waves from the acceleration stage of the GRB jets. We show that (i) the point mass approximation is not appropriate if the opening half-angle of the jet is larger than the inverse of the Lorentz factor of the jet, (ii) the gravitational waveform has many step function like jumps, and (iii) the practical DECIGO and BBO may detect such an event if the GRBs occur in Local group of galaxy. We found that the light curve of GRBs and the gravitational waveform are anti-correlated so that the detection of the gravitational wave is indispensable to determine the structure of GRB jets.

  8. Gravitational Radiation from Gamma-Ray Burst Progenitors

    E-Print Network [OSTI]

    Shiho Kobayashi; Peter Meszaros

    2003-02-11

    We study gravitational radiation from various proposed gamma-ray burst (GRB) progenitor models, in particular compact mergers and massive stellar collapses. These models have in common a high angular rotation rate, and the final stage involves a rotating black hole and accretion disk system. We consider the in-spiral, merger and ringing phases, and for massive collapses we consider the possible effects of asymmetric collapse and break-up, as well bar-mode instabilities in the disks. We calculate the strain and frequency of the gravitational waves expected from various progenitors, at distances based on occurrence rate estimates. Based on simplifying assumptions, we give estimates of the probability of detection of gravitational waves by the advanced LIGO system from the different GRB scenarios.

  9. Properties of Low Luminosity Afterglow Gamma-ray Bursts

    E-Print Network [OSTI]

    Dereli, H; Gendre, B; Amati, L; Dichiara, S

    2015-01-01

    Aims: We characterize a sample of Gamma-Ray Bursts with low luminosity X-ray afterglows (LLA GRBs), and study their properties. Method: We select a sample consisting of the 12\\% faintest X-ray afterglows from the total population of long GRBs (lGRBs) with known redshift. We study their intrinsic properties (spectral index, decay index, distance, luminosity, isotropic radiated energy and peak energy) to assess whether they belong to the same population than the brighter afterglow events. Results: We present strong evidences that these events belong to a population of nearby events, different from that of the general population of lGRBs. These events are faint during their prompt phase, and include the few possible outliers of the Amati relation. Out of 14 GRB-SN associations, 9 are in LLA GRB sample, prompting for caution when using SN templates in observational and theoretical models for the general lGRBs population.

  10. Compact Gamma-ray Source Technology Development Study

    SciTech Connect (OSTI)

    Anderson, S G; Gibson, D J; Rusnak, B

    2009-09-25

    This study focuses on the applicability of current accelerator and laser technologies to the construction of compact, narrow bandwidth, gamma-ray sources for DHS missions in illicit materials detection. It also identifies research and development areas in which advancement will directly benefit these light sources. In particular, we review the physics of Compton scattering based light sources and emphasize the source properties most important to Nuclear Resonance Fluorescence (NRF) applications of interest. The influences of laser and electron beam properties on the light source are examined in order to evaluate the utility of different technologies for this application. Applicable bulk and fiber-based laser systems and laser recirculation technologies are discussed and Radio Frequency (RF) Linear Accelerator (linac) technologies are examined to determine the optimal frequency and pulse formats achievable.

  11. Physics of Gamma-Ray Bursts Prompt Emission

    E-Print Network [OSTI]

    Pe'er, Asaf

    2015-01-01

    In recent years, our understanding of gamma-ray bursts (GRB) prompt emission has been revolutionized, due to a combination of new instruments, new analysis methods and novel ideas. In this review, I describe the most recent observational results and the current theoretical interpretation. Observationally, a major development is the rise of time-resolved spectral analysis. These led to (I) identification of a distinguished high energy component, with GeV photons often seen at a delay; and (II) firm evidence for the existence of a photospheric (thermal) component in a large number of bursts. These results triggered many theoretical efforts aimed at understanding the physical conditions in the inner jet regions from which the prompt photons are emitted, as well as the spectral diversity observed. I highlight some areas of active theoretical research. These include: (I) understanding the role played by magnetic fields in shaping the dynamics of GRB outflow and spectra; (II) understanding the microphysics of kinet...

  12. Numerical Simulations of Gamma-Ray Burst Explosions

    E-Print Network [OSTI]

    Lazzati, Davide; López-Cámara, Diego

    2015-01-01

    Gamma-ray bursts are a complex, non-linear system that evolves very rapidly through stages of vastly different conditions. They evolve from scales of few hundred kilometers where they are very dense and hot to cold and tenuous on scales of parsecs. As such, our understanding of such a phenomenon can truly increase by combining theoretical and numerical studies adopting different numerical techniques to face different problems and deal with diverse conditions. In this review, we will describe the tremendous advancement in our comprehension of the bursts phenomenology through numerical modeling. Though we will discuss studies mainly based on jet dynamics across the progenitor star and the interstellar medium, we will also touch upon other problems such as the jet launching, its acceleration, and the radiation mechanisms. Finally, we will describe how combining numerical results with observations from Swift and other instruments resulted in true understanding of the bursts phenomenon and the challenges still lyi...

  13. The Earth's Gamma-ray Albedo as observed by EGRET

    SciTech Connect (OSTI)

    Petry, Dirk [Joint Center for Astrophysics, University of Maryland Baltimore County, Baltimore, MD 21250 (United States); NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2005-02-21

    The Earth's high energy gamma-ray emission is caused by cosmic ray interactions with the atmosphere. The EGRET detector on-board the CGRO satellite is only the second experiment (after SAS-2) to provide a suitable dataset for the comprehensive study of this emission. Approximately 60% of the EGRET dataset consist of gamma photons from the Earth. This conference contribution presents the first results from the first analysis project to tackle this large dataset. Ultimate purpose is to develop an analytical model of the Earth's emission for use in the GLAST project. The results obtained so far confirm the earlier results from SAS-2 and extend them in terms of statistical precision and angular resolution.

  14. GRAVITATIONAL WAVES OF JET PRECESSION IN GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Sun Mouyuan; Liu Tong; Gu Weimin; Lu Jufu, E-mail: tongliu@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)

    2012-06-10

    The physical nature of gamma-ray bursts (GRBs) is believed to involve an ultra-relativistic jet. The observed complex structure of light curves motivates the idea of jet precession. In this work, we study the gravitational waves of jet precession based on neutrino-dominated accretion disks around black holes, which may account for the central engine of GRBs. In our model, the jet and the inner part of the disk may precess along with the black hole, which is driven by the outer part of the disk. Gravitational waves are therefore expected to be significant from this black-hole-inner-disk precession system. By comparing our numerical results with the sensitivity of some detectors, we find that it is possible for DECIGO and BBO to detect such gravitational waves, particularly for GRBs in the Local Group.

  15. Radiative Transfer Models for Gamma-Ray Bursts

    E-Print Network [OSTI]

    Vurm, Indrek

    2015-01-01

    We present global radiative transfer models for heated relativistic jets. The simulations include all relevant radiative processes, starting deep in the opaque zone and following the evolution of radiation to and beyond the photosphere of the jet. The transfer models are compared with three gamma-ray bursts GRB 990123, GRB 090902B, and GRB 130427A, which have well-measured and different spectra. The models provide good fits to the observed spectra in all three cases. The fits give estimates for the jet magnetization parameter $\\varepsilon_{\\rm B}$ and the Lorentz factor $\\Gamma$. In the small sample of three bursts, $\\varepsilon_{\\rm B}$ varies between 0.01 and 0.1, and $\\Gamma$ varies between 340 and 1200.

  16. Open issues with the gamma-ray burst redshift distribution

    E-Print Network [OSTI]

    David Coward

    2007-02-27

    Cosmological gamma ray bursts (GRBs) are the brightest explosions in the Universe. Satellite detectors, such as Beppo-SAX, HETE2 and more recently Swift, have provided a wealth of data, including the localization and redshifts of subsets of GRBs. The redshift distribution has been utilized in several studies in attempts to constrain the evolving star formation rate and to probe GRB rate evolution in the high-redshift Universe. These studies find that the GRB luminosity function and/or the rate density evolve with redshift. We present a short review of the problems of constraining GRB rate evolution in the context of the complex mix of biases inherent in the redshift measurements. To disentangle GRB rate evolution from the biases prevalent in the redshift distribution will require accounting for the incompleteness of the observed redshift sample. We highlight the importance of formulating a `complete GRB selection function' to account for the main sources of bias.

  17. Short Gamma Ray Bursts as possible electromagnetic counterpart of coalescing binary systems

    E-Print Network [OSTI]

    S. Capozziello; M. De Laurentis; I. De Martino; M. Formisano

    2010-04-27

    Coalescing binary systems, consisting of two collapsed objects, are among the most promising sources of high frequency gravitational waves signals detectable, in principle, by ground-based interferometers. Binary systems of Neutron Star or Black Hole/Neutron Star mergers should also give rise to short Gamma Ray Bursts, a subclass of Gamma Ray Bursts. Short-hard-Gamma Ray Bursts might thus provide a powerful way to infer the merger rate of two-collapsed object binaries. Under the hypothesis that most short Gamma Ray Bursts originate from binaries of Neutron Star or Black Hole/Neutron Star mergers, we outline here the possibility to associate short Gamma Ray Bursts as electromagnetic counterpart of coalescing binary systems.

  18. Ion-induced gamma-ray detection of fast ions escaping from fusion plasmas

    SciTech Connect (OSTI)

    Nishiura, M., E-mail: nishiura@ppl.k.u-tokyo.ac.jp; Mushiake, T. [Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8561 (Japan); Doi, K.; Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyotanabe 610-0321 (Japan); Taniike, A.; Matsuki, T. [Graduate School of Maritime Sciences, Kobe University, Kobe 658-0022 (Japan); Shimazoe, K. [Graduate School of Engineering, The University of Tokyo, Tokyo 113-8654 (Japan); Yoshino, M. [Furukawa Co. Ltd., Tsukuba, Ibaraki 305-0856 (Japan); Nagasaka, T.; Tanaka, T.; Kisaki, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Fujimoto, Y.; Fujioka, K. [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan); Yamaoka, H. [RIKEN SPring-8 center, RIKEN, Sayo, Hyogo 679-5148 (Japan); Matsumoto, Y. [Tokushima Bunri University, Tokushima 770-8514 (Japan)

    2014-11-15

    A 12 × 12 pixel detector has been developed and used in a laboratory experiment for lost fast-ion diagnostics. With gamma rays in the MeV range originating from nuclear reactions {sup 9}Be(?, n?){sup 12}C, {sup 9}Be(d, n?){sup 12}C, and {sup 12}C(d, p?){sup 13}C, a high purity germanium (HPGe) detector measured a fine-energy-resolved spectrum of gamma rays. The HPGe detector enables the survey of background-gamma rays and Doppler-shifted photo peak shapes. In the experiments, the pixel detector produces a gamma-ray image reconstructed from the energy spectrum obtained from total photon counts of irradiation passing through the detector's lead collimator. From gamma-ray image, diagnostics are able to produce an analysis of the fast ion loss onto the first wall in principle.

  19. The agile alert system for gamma-ray transients

    SciTech Connect (OSTI)

    Bulgarelli, A.; Trifoglio, M.; Gianotti, F.; Fioretti, V.; Chen, A. W.; Pittori, C.; Verrecchia, F.; Lucarelli, F.; Santolamazza, P.; Fanari, G.; Giommi, P.; Pellizzoni, A.; and others

    2014-01-20

    In recent years, a new generation of space missions has offered great opportunities for discovery in high-energy astrophysics. In this article we focus on the scientific operations of the Gamma-Ray Imaging Detector (GRID) on board the AGILE space mission. AGILE-GRID, sensitive in the energy range of 30 MeV-30 GeV, has detected many ?-ray transients of both galactic and extragalactic origin. This work presents the AGILE innovative approach to fast ?-ray transient detection, which is a challenging task and a crucial part of the AGILE scientific program. The goals are to describe (1) the AGILE Gamma-Ray Alert System, (2) a new algorithm for blind search identification of transients within a short processing time, (3) the AGILE procedure for ?-ray transient alert management, and (4) the likelihood of ratio tests that are necessary to evaluate the post-trial statistical significance of the results. Special algorithms and an optimized sequence of tasks are necessary to reach our goal. Data are automatically analyzed at every orbital downlink by an alert pipeline operating on different timescales. As proper flux thresholds are exceeded, alerts are automatically generated and sent as SMS messages to cellular telephones, via e-mail, and via push notifications from an application for smartphones and tablets. These alerts are crosschecked with the results of two pipelines, and a manual analysis is performed. Being a small scientific-class mission, AGILE is characterized by optimization of both scientific analysis and ground-segment resources. The system is capable of generating alerts within two to three hours of a data downlink, an unprecedented reaction time in ?-ray astrophysics.

  20. GAMMA-RAY COMPTON LIGHT SOURCE DEVELOPMENT AT LLNL

    SciTech Connect (OSTI)

    Hartemann, F V; Anderson, S G; Gibson, D J; Hagmann, C A; Johnson, M S; Jovanovic, I; Messerly, M J; Pruet, J A; Shverdin, M Y; Tremaine, A M; McNabb, D P; Siders, C W; Barty, C J

    2007-08-15

    A new class of tunable, monochromatic {gamma}-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photoscience and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. A prototype, capable of producing > 10{sup 8} 0.7 MeV photons in a single shot, with a fractional bandwidth of 1%, and a repetition rate of 10 Hz, is currently under construction at LLNL; this system will be used to perform nuclear resonance fluorescence experiments. A new symmetrized S-band rf gun, using a Mg photocathode, will produce up to 1 nC of charge in an 8 ps bunch, with a normalized emittance modeled at 0.8 mm.mrad; electrons are subsequently accelerated up to 120 MeV to interact with a 500 mJ, 10 ps, 355 nm laser pulse and generate {gamma}-rays. The laser front end is a fiber-based system, using corrugated-fiber Bragg gratings for stretching, and drives both the frequency-quadrupled photocathode illumination laser and the Nd:YAG interaction laser. Two new technologies are used in the laser: a hyper-Michelson temporal pulse stacker capable of producing 8 ps square UV pulses, and a hyper-dispersion compressor for the interaction laser. Other key technologies, basic scaling laws, and recent experimental results will also be presented, along with an overview of future research and development directions.

  1. Constraints on the hadronic content of gamma ray bursts

    SciTech Connect (OSTI)

    Yacobi, Lee; Guetta, Dafne; Behar, Ehud [Department of Physics, Technion (Israel)

    2014-09-20

    The IceCube High-energy Neutrino Telescope has been collecting data since 2006. Conversely, hundreds of gamma-ray bursts (GRBs) have been detected by the GRB Monitor on board Fermi since its launch in 2008. So far no neutrino event has been associated with a GRB, despite many models predicting the generation of high-energy neutrinos through GRB photon interaction with PeV protons in the GRB jet. We use the non-detection of neutrinos to constrain the hadronic content of GRB jets independent of jet model parameters. Assuming a generic particle spectrum of E {sup –?} with ? = 2, we find that the ratio of the energy carried by pions to that in electrons has to be small f {sub ?}/f{sub e} ? 0.24 at 95% confidence level. A distribution of spectral slopes can lower f {sub ?}/f{sub e} by orders of magnitude. Another limit, independent of neutrinos, is obtained if one ascribes the measured Fermi/Large Area Telescope GeV gamma-ray emission to pair-photon cascades of high-energy photons resulting from (the same photon-hadronic interactions and subsequent) neutral pion decays. Based on the generally observed MeV-to-GeV GRB fluence ratio of ?10, we show that f {sub ?}/f{sub e} ? 0.3. In some bursts, this ratio is as low as unity, f {sub ?}/f{sub e} ? 0.03. These findings add to mounting doubts regarding the presence of PeV protons in GRB jets.

  2. Propagation of Neutrinos through Magnetized Gamma-Ray Burst Fireball

    E-Print Network [OSTI]

    Sarira Sahu; Nissim Fraija; Yong-Yeon Keum

    2009-11-10

    The neutrino self-energy is calculated in a weakly magnetized plasma consists of electrons, protons, neutrons and their anti-particles and using this we have calculated the neutrino effective potential up to order $M^{-4}_W$. In the absence of magnetic field it reduces to the known result. We have also calculated explicitly the effective potentials for different backgrounds which may be helpful in different environments. By considering the mixing of three active neutrinos in the medium with the magnetic field we have derived the survival and conversion probabilities of neutrinos from one flavor to another and also the resonance condition is derived. As an application of the above, we considered the dense and relativistic plasma of the Gamma-Ray Bursts fireball through which neutrinos of 5-30 MeV can propagate and depending on the fireball parameters they may oscillate resonantly or non-resonantly from one flavor to another. These MeV neutrinos are produced due to stellar collapse or merger events which trigger the Gamma-Ray Burst. The fireball itself also produces MeV neutrinos due to electron positron annihilation, inverse beta decay and nucleonic bremsstrahlung. Using the three neutrino mixing and considering the best fit values of the neutrino parameters, we found that electron neutrinos are hard to oscillate to another flavors. On the other hand, the muon neutrinos and the tau neutrinos oscillate with equal probability to one another, which depends on the neutrino energy, temperature and size of the fireball. Comparison of oscillation probabilities with and without magnetic field shows that, they depend on the neutrino energy and also on the size of the fireball. By using the resonance condition, we have also estimated the resonance length of the propagating neutrinos as well as the baryon content of the fireball.

  3. New Gamma-Ray Contributions to Supersymmetric Dark Matter Annihilation

    E-Print Network [OSTI]

    Torsten Bringmann; Lars Bergstrom; Joakim Edsjo

    2008-09-13

    We compute the electromagnetic radiative corrections to all leading annihilation processes which may occur in the Galactic dark matter halo, for dark matter in the framework of supersymmetric extensions of the Standard Model (MSSM and mSUGRA), and present the results of scans over the parameter space that is consistent with present observational bounds on the dark matter density of the Universe. Although these processes have previously been considered in some special cases by various authors, our new general analysis shows novel interesting results with large corrections that may be of importance, e.g., for searches at the soon to be launched GLAST gamma-ray space telescope. In particular, it is pointed out that regions of parameter space where there is a near degeneracy between the dark matter neutralino and the tau sleptons, radiative corrections may boost the gamma-ray yield by up to three or four orders of magnitude, even for neutralino masses considerably below the TeV scale, and will enhance the very characteristic signature of dark matter annihilations, namely a sharp step at the mass of the dark matter particle. Since this is a particularly interesting region for more constrained mSUGRA models of supersymmetry, we use an extensive scan over this parameter space to verify the significance of our findings. We also re-visit the direct annihilation of neutralinos into photons and point out that, for a considerable part of the parameter space, internal bremsstrahlung is more important for indirect dark matter searches than line signals.

  4. Gravitational Wave Memory from Gamma Ray Bursts' Jets

    E-Print Network [OSTI]

    Ofek Birnholtz; Tsvi Piran

    2013-06-18

    While the possible roles of GRBs' progenitors as Gravitational Waves (GW) sources have been extensively studied, little attention has been given to the jet itself as a GW source. We expect the jet's acceleration to produce a GW Memory signal. While all relativistic jet models display anti-beaming of GW radiation away from the jet axis, thus radiating away from directions of GRBs' gamma radiation, this effect is not overwhelming. The decrease of the signal amplitude towards the cone of gamma-ray detectability is weak, and for some models and parameters the GW signal reaches a significant amplitude for much of the gamma-ray cone. Thus both signals may be jointly detected. We find different waveforms and fourier signatures for uniform jets and structured jet models - thus offering a method of using GW signatures to probe the internal structure and acceleration of GRB jets. The GW signal peaks just outside the jet (core) of a uniform (structuted) jet. Within the jet (core) the GW signal displays wiggles, due to a polarization effect; thus for a uniform jet, the peak amplitude accompanies a smoother signal than the peak of a structured jet. For the most probable detection angle and for typical GRB parameters, we expect frequencies < ~600Hz and amplitudes h~10^-25. Our estimates of the expected signals suggest that the signals are not strong enough for a single cluster of DECIGO nor for aLIGO's sensitivities. However, sensitivies of ~10^-25/sqrt(Hz) in the DECIGO band should suffice to detect typical long GRBs at 2Gpc and short GRBs at 200Mpc, implying a monthly event of a long GRB and a detection of a short GRB every decade. In addition, we expect much more frequent detection of GW from GRBs directed away from us, including orphan afterglows. The ultimate DECIGO sensitivy should increase the range and enable detecting these signals in all models even to high cosmological z.

  5. Constraints on the Ultra-High Energy Neutrino Flux from Gamma-Ray Bursts from a Prototype Station of the Askaryan Radio Array

    E-Print Network [OSTI]

    Allison, P; Bard, R; Beatty, J J; Besson, D Z; Bora, C; Chen, C -C; Chen, P; Connolly, A; Davies, J P; DuVernois, M A; Fox, B; Gorham, P W; Hanson, K; Hill, B; Hoffman, K D; Hong, E; Hu, L -C; Ishihara, A; Karle, A; Kelley, J; Kravchenko, I; Landsman, H; Laundrie, A; Li, C -J; Liu, T; Lu, M -Y; Maunu, R; Mase, K; Meures, T; Miki, C; Nam, J; Nichol, R J; Nir, G; O'Murchadha, A; Pfendner, C G; Ratzlaff, K; Richman, M; Rotter, B; Sandstrom, P; Seckel, D; Shultz, A; Song, M; Stockham, J; Stockham, M; Sullivan, M; Touart, J; Tu, H -Y; Varner, G S; Yoshida, S; Young, R; Guetta, D

    2015-01-01

    We searched for ultra-high energy (UHE) neutrinos from Gamma-Ray Bursts (GRBs) with the Askaryan Radio Array (ARA) Testbed station's 2011-2012 data set. Among 589 GRBs monitored by the Gamma Ray Coordinate Network (GCN) catalog from Jan. 2011 to Dec. 2012 over the entire sky, 57 GRBs were selected for analysis. These GRBs were chosen because they occurred during a period of low anthropogenic background and high stability of the station and fell within our geometric acceptance. We searched for UHE neutrinos from 57 GRBs and observed 0 events, which is consistent with 0.11 expected background events. With this result, we set the limits on the UHE GRB neutrino fluence and quasi-diffuse flux from $10^{16}$ to $10^{19}$~eV. This is the first limit on the UHE GRB neutrino quasi-diffuse flux at energies above $10^{16}$~eV.

  6. Development of a gamma-ray detector with iridium transition edge sensor coupled to a Pb absorber

    E-Print Network [OSTI]

    Leman, Steven W.

    We have recently started to develop a high-resolution gamma-ray spectrometer for material defect analysis. Our gamma-ray detector is a microcalorimeter consisting of an iridium/gold bilayer transition edge sensor (TES) ...

  7. Space Detectors for Gamma Rays (100 MeV - 100 GeV): from EGRET to Fermi LAT

    E-Print Network [OSTI]

    Thompson, David J

    2015-01-01

    The design of spaceborne high-energy (E>100 MeV) gamma-ray detectors depends on two principal factors: (1) the basic physics of detecting and measuring the properties of the gamma rays; and (2) the constraints of operating such a detector in space for an extended period. Improvements in technology have enabled major advances in detector performance, as illustrated by two successful instruments, EGRET on the Compton Gamma Ray Observatory and LAT on the Fermi Gamma-ray Space Telescope.

  8. Title of Dissertation: A Search for Short Duration Very High Energy Emission from Gamma-Ray Bursts

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    of GRBs. #12;A Search for Short Duration Very High Energy Emission from Gamma-Ray Bursts by David NoyesABSTRACT Title of Dissertation: A Search for Short Duration Very High Energy Emission from Gamma-Ray by gamma rays with primary energies of approximately 100 GeV and higher. The wide field of view ( 2 sr

  9. JET BREAKS IN SHORT GAMMA-RAY BURSTS. II. THE COLLIMATED AFTERGLOW OF GRB 051221A David N. Burrows,1

    E-Print Network [OSTI]

    Zhang, Bing

    JET BREAKS IN SHORT GAMMA-RAY BURSTS. II. THE COLLIMATED AFTERGLOW OF GRB 051221A David N. Burrows gamma-ray burst (GRB) afterglow, using Chandra and Swift XRT observations of the X-ray afterglow of GRB: bursts Online material: color figures 1. INTRODUCTION Afterglows of short gamma-ray bursts (GRBs) have

  10. JET BREAKS IN SHORT GAMMA-RAY BURSTS. I. THE UNCOLLIMATED AFTERGLOW OF GRB 050724 Dirk Grupe,1

    E-Print Network [OSTI]

    Zhang, Bing

    JET BREAKS IN SHORT GAMMA-RAY BURSTS. I. THE UNCOLLIMATED AFTERGLOW OF GRB 050724 Dirk Grupe,1 the results of the Chandra observations of the Swift-discovered short gamma-ray burst GRB 050724. Chandra corrected energy of GRB 050724 is at least 4 ; 1049 ergs. Subject headinggs: gamma rays: bursts -- X-rays

  11. The gamma-ray burst monitor for Lobster-ISS L. Amati a,*, F. Frontera a,b

    E-Print Network [OSTI]

    Bogliolo, Alessandro

    The gamma-ray burst monitor for Lobster-ISS L. Amati a,*, F. Frontera a,b , N. Auricchio a , E telescope is flanked by a Gamma Ray Burst Monitor, with the minimum requirement of recognizing true GRBs. Published by Elsevier Ltd. All rights reserved. Keywords: Gamma-rays: bursts; X-rays: transients

  12. DELAYED GeVTeV PHOTONS FROM GAMMA-RAY BURSTS PRODUCING HIGH-ENERGY COSMIC RAYS

    E-Print Network [OSTI]

    Coppi, Paolo

    DELAYED GeV­TeV PHOTONS FROM GAMMA-RAY BURSTS PRODUCING HIGH-ENERGY COSMIC RAYS ELI WAXMAN A scenario in which cosmic rays (CRs) above 1020 eV are produced by cosmological gamma-ray bursts (GRBs provide information on the IGMF structure. Subject headings: cosmic rays -- gamma rays: bursts -- magnetic

  13. ON THE KINETIC ENERGY AND RADIATIVE EFFICIENCY OF GAMMA-RAY BURSTS Nicole M. Lloyd-Ronning1

    E-Print Network [OSTI]

    Zhang, Bing

    ON THE KINETIC ENERGY AND RADIATIVE EFFICIENCY OF GAMMA-RAY BURSTS Nicole M. Lloyd-Ronning1 of 17 gamma-ray bursts (GRBs) during the afterglow phase and ac- counting for radiative losses, we the implications of these results for the GRB radiation and jet models. Subject headinggs: gamma rays: bursts

  14. Terrestrial gamma ray flashes with energies up to 100 MeV produced by nonequilibrium acceleration of electrons

    E-Print Network [OSTI]

    Pasko, Victor

    . Introduction [2] Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating fromTerrestrial gamma ray flashes with energies up to 100 MeV produced by nonequilibrium accelerationV) of terrestrial gamma-ray flashes (TGFs). This analysis provides the first direct evidence that TGFs are produced

  15. Magnetic Fields in Gamma-Ray Bursts: A Short Racah Institute for Physics, The Hebrew University, Jerusalem, 91904 Israel

    E-Print Network [OSTI]

    Jensen, Grant J.

    Magnetic Fields in Gamma-Ray Bursts: A Short Overview Tsvi Piran Racah Institute for Physics Abstract. Magnetic fields play a crucial role in the physics of Gamma-Ray Bursts (GRBs). Strong thirty years, after the discovery of Gamma-Ray bursts (GRBs) we have now a reasonable GRB model

  16. Entire Complacency and Satisfaction 

    E-Print Network [OSTI]

    2009-12-24

    Character: Archivist12, Mina de Malfois - Character Additional Tags: Future Fic Collections: Yuletide Madness 2009 Stats: Published: 2009-12-24 Words: 811 Entire Complacency and Satisfaction by Carlanime Summary A quick look forward to the period immediately...

  17. Radioactive decay products in neutron star merger ejecta: heating efficiency and $\\gamma$-ray emission

    E-Print Network [OSTI]

    Hotokezaka, Kenta; Tanaka, Masaomi; Bamba, Aya; Terada, Yukikatsu; Piran, Tsvi

    2015-01-01

    The radioactive decay of the freshly synthesized $r$-process nuclei ejected in compact binary mergers power optical/infrared macronovae (kilonovae) that follow these events. The light curves depend critically on the energy partition among the different products of the radioactive decay and this plays an important role in estimates of the amount of ejected $r$-process elements from a given observed signal. We study the energy partition and $\\gamma$-ray emission of the radioactive decay. We show that $20$-$50\\%$ of the total radioactive energy is released in $\\gamma$-rays on timescales from hours to a month. The number of emitted $\\gamma$-rays per unit energy interval has roughly a flat spectrum between a few dozen keV and $1$ MeV so that most of this energy is carried by $\\sim 1$ MeV $\\gamma$-rays. However at the peak of macronova emission the optical depth of the $\\gamma$-rays is $\\sim 0.02$ and most of the $\\gamma$-rays escape. The loss of these $\\gamma$-rays reduces the heat deposition into the ejecta and h...

  18. Gamma Rays from Clusters and Groups of Galaxies: Cosmic Rays versus Dark Matter

    E-Print Network [OSTI]

    Tesla E. Jeltema; John Kehayias; Stefano Profumo

    2009-05-22

    Clusters of galaxies have not yet been detected at gamma-ray frequencies; however, the recently launched Fermi Gamma-ray Space Telescope, formerly known as GLAST, could provide the first detections in the near future. Clusters are expected to emit gamma rays as a result of (1) a population of high-energy primary and re-accelerated secondary cosmic rays (CR) fueled by structure formation and merger shocks, active galactic nuclei and supernovae, and (2) particle dark matter (DM) annihilation. In this paper, we ask the question of whether the Fermi telescope will be able to discriminate between the two emission processes. We present data-driven predictions for a large X-ray flux limited sample of galaxy clusters and groups. We point out that the gamma ray signals from CR and DM can be comparable. In particular, we find that poor clusters and groups are the systems predicted to have the highest DM to CR emission at gamma-ray energies. Based on detailed Fermi simulations, we study observational handles that might enable us to distinguish the two emission mechanisms, including the gamma-ray spectra, the spatial distribution of the signal and the associated multi-wavelength emissions. We also propose optimal hardness ratios, which will help to understand the nature of the gamma-ray emission. Our study indicates that gamma rays from DM annihilation with a high particle mass can be distinguished from a CR spectrum even for fairly faint sources. Discriminating a CR spectrum from a light DM particle will be instead much more difficult, and will require long observations and/or a bright source. While the gamma-ray emission from our simulated clusters is extended, determining the spatial distribution with Fermi will be a challenging task requiring an optimal control of the backgrounds.

  19. Towards the Final State of Spherical Gravitational Collapse and Likely Source of Gamma Ray Bursts

    E-Print Network [OSTI]

    Abhas Mitra

    1999-09-23

    We invoke the global properties of the actual GTR field equations for spherical collapse to directly show that the condition for formation of trapped surfaces, 2GM/R >1 is not allowed by GTR. And therefore all singularity theorems based on the assumption of formation of trapped surfaces are invalidated! Our conclusion is in perfect agreement with Einstein's intuitive idea that a Sch. like surface can not occur in reality. Further as singularity is approached R ->0, in order that 2GM/R 0! Harrison, et al. had also pointed out that collapse should come to a decisive end with M=0. This is possible in GTR if the fluid radiates its entire original mass-energy during the relentless graviatational contraction process, Q->M c^2! Since the actual efficiency for gamma ray production by the relevant blast wave may hardly exceed 10-20% and there could be a stronger (undetected) nu-anti-nu burst precding GRBs, the actual energy released for GRB 990123, even accounting for probable weak beaming, or for GRB 971214 (unbeamed) could be ~10^{54-55} erg. And such energy release may not be properly accountable without realizing that trapped surfaces are indeed not formed. All authors concerned with this subject, and particularly those, who would like to differ with our derivation are requested to send their criticism either directly or express the same openly for a healthy scientific discussion.

  20. CORRELATED SPECTRAL AND TEMPORAL BEHAVIOR OF LATE-TIME AFTERGLOWS OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Dado, Shlomo; Dar, Arnon [Physics Department, Technion, Haifa 32000 (Israel)

    2012-12-20

    The cannonball (CB) model of gamma-ray bursts (GRBs) predicts that the asymptotic behavior of the spectral energy density of GRB afterglows is a power law in time and in frequency, and the difference between the temporal and spectral power-law indices, {alpha}{sub X} - {beta}{sub X}, is restricted to the values 0, 1/2, and 1. Here we report the distributions of the values {alpha}{sub X} and {beta}{sub X}, and their difference for a sample of 315 Swift GRBs. This sample includes all Swift GRBs that were detected before 2012 August 1, whose X-ray afterglow extended well beyond 1 day and the estimated error in {alpha}{sub X} - {beta}{sub X} was {<=}0.25. The values of {alpha}{sub X} were extracted from the CB-model fits to the entire light curves of their X-ray afterglow while the spectral index was extracted by the Swift team from the time-integrated X-ray afterglow of these GRBs. We found that the distribution of the difference {alpha}{sub X} - {beta}{sub X} for these 315 Swift GRBs has three narrow peaks around 0, 1/2, and 1 whose widths are consistent with being due to the measurement errors, in agreement with the CB-model prediction.

  1. Prospects for Gamma-Ray Bursts detection by the Cherenkov Telescope Array

    E-Print Network [OSTI]

    ,

    2015-01-01

    The first Gamma-Ray Burst (GRB) catalog presented by the Fermi-Large Area Telescope (LAT) collaboration includes 28 GRBs, detected above 100 MeV over the first three years since the launch of the Fermi mission. However, more than 100 GRBs are expected to be found over a period of six years of data collection thanks to a new detection algorithm and to the development of a new LAT event reconstruction, the so-called "Pass 8." Our aim is to provide revised prospects for GRB alerts in the CTA era in light of these new LAT discoveries. We focus initially on the possibility of GRB detection with the Large Size Telescopes (LSTs). Moreover, we investigate the contribution of the Middle Size Telescopes (MSTs), which are crucial for the search of larger areas on short post trigger timescales. The study of different spectral components in the prompt and afterglow phase, and the limits on the Extragalactic background light are highlighted. Different strategies to repoint part of - or the entire array - are studied in det...

  2. Emission of Radio Waves in Gamma Ray Bursts and Axionic Boson Stars

    E-Print Network [OSTI]

    Aiichi Iwazaki

    1999-08-26

    We point out that the bursts of photons with the energy of the axion mass may appear coincidentally with gamma ray bursts if the gamma ray bursts are caused by collisions between neutron stars and axionic boson stars. In this mechanism, jets are formed in the collisions with large Lorentz factors $\\geq 10^2$. We explain qualitatively time-dependent complex structures of gamma ray bursts as well as the large energy problem. Therefore, with detection of the monochromatic photons we can test the model and determine the axion mass.

  3. Fast variability of TeV gamma-rays from the radio galaxy M 87

    E-Print Network [OSTI]

    HESS Collaboration; F. A. Aharonian

    2006-12-01

    The detection of fast variations of the TeV (10^12 eV) gamma-ray flux, on time-scales of days, from the nearby radio galaxy M 87 is reported. These variations are ~10 times faster than that observed in any other waveband and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma-rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed towards the observer.

  4. First search for neutrinos in correlation with gamma-ray bursts with the ANTARES neutrino telescope

    SciTech Connect (OSTI)

    NONE

    2013-03-01

    A search for neutrino-induced muons in correlation with a selection of 40 gamma-ray bursts that occurred in 2007 has been performed with the ANTARES neutrino telescope. During that period, the detector consisted of 5 detection lines. The ANTARES neutrino telescope is sensitive to TeV–PeV neutrinos that are predicted from gamma-ray bursts. No events were found in correlation with the prompt photon emission of the gamma-ray bursts and upper limits have been placed on the flux and fluence of neutrinos for different models.

  5. Sensitivity of the FERMI Detectors to Gamma-Ray Bursts from Evaporating Primordial Black Holes (PBHs)

    E-Print Network [OSTI]

    T. N. Ukwatta; Jane H. MacGibbon; W. C. Parke; K. S. Dhuga; S. Rhodes; A. Eskandarian; N. Gehrels; L. Maximon; D. C. Morris

    2010-03-23

    Primordial Black Holes (PBHs), which may have been created in the early Universe, are predicted to be detectable by their Hawking radiation. The Fermi Gamma-ray Space Telescope observatory offers increased sensitivity to the gamma-ray bursts produced by PBHs with an initial mass of $\\sim 5\\times 10^{14}$ g expiring today. PBHs are candidate progenitors of unidentified Gamma-Ray Bursts (GRBs) that lack X-ray afterglow. We propose spectral lag, which is the temporal delay between the high and low energy pulses, as an efficient method to identify PBH evaporation events with the Fermi Large Area Telescope (LAT).

  6. The rate and luminosity function of long Gamma Ray Bursts

    E-Print Network [OSTI]

    Pescalli, A; Salvaterra, R; Ghisellini, G; Vergani, S D; Nappo, F; Salafia, O S; Melandri, A; Covino, S; Götz, D

    2015-01-01

    We derive, adopting a direct method, the luminosity function and the formation rate of long Gamma Ray Bursts through a complete, flux-limited, sample of Swift bursts which has a high level of completeness in redshift z (~82%). We parametrise the redshift evolution of the GRB luminosity as L = L_0(1+ z)^k and we derive k = 2.5, consistently with recent estimates. The de-evolved luminosity function of GRBs can be represented by a broken power law with slopes a = -1.32 +- 0.21 and b = -1.84 +- 0.24 below and above, respectively, a characteristic break luminosity L_0,b = 10^51.45+-0.15 erg/s. Under the hypothesis of luminosity evolution we find that the GRB formation rate increases with redshift up to z~2, where it peaks, and then decreases in agreement with the shape of the cosmic star formation rate. We test the direct method through numerical simulations and we show that if it is applied to incomplete (both in redshift and/or flux) GRB samples it can misleadingly result in an excess of the GRB formation rate a...

  7. Broadband turbulent spectra in gamma-ray burst light curves

    SciTech Connect (OSTI)

    Van Putten, Maurice H. P. M.; Guidorzi, Cristiano; Frontera, Filippo

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  8. Gamma-ray burst polarization via Compton scattering process

    SciTech Connect (OSTI)

    Chang, Zhe; Lin, Hai-Nan; Jiang, Yunguo

    2014-03-01

    Synchrotron radiation and Compton scattering are widely accepted as the most likely emission mechanisms of some astrophysical phenomena, such as gamma-ray bursts (GRBs) and active galactic nuclei. The measurement of the polarization of photons provides a useful tool to distinguish different emission mechanisms and structures of the emission region. Based on the differential cross section of a polarized photon scattered by an unpolarized electron of any initial momentum, we derive an analytical formula of polarization for beamed photons scattered by isotropic electrons with a power-law distribution. Numerical calculations are carried out in four special cases: electrons at rest, Thomson limit, head-on collision, and monochromatic electrons. It is found that the maximum polarization can be as high as 100% for low energy photons, if the electrons are at rest. Although polarization is highly suppressed due to the isotropic electrons, a maximum value of ?10%-20% can still be achieved. The Compton scattering process can be used to explain the polarization of GRB 041219A and GRB 100826A.

  9. Radio Afterglows and Host Galaxies of Gamma-Ray Bursts

    E-Print Network [OSTI]

    Li, Long-Biao; Huang, Yong-Feng; Wu, Xue-Feng; Kong, Si-Wei; Li, Di; Chang, Heon-Young; Choi, Chul-Sung

    2015-01-01

    Considering the contribution of the emission from the host galaxies of gamma-ray bursts (GRBs) to the radio afterglows, we investigate the effect of host galaxies on observations statistically. For the three types of events, e.g. low-luminosity, standard and high-luminosity GRBs, it is found that a tight correlation exists between the ratio of the radio flux (RRF) of host galaxy to the total radio peak emission and the observational frequency. Especially, toward lower frequencies, the contribution from the host increases significantly. The correlation can be used to get a useful estimate for the radio brightness of those host galaxies which only have very limited radio afterglow data. Using this prediction, we re-considered the theoretical radio afterglow light curves for four kinds of events, i.e. high-luminosity, low-luminosity, standard and failed GRBs, taking into account the contribution from the host galaxies and aiming at exploring the detectability of these events by the Five-hundred-meter Aperture Sp...

  10. Probing Long Gamma Ray Bursts progenitor mass by Gravitational Waves

    E-Print Network [OSTI]

    De Laurentis, Mariafelicia; Dainotti, Maria Giovanna; Milano, Leopoldo

    2015-01-01

    In this work we present a procedure to infer the mass of progenitors and remnants of Gamma Ray Bursts (GRB), starting from the observed energy $E_{iso}^{GRB}$ emitted isotropically and considering the associated emission of Gravitational Waves (GW) $ E_{iso}^{GW}$ in the different phases. We assume that the GW energy of the progenitor $E_{PROG}^{GW}$ is emitted partially during a star collapse, and the residual energy is related to the GW energy emitted by the remnant. We take a sample of $237$ Long GRB, and use an hybrid Montecarlo procedure to explore, for each of them, a region of possible solutions of $ E_{iso}^{GW}$ as a function of the masses, radii, oblateness, rotation frequencies of progenitor and remnant and the fraction of energy $k$ emitted as GW by the GRB. We discriminate between a Neutron Star (NS) or Black Hole (BH) for the remnant and obtain interesting values for the GW emitted by the remnant NS or BH, for the conversion factor $k$ of and for the masses and radii of GRB progenitor stars. We ...

  11. Bismuth-Loaded Polymer Scintillators for Gamma Ray Spectroscopy

    SciTech Connect (OSTI)

    Rupert, B L; Cherepy, N J; Sturm, B W; Sanner, R D; Dai, Z; Payne, S A

    2011-04-11

    We synthesize a series of polyvinylcarbazole monoliths containing varying loadings of triphenyl bismuth as a high-Z dopant and varying fluors, either organic or organometallic, in order to study their use as scintillators capable of gamma ray spectroscopy. A trend of increasing bismuth loading resulting in a better-resolved photopeak is observed. For PVK parts with no fluor or a standard organic fluor, diphenylanthracene, increasing bismuth loading results in decreasing light yield while with samples 1 or 3 % by weight of the spin-orbit coupling organometallic fluor FIrpic, which emits light from both singlet and triple excitons, show increasing light yield with increasing bismuth loading. Our best performing PVK/ BiPh{sub 3}/FIrpic scintillator with 40 wt % BiPh3 and 3 wt % FIrpic has an emission maximum of 500 nm, a light yield of {approx}30,000 photons/MeV, and energy resolution better than 7% FWHM at 662 keV. Replacing the Ir complex with an equal weight of diphenylanthracene produces a sample with a light yield of {approx}6,000 photons/MeV, with an emission maximum at 420 nm and energy resolution of 9% at 662 keV. Transmission electron microscopy studies show that the BiPh{sub 3} forms small clusters of approximately 5 nm diameter.

  12. Gamma-ray burst supernovae as standardizable candles

    SciTech Connect (OSTI)

    Cano, Z., E-mail: zewcano@gmail.com [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Reykjavik (Iceland)

    2014-10-20

    A long-duration gamma-ray burst (GRB) marks the violent end of a massive star. GRBs are rare in the universe, and their progenitor stars are thought to possess unique physical properties such as low metal content and rapid rotation, while the supernovae (SNe) that are associated with GRBs are expected to be highly aspherical. To date, it has been unclear whether GRB-SNe could be used as standardizable candles, with contrasting conclusions found by different teams. In this paper, I present evidence that GRB-SNe have the potential to be used as standardizable candles and show that a statistically significant relation exists between the brightness and width of their decomposed light curves relative to a template SN. Every single nearby spectroscopically identified GRB-SN for which the rest frame and host contributions have been accurately determined follows this relation. Additionally, it is shown that not only GRB-SNe, but perhaps all SNe whose explosions are powered by a central engine may eventually be used as a standardizable candle. Finally, I suggest that the use of GRB-SNe as standardizable candles likely arises from a combination of the viewing angle and similar explosion geometry in each event, the latter of which is influenced by the explosion mechanism of GRB-SNe.

  13. Identifying high-redshift gamma-ray bursts with RATIR

    SciTech Connect (OSTI)

    Littlejohns, O. M.; Butler, N. R. [School of Earth and Space Exploration, Arizona State University, AZ 85287 (United States); Cucchiara, A. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Watson, A. M.; Lee, W. H.; Richer, M. G.; De Diego, J. A.; Georgiev, L.; González, J.; Román-Zúńiga, C. G. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, 04510 México, D. F. (Mexico); Kutyrev, A. S.; Troja, E.; Gehrels, N.; Moseley, H. [NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Klein, C. R.; Fox, O. D.; Bloom, J. S. [Astronomy Department, University of California, Berkeley, CA 94720-7450 (United States); Prochaska, J. X.; Ramirez-Ruiz, E. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2014-07-01

    We present a template-fitting algorithm for determining photometric redshifts, z {sub phot}, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z {sub phot} < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z {sub phot} in the ranges of 4 < z {sub phot} ? 8 and 9 < z {sub phot} < 10 and can robustly determine when z {sub phot} > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z {sub phot} < 4 when z {sub sim} > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

  14. DIFFUSE PeV NEUTRINOS FROM GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Liu, Ruo-Yu; Wang, Xiang-Yu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)] [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-04-01

    The IceCube Collaboration recently reported the potential detection of two cascade neutrino events in the energy range 1-10 PeV. We study the possibility that these PeV neutrinos are produced by gamma-ray bursts (GRBs), paying special attention to the contribution by untriggered GRBs that elude detection due to their low photon flux. Based on the luminosity function, rate distribution with redshift and spectral properties of GRBs, we generate, using a Monte Carlo simulation, a GRB sample that reproduces the observed fluence distribution of Fermi/GBM GRBs and an accompanying sample of untriggered GRBs simultaneously. The neutrino flux of every individual GRB is calculated in the standard internal shock scenario, so that the accumulative flux of the whole samples can be obtained. We find that the neutrino flux in PeV energies produced by untriggered GRBs is about two times higher than that produced by the triggered ones. Considering the existing IceCube limit on the neutrino flux of triggered GRBs, we find that the total flux of triggered and untriggered GRBs can reach at most a level of {approx}10{sup -9} GeV cm{sup -2} s{sup -1} sr{sup -1}, which is insufficient to account for the reported two PeV neutrinos. Possible contributions to diffuse neutrinos by low-luminosity GRBs and the earliest population of GRBs are also discussed.

  15. Delayed energy injection model for gamma-ray burst afterglows

    SciTech Connect (OSTI)

    Geng, J. J.; Huang, Y. F.; Yu, Y. B. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: hyf@nju.edu.cn, E-mail: xfwu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2013-12-10

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) are widely believed to be associated with the later activation of the central engine. Some models of energy injection involve a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time ?t {sub fb}. Thus, we propose a delayed energy injection model. The delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will 'generate' a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy; this indicates that GRBs accompanied with fall-back material may be associated with a low energy supernova so that the fraction of the envelope can survive during eruption. The fall-back time can give meaningful information on the properties of GRB progenitor stars.

  16. Gamma-ray burst flares: X-ray flaring. II

    SciTech Connect (OSTI)

    Swenson, C. A.; Roming, P. W. A., E-mail: cswenson@astro.psu.edu [Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

    2014-06-10

    We present a catalog of 498 flaring periods found in gamma-ray burst (GRB) light curves taken from the online Swift X-Ray Telescope GRB Catalogue. We analyzed 680 individual light curves using a flare detection method developed and used on our UV/optical GRB Flare Catalog. This method makes use of the Bayesian Information Criterion to analyze the residuals of fitted GRB light curves and statistically determines the optimal fit to the light curve residuals in an attempt to identify any additional features. These features, which we classify as flares, are identified by iteratively adding additional 'breaks' to the light curve. We find evidence of flaring in 326 of the analyzed light curves. For those light curves with flares, we find an average number of ?1.5 flares per GRB. As with the UV/optical, flaring in our sample is generally confined to the first 1000 s of the afterglow, but can be detected to beyond 10{sup 5} s. Only ?50% of the detected flares follow the 'classical' definition of ?t/t ? 0.5, with many of the largest flares exceeding this value.

  17. Fast radio burst/gamma-ray burst cosmography

    SciTech Connect (OSTI)

    Gao, He; Zhang, Bing [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States); Li, Zhuo, E-mail: gaohe@physics.unlv.edu, E-mail: zhang@physics.unlv.edu, E-mail: zhuo.li@pku.edu.cn [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)

    2014-06-20

    Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measures (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DM{sub IGM} as a function of z and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with several tens of FRB/GRB systems potentially detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with Type Ia supernova (SN Ia) data, unprecedented constraints on the dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value and luminosity distance (D {sub L}(z)) is insensitive to dark energy models. This gives the prospect of applying SN Ia data to calibrate using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.

  18. Gamma-ray burst spectrum with decaying magnetic field

    SciTech Connect (OSTI)

    Zhao, Xiaohong; Bai, Jinming [Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming (China); Li, Zhuo [Department of Astronomy and Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Liu, Xuewen; Zhang, Bin-bin; Mészáros, Peter, E-mail: zhaoxh@ynao.ac.cn, E-mail: zhuo.li@pku.edu.cn [Department of Astronomy and Astrophysics and Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2014-01-01

    In the internal shock model for gamma-ray bursts (GRBs), the synchrotron spectrum from the fast cooling electrons in a homogeneous downstream magnetic field (MF) is too soft to produce the low-energy slope of GRB spectra. However, the MF may decay downstream with distance from the shock front. Here we show that the synchrotron spectrum becomes harder if electrons undergo synchrotron and inverse-Compton cooling in a decaying MF. To reconcile this with the typical GRB spectrum with low-energy slope ?F {sub ?}??, the postshock MF decay time must be comparable to the cooling time of the bulk electrons (corresponding to a MF decaying length typically of ?10{sup 5} skin depths); that the inverse-Compton cooling should dominate synchrotron cooling after the MF decay time; and/or that the MF decays with comoving time roughly as B?t {sup –1.5}. An internal shock synchrotron model with a decaying MF can account for the majority of GRBs with low-energy slopes not harder than ?{sup 4/3}.

  19. REDSHIFT CATALOG FOR SWIFT LONG GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Xiao Limin; Schaefer, Bradley E., E-mail: lxiao1@lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2011-04-20

    We present a catalog of the redshifts for most long-duration gamma-ray bursts (GRBs) by Swift from 2004 December 20 to 2008 July 23 (258 bursts in total). All available information is collected, including spectroscopic redshifts, photometric redshift limits, and redshifts calculated from various luminosity relations. Error bars for the redshifts derived from the luminosity relations are asymmetric, with tails extended to the high-redshift end, and this effect is evaluated by looking at the 30% of Swift bursts with spectroscopic redshifts. A simulation is performed to eliminate this asymmetric effect, and the resultant redshift distribution is deconvolved. We test and confirm this simulation on the sample of bursts with known spectroscopic redshifts and then apply it to the 70% of Swift bursts that do not have spectroscopic measures. A final intrinsic redshift distribution is then made for almost all Swift bursts, and the efficiency of the spectroscopic detections is evaluated. The efficiency of spectroscopic redshifts varies from near unity at low redshift to 0.5 at z = 1, to near 0.3 at z = 4, and to 0.1 at z = 6. We also find that the fraction of GRBs with z>5 is {approx}10%, and this fraction is compared with simulations from a cosmological model.

  20. Detecting an association between Gamma Ray and Gravitational Wave Bursts

    E-Print Network [OSTI]

    Lee Samuel Finn; Soumya D. Mohanty; Joseph D. Romano

    1999-03-30

    If $\\gamma$-ray bursts (GRBs) are accompanied by gravitational wave bursts (GWBs) the correlated output of two gravitational wave detectors evaluated in the moments just prior to a GRB will differ from that evaluated at times not associated with a GRB. We can test for this difference independently of any model of the GWB signal waveform. If we invoke a model for the GRB source population and GWB radiation spectral density we can find a confidence interval or upper limit on the root-mean-square GWB signal amplitude in the detector waveband. To illustrate we adopt a simple, physically motivated model and estimate that initial LIGO detector observations coincident with 1000 GRBs could lead us to exclude, with 95% confidence, associated GWBs with $h_{RMS} \\gtrsim 1.7 \\times 10^{-22}$. This result does not require the detector noise be Gaussian or that any inter-detector correlated noise be measured or measurable; it does not require advanced or a priori knowledge of the source waveform; and the limits obtained on the wave-strength improve with the number of observed GRBs.

  1. Gravitational and magnetosonic waves in gamma-ray bursts

    E-Print Network [OSTI]

    Joachim Moortgat; Jan Kuijpers

    2003-02-13

    One of the possible sources of gamma-ray bursts are merging, compact neutronstar binaries. More than 90% of the binding energy of such a binary is released in the form of gravitational waves (GWs) in the last few seconds of the spiral-in phase before the formation of a black hole. In this article we investigate whether a fraction of this GW-energy is transferred to magnetohydrodynamic waves in the magnetized plasma wind around the binary. Using the 3+1 orthonormal tedrad formalism, we study the propagation of a monochromatic, plane fronted, linearly polarized GW perpendicular to the ambient magnetic field in an ultra-relativistic wind, first in the comoving and then in the observer frame. A closed set of general relativistic magnetohydrodynamic equations is derived in the form of conservation laws for electric charge, matter energy, momentum and magnetic energy densities. We linearize these equations under the action of a monochromatic GW, which acts as a driver and find that fast magneto-acoustic waves grow, with amplitudes proportional to the GW amplitude and frequency and the strength of the background magnetic field.

  2. Neutrinos and Nucleosynthesis in Gamma-Ray Burst Accretion Disks

    E-Print Network [OSTI]

    R. Surman; G. C. McLaughlin

    2003-11-24

    We calculate the nuclear composition of matter in accretion disks surrounding stellar mass black holes as are thought to accompany gamma-ray bursts (GRBs). We follow a mass element in the accretion disk starting at the point of nuclear dissociation and calculate the evolution of the electron fraction due to electron, positron, electron neutrino and electron antineutrino captures. We find that the neutronization of the disk material by electron capture can be reversed by neutrino interactions in the inner regions of disks with accretion rates of 1 M_solar/s and higher. For these cases the inner disk regions are optically thick to neutrinos, and so to estimate the emitted neutrino fluxes we find the surface of last scattering for the neutrinos (the equivalent of the proto-neutron star neutrinosphere) for each optically thick disk model. We also estimate the influence of neutrino interactions on the neutron-to-proton ratio in outflows from GRB accretion disks, and find it can be significant even when the disk is optically thin to neutrinos.

  3. MAGNETIZATION DEGREE OF GAMMA-RAY BURST FIREBALLS: NUMERICAL STUDY

    SciTech Connect (OSTI)

    Harrison, Richard; Kobayashi, Shiho, E-mail: R.M.Harrison@2006.ljmu.ac.uk [Astrophysics Research Institute, Liverpool John Moores University, Liverpool, L3 5RF (United Kingdom)

    2013-08-01

    The relative strength between forward and reverse shock emission in early gamma-ray burst (GRB) afterglow reflects that of magnetic energy densities in the two shock regions. We numerically show that with the current standard treatment, the fireball magnetization is underestimated by up to two orders of magnitude. This discrepancy is especially large in the sub-relativistic reverse shock regime (i.e., the thin shell and intermediate regime), where most optical flashes were detected. We provide new analytic estimates of the reverse shock emission based on a better shock approximation, which well describe numerical results in the intermediate regime. We show that the reverse shock temperature at the onset of afterglow is constant, ( {Gamma}-bar{sub d}-1){approx}8 Multiplication-Sign 10{sup -2}, when the dimensionless parameter {xi}{sub 0} is more than several. Our approach is applied to case studies of GRB 990123 and 090102, and we find that magnetic fields in the fireballs are even stronger than previously believed. However, these events are still likely to be due to a baryonic jet with {sigma} {approx} 10{sup -3} for GRB 990123 and {approx}3 Multiplication-Sign 10{sup -4} to 3 for GRB 090102.

  4. Optical afterglows of gamma-ray bursts: a bimodal distribution?"

    E-Print Network [OSTI]

    Nardini Marco; Ghisellini Gabriele; Ghirlanda Giancarlo

    2007-10-12

    The luminosities of the optical afterglows of Gamma Ray Bursts, 12 hours (rest frame time) after the trigger, show a surprising clustering, with a minority of events being at a significant smaller luminosity. If real, this dichotomy would be a crucial clue to understand the nature of optically dark afterglows, i.e. bursts that are detected in the X-ray band, but not in the optical. We investigate this issue by studying bursts of the pre-Swift era, both detected and undetected in the optical. The limiting magnitudes of the undetected ones are used to construct the probability that a generic bursts is observed down to a given magnitude limit. Then, by simulating a large number of bursts with pre-assigned characteristics, we can compare the properties of the observed optical luminosity distribution with the simulated one. Our results suggest that the hints of bimodality present in the observed distribution reflects a real bimodality: either the optical luminosity distributions of bursts is intrinsically bimodal, or there exists a population of bursts with a quite significant grey absorption, i.e. wavelength independent extinction. This population of intrinsically weak or grey-absorbed events can be associated to dark bursts.

  5. Energy Injection in Gamma-ray Burst Afterglows

    E-Print Network [OSTI]

    Laskar, Tanmoy; Margutti, Raffaella; Perley, Daniel; Zauderer, B Ashley; Sari, Re'em; Fong, Wen-fai

    2015-01-01

    We present multi-wavelength observations and modeling of Gamma-ray Bursts (GRBs) that exhibit a simultaneous re-brightening in their X-ray and optical light curves, and are also detected at radio wavelengths. We show that the re-brightening episodes can be modeled by injection of energy into the blastwave and that in all cases the energy injection rate falls within the theoretical bounds expected for a distribution of energy with ejecta Lorentz factor. Our measured values of the circumburst density, jet opening angle, and beaming corrected kinetic energy are consistent with the distribution of these parameters for long-duration GRBs at both z~1 and z>6, suggesting that the jet launching mechanism and environment of these events are similar to that of GRBs that do not have bumps in their light curves. However, events exhibiting re-brightening episodes have lower radiative efficiencies than average, suggesting that a majority of the kinetic energy of the outflow is carried by slow-moving ejecta, which is furthe...

  6. The Energy Distribution of Gamma-Ray Bursts

    E-Print Network [OSTI]

    David L. Band

    2001-05-15

    The distribution of the apparent total energy emitted by a gamma-ray burst reflects not only the distribution of the energy actually released by the burst engine, but also the distribution of beaming angles. Using the observed energy fluences, the detection thresholds and burst redshifts for three burst samples, I calculate the best-fit parameters for lognormal and power-law distributions of the apparent total energy. Two of the samples include a small number of bursts with spectroscopic redshifts, while the third sample has 220 bursts with redshifts determined by the proposed variability-luminosity correlation. I find different sets of parameter values for the three burst samples. The Bayesian odds ratio cannot distinguish between the two model distribution functions for the two smaller burst samples with spectroscopic redshifts, but does favor the lognormal distribution for the larger sample with variability-derived redshifts. The data do not rule out a distribution with a low energy tail which is currently unobservable. I find that neglecting the burst detection threshold biases the fitted distribution to be narrower with a higher average value than the true distribution; this demonstrates the importance of determining and reporting the effective detection threshold for bursts in a sample.

  7. Gamma-rays from halos around stars and the Sun

    E-Print Network [OSTI]

    Elena Orlando; Andrew Strong

    2006-10-31

    Inverse Compton scattering by relativistic electrons produces a major component of the diffuse emission from the Galaxy. The photon fields involved are the cosmic microwave background and the interstellar radiation field from stars and dust. Calculations of the inverse Compton distribution have usually assumed a smooth ISRF, but in fact a large part of the Galactic luminosity comes from the most luminous stars which are rare. Therefore we expect the ISRF, and hence the inverse Compton emission, to be clumpy at some level which could be detectable by instruments such as GLAST. Even individual nearby luminous stars could be detectable assuming just the normal cosmic-ray electron spectrum. We present the basic formalism required and give possible candidate stars to be detected, and make predictions for GLAST. Then we apply the formalism to OB associations and the Sun, showing that the IC emission produced is not negligible compared to the sensitivity of current or coming detectors. We estimate that the gamma-ray flux from the halo around the Sun contributes to the diffuse background emission at about the few percent level.

  8. Robust Limits on Lorentz Violation from Gamma-Ray Bursts

    E-Print Network [OSTI]

    John Ellis; Nick E. Mavromatos; Dimitri V. Nanopoulos; Alexander S. Sakharov; Edward K. G. Sarkisyan

    2005-10-06

    We constrain the possibility of a non-trivial refractive index in free space corresponding to an energy-dependent velocity of light: c(E) \\simeq c_0 (1 - E/M), where M is a mass scale that might represent effect of quantum-gravitational space-time foam, using the arrival times of sharp features observed in the intensities of radiation with different energies from a large sample of gamma-ray bursters (GRBs) with known redshifts. We use wavelet techniques to identify genuine features, which we confirm in simulations with artificial added noise. Using the weighted averages of the time-lags calculated using correlated features in all the GRB light curves, we find a systematic tendency for more energetic photons to arrive earlier. However, there is a very strong correlation between the parameters characterizing an intrinsic time-lag at the source and a distance-dependent propagation effect. Moreover, the significance of the earlier arrival times is less evident for a subsample of more robust spectral structures. Allowing for intrinsic stochastic time-lags in these features, we establish a statistically robust lower limit: M > 0.9x10^{16} GeV on the scale of violation of Lorentz invariance.

  9. Gamma-ray imaging system. Innovative technology summary report

    SciTech Connect (OSTI)

    NONE

    1998-11-01

    The RadScan 600 gamma-ray imaging system is designed to survey large surface areas for radiological contamination with accuracy and efficiency. The resulting survey data are clear, concise, and precise in describing how much contamination is present at exact locations. Data can be permanently stored electronically and on video tape, making storage and retrieval economical and efficient. This technology can perform accurate measurements in high radiation contamination areas while minimizing worker exposure. The RadScan 600 system is a safe and effective alternative to hand-held radiation detection devices. Performance data of the demonstrated survey area of the RadScan 600 system versus the baseline, which is the hand-held radiation detection devices (RO-2 and RO-7) for a given survey, production rate is 72% of the baseline. It should be noted that the innovative technology provides 100% coverage at a unit cost of $8.64/m{sup 2} versus a static measurement of a unit cost of $1.61/m{sup 2} for the baseline.

  10. Re-born fireballs in Gamma-Ray Bursts

    E-Print Network [OSTI]

    Ghisellini, G; Ghirlanda, G; Firmani, C; Nava, L

    2007-01-01

    We consider the interaction between a relativistic fireball and material assumed to be still located just outside the progenitor star. Only a small fraction of the expected mass is sufficient to efficiently decelerate the fireball, leading to dissipation of most of its kinetic energy. Since the scattering optical depths are still large at distances comparable to the progenitor radius, the dissipated energy is trapped in the system, accelerating it to relativistic velocities. The process resembles the birth of another fireball at radii R~1e11 cm, not far from the transparency radius, and with a starting bulk Lorentz factors Gamma_c~10. As seen in the observer frame, this "re--generated" fireball appears collimated within an angle theta_j=1/Gamma_c. If the central engine works intermittently, the funnel can, at least partially, refill and the process can repeat itself. We discuss how this idea can help solving some open issues of the more conventional internal shock scenario for interpreting the Gamma-Ray Burst...

  11. Re-born fireballs in Gamma-Ray Bursts

    E-Print Network [OSTI]

    G. Ghisellini; A. Celotti; G. Ghirlanda; C. Firmani; L. Nava

    2007-09-12

    We consider the interaction between a relativistic fireball and material assumed to be still located just outside the progenitor star. Only a small fraction of the expected mass is sufficient to efficiently decelerate the fireball, leading to dissipation of most of its kinetic energy. Since the scattering optical depths are still large at distances comparable to the progenitor radius, the dissipated energy is trapped in the system, accelerating it to relativistic velocities. The process resembles the birth of another fireball at radii R~1e11 cm, not far from the transparency radius, and with a starting bulk Lorentz factors Gamma_c~10. As seen in the observer frame, this "re--generated" fireball appears collimated within an angle theta_j=1/Gamma_c. If the central engine works intermittently, the funnel can, at least partially, refill and the process can repeat itself. We discuss how this idea can help solving some open issues of the more conventional internal shock scenario for interpreting the Gamma-Ray Burst properties.

  12. Gamma-Rays from Large Scale Structure Formation and the Warm-Hot Intergalactic Medium: Cosmic Baryometry with Gamma-Rays

    E-Print Network [OSTI]

    Susumu Inoue; Masahiro Nagashima

    2005-02-17

    It is shown that inverse Compton gamma-rays from electrons accelerated in large scale structure formation shocks can be crucially affected by non-gravitational effects such as radiative cooling and galaxy formation, with corresponding uncertainties by an order of magnitude in either the gamma-ray source counts or the extragalactic background contribution. However, this also implies that such gamma-rays may in the near future provide us with valuable information about the fraction of cosmic baryons in different forms, particularly the warm-hot intergalactic medium where the majority of the baryons in the universe are believed to reside. We address this problem in a simple way through semi-analytic modeling of structure formation shocks which self-consistently treats merger and accretion shocks.

  13. GRB 110709A, 111117A, AND 120107A: FAINT HIGH-ENERGY GAMMA-RAY PHOTON EMISSION FROM FERMI-LAT OBSERVATIONS AND DEMOGRAPHIC IMPLICATIONS

    SciTech Connect (OSTI)

    Zheng Weikang; Akerlof, Carl W.; McKay, Timothy A. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States); Pandey, Shashi B. [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263129 (India); Zhang Binbin [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Zhang Bing [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Sakamoto, Takanori, E-mail: zwk@umich.edu [Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-01

    Launched on 2008 June 11, the Large Area Telescope (LAT) instrument on board the Fermi Gamma-ray Space Telescope has provided a rare opportunity to study high-energy photon emission from gamma-ray bursts (GRBs). Although the majority of such events (27) have been identified by the Fermi-LAT Collaboration, four were uncovered by using more sensitive statistical techniques. In this paper, we continue our earlier work by finding three more GRBs associated with high-energy photon emission, GRB 110709A, 111117A, and 120107A. To systematize our matched filter approach, a pipeline has been developed to identify these objects in nearly real time. GRB 120107A is the first product of this analysis procedure. Despite the reduced threshold for identification, the number of GRB events has not increased significantly. This relative dearth of events with low photon number prompted a study of the apparent photon number distribution. We find an extremely good fit to a simple power law with an exponent of -1.8 {+-} 0.3 for the differential distribution. As might be expected, there is a substantial correlation between the number of lower energy photons detected by the Gamma-ray Burst Monitor (GBM) and the number observed by LAT. Thus, high-energy photon emission is associated with some but not all of the brighter GBM events. Deeper studies of the properties of the small population of high-energy emitting bursts may eventually yield a better understanding of these entire phenomena.

  14. OPTIMIZATION OF VIRTUAL FRISCH-GRID CdZnTe DETECTOR DESIGNS FOR IMAGING AND SPECTROSCOPY OF GAMMA RAYS.

    SciTech Connect (OSTI)

    BOLOTNIKOV,A.E.; ABDUL-JABBAR, N.M.; BABALOLA, S.; CAMARDA, G.S.; CUI, Y.; HOSSAIN, A.; JACKSON, E.; JACKSON, H.; JAMES, J.R.; LURYI, A.L.; JAMES, R.B.

    2007-08-21

    In the past, various virtual Frisch-grid designs have been proposed for cadmium zinc telluride (CZT) and other compound semiconductor detectors. These include three-terminal, semi-spherical, CAPture, Frisch-ring, capacitive Frisch-grid and pixel devices (along with their modifications). Among them, the Frisch-grid design employing a non-contacting ring extended over the entire side surfaces of parallelepiped-shaped CZT crystals is the most promising. The defect-free parallelepiped-shaped crystals with typical dimensions of 5x5{approx}12 mm3 are easy to produce and can be arranged into large arrays used for imaging and gamma-ray spectroscopy. In this paper, we report on further advances of the virtual Frisch-grid detector design for the parallelepiped-shaped CZT crystals. Both the experimental testing and modeling results are described.

  15. Fermi Observations of High-Energy Gamma-Ray Emission From GRB...

    Office of Scientific and Technical Information (OSTI)

    From GRB 080825C Citation Details In-Document Search Title: Fermi Observations of High-Energy Gamma-Ray Emission From GRB 080825C Authors: Abdo, A.A. ; Naval Research Lab,...

  16. Fermi Observations of High-Energy Gamma-Ray Emission from GRB...

    Office of Scientific and Technical Information (OSTI)

    from GRB 080916C Citation Details In-Document Search Title: Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C Authors: Abdo, Aous A. ; Naval Research...

  17. Fermi Gamma-Ray Space Telescope: High-Energy Results From the...

    Office of Scientific and Technical Information (OSTI)

    Gamma-Ray Space Telescope: High-Energy Results From the First Year Michelson, P.F.; KIPAC, Menlo Park; Atwood, W.B.; Ritz, S.; UC, Santa Cruz UC, Santa Cruz, Phys. Dept....

  18. Constraints on Gamma-ray Emission from the Galactic Plane at 300 TeV

    E-Print Network [OSTI]

    A. Borione; M. A. Catanese; M. C. Chantell; C. E. Covault; J. W. Cronin; B. E. Fick; L. F. Fortson; J. Fowler; M. A. K. Glasmacher; K. D. Green; D. B. Kieda; J. Matthews; B. J. Newport; D. Nitz; R. A. Ong; S. Oser; D. Sinclair; J. C. van der Velde

    1997-03-10

    We describe a new search for diffuse ultrahigh energy gamma-ray emission associated with molecular clouds in the galactic disk. The Chicago Air Shower Array (CASA), operating in coincidence with the Michigan muon array (MIA), has recorded over 2.2 x 10^{9} air showers from April 4, 1990 to October 7, 1995. We search for gamma rays based upon the muon content of air showers arriving from the direction of the galactic plane. We find no significant evidence for diffuse gamma-ray emission, and we set an upper limit on the ratio of gamma rays to normal hadronic cosmic rays at less than 2.4 x 10^{-5} at 310 TeV (90% confidence limit) from the galactic plane region: (50 degrees energies is likely to be dominated by the decay of neutral pions resulting from cosmic rays interactions with passive target gas molecules.

  19. Expectations for the hard x-ray continuum and gamma-ray line...

    Office of Scientific and Technical Information (OSTI)

    continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the sup 56Ni yield...

  20. Determining the jet opening-angle of gamma-ray bursts

    E-Print Network [OSTI]

    McEvoy, Erica Lynn, 1981-

    2004-01-01

    There is growing scientific agreement that at least some cosmic gamma-ray bursts (GRBs) coincide with the deaths of rapidly rotating massive stars - dubbed "hyper-novae." In 1987, a supernova (SN 1987A) was detected in the ...

  1. EXPLORING SHORT GAMMA-RAY BURSTS AS GRAVITATIONAL-WAVE STANDARD SIRENS

    E-Print Network [OSTI]

    Hughes, Scott A.

    Recent observations support the hypothesis that a large fraction of "short-hard" gamma-ray bursts (SHBs) are associated with the inspiral and merger of compact binaries. Since gravitational-wave (GW) measurements of ...

  2. How Gravitational-wave Observations Can Shape the Gamma-ray Burst Paradigm

    E-Print Network [OSTI]

    Imre Bartos; Patrick Brady; Szabolcs Marka

    2012-12-11

    By reaching through shrouding blastwaves, efficiently discovering off-axis events, and probing the central engine at work, gravitational wave (GW) observations will soon revolutionize the study of gamma-ray bursts. Already, analyses of GW data targeting gamma-ray bursts have helped constrain the central engines of selected events. Advanced GW detectors with significantly improved sensitivities are under construction. After outlining the GW emission mechanisms from gamma-ray burst progenitors (binary coalescences, stellar core collapses, magnetars, and others) that may be detectable with advanced detectors, we review how GWs will improve our understanding of gamma-ray burst central engines, their astrophysical formation channels, and the prospects and methods for different search strategies. We place special emphasis on multimessenger searches. To achieve the most scientific benefit, GW, electromagnetic, and neutrino observations should be combined to provide greater discriminating power and science reach.

  3. STUDY OF ELECTRON ANTI-NEUTRINOS ASSOCIATED WITH GAMMA-RAY BURSTS USING KamLAND

    E-Print Network [OSTI]

    Winslow, Lindley

    We search for electron anti-neutrinos ([bar over ?][subscript e]) from long- and short-duration gamma-ray bursts (GRBs) using data taken by the Kamioka Liquid Scintillator Anti-Neutrino Detector (KamLAND) from 2002 August ...

  4. Studies of intrinsic properties of gamma ray bursts detected by the HETE-II satellite

    E-Print Network [OSTI]

    Csatorday, Peter, 1973-

    2007-01-01

    Analysis of HETE-II data is discussed with the aim of understanding the intrinsic properties of gamma-ray bursts (GRBs). A technique is developed that allows the simultaneous estimation of source and background counts ...

  5. Temperatures and Natural Gamma-Ray Logs Obtained in 1986 from...

    Open Energy Info (EERE)

    and following drilling and possibly to ground shaking associated with present and past seismic activity in the Long Valley region.Natural gamma-ray logs obtained on four...

  6. Did a gamma-ray burst initiate the late Ordovician mass extinction?

    E-Print Network [OSTI]

    Melott, Adrian L.; Lieberman, Bruce S.; Laird, C. M.; Martin, Larry D.; Medvedev, Mikhail V.; Thomas, Brian C.; Cannizzo, J. K.; Gehrels, N.; Jackman, C. H.

    2004-01-01

    Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur...

  7. Method for on-line evaluation of materials using prompt gamma ray analysis

    DOE Patents [OSTI]

    Akers, Douglas W. (Idaho Falls, ID)

    2009-12-08

    A method for evaluating a material specimen comprises: Mounting a neutron source and a detector adjacent the material specimen; bombarding the material specimen with neutrons from the neutron source to create prompt gamma rays within the material specimen, some of the prompt gamma rays being emitted from the material specimen, some of the prompt gamma rays resulting in the formation of positrons within the material specimen by pair production; collecting positron annihilation data by detecting with the detector at least one emitted annihilation gamma ray resulting from the annihilation of a positron; storing the positron annihilation data on a data storage system for later retrieval and processing; and continuing to collect and store positron annihilation data, the continued collected and stored positron annihilation data being indicative of an accumulation of lattice damage over time.

  8. Automatic quenching of high energy gamma-ray sources by synchrotron photons

    E-Print Network [OSTI]

    L. Stawarz; J. G. Kirk

    2007-03-26

    We investigate a magnetized plasma in which injected high energy gamma-rays annihilate on a soft photon field, that is provided by the synchrotron radiation of the created pairs. For a very wide range of magnetic fields, this process involves gamma-rays between 0.3 GeV and 30 TeV. We derive a simple dynamical system for this process, analyze its stability to runaway production of soft photons and paris, and find conditions for it to automatically quench by reaching a steady state with an optical depth to photon-photon annihilation larger than unity. We discuss applications to broad-band gamma-ray emitters, in particular supermassive black holes. Automatic quenching limits the gamma-ray luminosity of these objects and predicts substantial pair loading of the jets of less active sources.

  9. U235: A Gamma Ray Analysis Code for Uranium Isotopic Determination

    Office of Scientific and Technical Information (OSTI)

    5727 U235: A Gamma Ray Analysis Code for Uranium Isotopic Determination DeLynn Clark December 1996 may not be those of the Laboratory. Work performed under the auspices of the U S...

  10. AMON Searches for Jointly-Emitting Neutrino + Gamma-Ray Transients

    E-Print Network [OSTI]

    Keivani, A; Teši?, G; Cowen, D F; Fixelle, J

    2015-01-01

    We present the results of archival coincidence analyses using public neutrino data from the 40-string configuration of IceCube (IC40) and contemporaneous public gamma-ray data from Fermi LAT. Our analyses have the potential to discover statistically significant coincidences between high-energy neutrino and gamma-ray signals, and hence, possible jointly-emitting neutrino/gamma-ray transients. This work is an example of more general multimessenger studies that the Astrophysical Multimessenger Observatory Network (AMON) aims to perform. AMON is currently under development and will link multiple running and future high-energy neutrino, cosmic ray and follow-up observatories as well as gravitational wave facilities. This single network will enable near real-time coincidence searches for multimessenger astrophysical transients and their electromagnetic counterparts. We will present the component high-energy neutrino and gamma-ray datasets, the statistical approaches that we used, and the results of analyses of the ...

  11. A search for optical counterparts of gamma-ray bursts. Final report

    SciTech Connect (OSTI)

    Park, Hye-Sook

    1995-03-09

    Gamma Ray Bursts (GRBS) are mysterious flashes of gamma rays lasting several tens to hundreds of seconds that occur approximately once per day. NASA launched the orbiting Compton Gamma Ray Observatory to study GRBs and other gamma ray phenomena. CGRO carries the Burst and Transient Experiment (BATSE) specifically to study GRBS. Although BATSE has collected data on over 600 GRBS, and confirmed that GRBs are localized, high intensity point sources of MeV gamma rays distributed isotropically in the sky, the nature and origin of GRBs remains a fundamental problem in astrophysics. BATSE`s 8 gamma ray sensors located on the comers of the box shaped CGRO can detect the onset of GRBs and record their intensity and energy spectra as a function of time. The position of the burst on the sky can be determined to < {plus_minus}10{degrees} from the BATSE data stream. This position resolution is not sufficient to point a large, optical telescope at the exact position of a GRB which would determine its origin by associating it with a star. Because of their brief duration it is not known if GRBs are accompanied by visible radiation. Their seemingly large energy output suggests thatthis should be. Simply scaling the ratio of visible to gamma ray intensities of the Crab Nebula to the GRB output suggests that GRBs ought to be accompanied by visible flashes of magnitude 10 or so. A few photographs of areas containing a burst location that were coincidentally taken during the burst yield lower limits on visible output of magnitude 4. The detection of visible light during the GRB would provide information on burst physics, provide improved pointing coordinates for precise examination of the field by large telescope and provide the justification for larger dedicated optical counterpart instruments. The purpose of this experiment is to detect or set lower limits on optical counterpart radiation simultaneously accompanying the gamma rays from

  12. Probing the Isotropy in the Sky Distribution of the Gamma-Ray Bursts

    E-Print Network [OSTI]

    Meszaros, A; Balazs, L G; Horvath, I; Vavrek, R

    2015-01-01

    The statistical tests - done by the authors - are surveyed, which verify the null-hypothesis of the intrinsic randomness in the angular distribution of gamma-ray bursts collected at BATSE Catalog. The tests use the counts-in-cells method, an analysis of spherical harmonics, a test based on the two-point correlation function and a method based on multiscale methods. The tests suggest that the intermediate subclass of gamma-ray bursts are distributed anisotropically.

  13. Prompt gamma ray neutron activation analysis of cadmium in municipal solid waste 

    E-Print Network [OSTI]

    Dendahl, Katherine Hoge

    1991-01-01

    PROMPT GAMMA RAY NEUTRON ACTIVATION ANALYSIS OF CADMIUM IN MUNICIPAL SOLID WASTE A Thesis by KATHERINE HOGE DENDAHL Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 1991 Major Subject: Industrial Hygiene PROMPT GAMMA RAY NEUTRON ACTIVATION ANALYSIS OP CADMIUM IN MUNICIPAL SOLID WASTE A Thesis by KATHERINE HOGE DENDAHL Approved as to style and content by: Ric rd B. K nz (Chair...

  14. An All-Sky Search for Steady VHE Gamma-Ray Sources

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    1999-01-01

    The Milagrito water Cherenkov detector in the Jemez Mountains near Los Alamos, New Mexico took data from February 1997 to April 1998. Milagrito served as a prototype for the larger Milagro detector, which has just begun operations. Milagrito was the first large-aperture gamma-ray detector with sensitivity to gamma rays below 1 TeV. We report here on a search for steady emission from point sources over most of the northern sky using data from Milagrito.

  15. An All-Sky Search for Steady VHE Gamma-Ray Sources

    E-Print Network [OSTI]

    R. Atkins; W. Benbow; D. Berley; M. -L. Chen; D. G. Coyne; R. S. Delay; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; D. Evans; A. Falcone; L. Fleysher; R. Fleysher; G. Gisler; J. A. Goodman; T. J. Haines; C. M. Hoffman; S. Hugenberger; L. A. Kelley; I. Leonor; J. Macri; M. McConnell; J. F. McCullough; J. E. McEnery; R. S. Miller; A. I. Mincer; M. F. Morales; P. Nemethy; J. M. Ryan; M. Schneider; B. Shen; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; T. N. Thompson; O. T. Tumer; K. Wang; M. O. Wascko; S. Westerhoff; D. A. Williams; T. Yang; G. B. Yodh

    1999-06-23

    The Milagrito water Cherenkov detector in the Jemez Mountains near Los Alamos, New Mexico took data from February 1997 to April 1998. Milagrito served as a prototype for the larger Milagro detector, which has just begun operations. Milagrito was the first large-aperture gamma-ray detector with sensitivity to gamma rays below 1 TeV. We report here on a search for steady emission from point sources over most of the northern sky using data from Milagrito.

  16. Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample

    E-Print Network [OSTI]

    D. Rizzuto; C. Guidorzi; P. Romano; S. Covino; S. Campana; M. Capalbi; G. Chincarini; G. Cusumano; D. Fugazza; V. Mangano; A. Moretti; M. Perri; G. Tagliaferri

    2007-04-19

    We test the gamma-ray burst correlation between temporal variability and peak luminosity of the $\\gamma$-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (tested on low-luminosity GRBs. Our results show that these GRBs are definite outliers.

  17. HYPERACCRETING BLACK HOLE AS GAMMA-RAY BURST CENTRAL ENGINE. I. BARYON LOADING IN GAMMA-RAY BURST JETS

    SciTech Connect (OSTI)

    Lei Weihua; Zhang Bing; Liang Enwei E-mail: zhang@physics.unlv.edu

    2013-03-10

    A hyperaccreting stellar-mass black hole has been long speculated as the best candidate for the central engine of gamma-ray bursts (GRBs). Recent rich observations of GRBs by space missions such as Swift and Fermi pose new constraints on GRB central engine models. In this paper, we study the baryon-loading processes of a GRB jet launched from a black hole central engine. We consider a relativistic jet powered by {nu} {nu}-bar -annihilation or by the Blandford-Znajek (BZ) mechanism. We consider baryon loading from a neutrino-driven wind launched from a neutrino-cooling-dominated accretion flow. For a magnetically dominated BZ jet, we consider neutron drifting from the magnetic wall surrounding the jet and subsequent positron capture and proton-neutron inelastic collisions. The minimum baryon loads in both types of jet are calculated. We find that in both cases a more luminous jet tends to be more baryon poor. A neutrino-driven ''fireball'' is typically ''dirtier'' than a magnetically dominated jet, while a magnetically dominated jet can be much cleaner. Both models have the right scaling to interpret the empirical {Gamma}-L{sub iso} relation discovered recently. Since some neutrino-driven jets have too much baryon loading as compared with the data, we suggest that at least a good fraction of GRBs should have a magnetically dominated central engine.

  18. Andromeda: A mission to determine the gamma-ray burst distance scale F.A. Harrison, W.R. Cook, T.A. Prince, S.M. Schindler

    E-Print Network [OSTI]

    Prince, Thomas A.

    Andromeda: A mission to determine the gamma-ray burst distance scale F.A. Harrison, W.R. Cook, T was submitted to the STEDI program, and will also be proposed as a NASA Small Explorer. Keywords: bursts, gamma-rays, small missions 1 SCIENTIFIC OBJECTIVES 1.1 Gamma-ray Bursts Gamma-ray bursts GRBs were discovered

  19. ARE ABELL CLUSTERS CORRELATED WITH GAMMA-RAY BURSTS? Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450; khurley@sunspot.ssl.berkeley.edu

    E-Print Network [OSTI]

    California at Berkeley, University of

    ARE ABELL CLUSTERS CORRELATED WITH GAMMA-RAY BURSTS? K. HURLEY Space Sciences Laboratory statistical evidence that gamma-ray burst (GRB) sources are correlated with Abell clusters, based on analyses -- gamma rays: bursts 1. INTRODUCTION A correlation between the positions of gamma-ray bursts (GRBs

  20. Effects of Compton scattering on the Gamma Ray Spectra of Solar flares

    E-Print Network [OSTI]

    Jun'ichi Kotoku; Kazuo Makishima; Yukari Matsumoto; Mitsuhiro Kohama; Yukikatsu Terada; Toru Tamagawa

    2007-08-01

    Using fully relativistic GEANT4 simulation tool kit, the transport of energetic electrons generated in solar flares was Monte-Carlo simulated, and resultant bremsstrahlung gamma-ray spectra were calculated. The solar atmosphere was approximated by 10 vertically-stacked zones. The simulation took into account two important physical processes,that the bremsstrahlung photons emitted by precipitating relativistic electrons are strongly forward beamed toward the photosphere, and that the majority of these gamma-rays must be Compton back-scattered by the solar atmosphere in order to reach the observer. Then, the Compton degradation was found to make the observable gamma-ray spectra much softer than is predicted by simple analytic calculations. The gamma-ray signals were found to be enhanced by several conditions, including a broad pitch-angle distribution of the electrons, a near-limb flare longitude, and a significant tilt in the magnetic field lines if the flare longitude is rather small. These results successfully explain several important flare properties observed in the hard X-ray to gamma-ray range, including in particular those obtained with Yohkoh. A comparison of the Yohkoh spectrum from a GOES X3.7 class limb flare on 1998 November 22, with a simulation assuming a broad electron pitch-angle distribution, suggests that gamma-rays from this particular solar flare were a mixture of direct bremsstrahlung photons and their Comptonization.

  1. Spatial and Spectral Modeling of the Gamma-ray Distribution in the Large Magellanic Cloud

    E-Print Network [OSTI]

    Foreman, Gary; Gruendl, Robert; Hughes, Annie; Fields, Brian; Ricker, Paul

    2015-01-01

    We perform spatial and spectral analyses of the Large Magellanic Cloud (LMC) gamma-ray emission collected over 66 months by the Fermi Gamma-ray Space Telescope. In our spatial analysis, we model the LMC cosmic-ray distribution and gamma-ray production using observed maps of the LMC interstellar medium, star formation history, interstellar radiation field, and synchrotron emission. We use bootstrapping of the data to quantify the robustness of spatial model performance. We model the LMC gamma-ray spectrum using fitting functions derived from the physics of $\\pi^0$ decay, bremsstrahlung, and inverse Compton scattering. We find the integrated gamma-ray flux of the LMC from 200 MeV to 20 GeV to be $1.38 \\pm 0.02 \\times 10^{-7}$ ph cm$^{-2}$ s$^{-1}$, of which we attribute about 10% to inverse Compton scattering and 40% to bremsstrahlung. From our work, we conclude that the spectral index of the LMC cosmic-ray proton population is 2.4$\\pm$0.2, and we find that cosmic-ray energy loss through gamma-ray production is...

  2. Contribution of GRB Emission to the GeV Extragalactic Diffuse Gamma-Ray Flux

    E-Print Network [OSTI]

    S. Casanova; B. L. Dingus; Bing Zhang

    2006-11-03

    TeV gamma rays emitted by GRBs are converted into electron-positron pairs via interactions with the extragalactic infrared radiation fields. In turn the pairs produced, whose trajectories are randomized by magnetic fields, will inverse Compton scatter off the cosmic microwave background photons. The beamed TeV gamma ray flux from GRBs is thus transformed into a GeV isotropic gamma ray flux, which contributes to the total extragalactic gamma-ray background emission. Assuming a model for the extragalactic radiation fields, for the GRB redshift distribution and for the GRB luminosity function, we evaluate the contribution of the GRB prompt and scattered emissions to the measured extragalactic gamma-ray flux. To estimate this contribution we optimistically require that the energy flux at TeV energies is about 10 times stronger than the energy flux at MeV energies. The resulting gamma-ray diffuse background is only a small fraction of what is observed, allowing blazars and other sources to give the dominant contribution.

  3. Long lived central engines in Gamma Ray Bursts

    E-Print Network [OSTI]

    G. Ghisellini

    2008-10-01

    The central engine of Gamma Ray Bursts may live much longer than the duration of the prompt emission. Some evidence of it comes from the presence of strong precursors, post-cursors, and X-ray flares in a sizable fraction of bursts. Additional evidence comes from the fact that often the X-ray and the optical afterglow light curves do not track one another, suggesting that they are two different emission components. The typical "steep-flat-steep" behavior of the X-ray light curve can be explained if the same central engine responsible for the main prompt emission continues to be active for a long time, but with a decreasing power. The early X-ray "afterglow" emission is then the extension of the prompt emission, originating at approximately the same location, and is not due to forward shocks. If the bulk Lorentz factor Gamma is decreasing in time, the break ending the shallow phase can be explained, since at early times Gamma is large, and we see only a fraction of the emitting area. Later, when Gamma decreases, we see an increasing fraction of the emitting surface up to the time when Gamma ~ 1/theta_j. This time ends the shallow phase of the X-ray light curve. The origin of the late prompt emission can be the accretion of the fall-back material, with an accretion rate dot M proportional to t^(-5/3). The combination of this late prompt emission with the flux produced by the standard forward shock can explain the great diversity of the optical and the X-ray light curves.

  4. The first gamma-ray bursts in the universe

    SciTech Connect (OSTI)

    Mesler, R. A.; Pihlström, Y. M. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States); Whalen, Daniel J.; Smidt, Joseph [T-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Fryer, Chris L.; Lloyd-Ronning, N. M. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2014-05-20

    Gamma-ray bursts (GRBs) are the ultimate cosmic lighthouses, capable of illuminating the universe at its earliest epochs. Could such events probe the properties of the first stars at z ? 20, the end of the cosmic Dark Ages? Previous studies of Population III (Pop III) GRBs only considered explosions in the diffuse relic H II regions of their progenitors or bursts that are far more energetic than those observed to date. However, the processes that produce GRBs at the highest redshifts likely reset their local environments, creating much more complicated structures than those in which relativistic jets have been modeled so far. These structures can greatly affect the luminosity of the afterglow and hence the redshift at which it can be detected. We have now simulated Pop III GRB afterglows in H II regions, winds, and dense shells ejected by the star during the processes that produce the burst. We find that GRBs with E {sub iso,?} = 10{sup 51}-10{sup 53} erg will be visible at z ? 20 to the next generation of near infrared and radio observatories. In many cases, the environment of the burst, and hence progenitor type, can be inferred from the afterglow light curve. Although some Pop III GRBs are visible to Swift and the Very Large Array now, the optimal strategy for their detection will be future missions like the proposed EXIST and JANUS missions with large survey areas and onboard X-ray and infrared telescopes that can track their near-infrared flux from the moment of the burst, thereby identifying their redshifts.

  5. COMPACT BINARY PROGENITORS OF SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Giacomazzo, Bruno [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309 (United States); Perna, Rosalba [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Rezzolla, Luciano [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Potsdam D-14476 (Germany); Troja, Eleonora [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lazzati, Davide [Department of Physics, NC State University, 2401 Stinson Drive, Raleigh, NC 27695-8202 (United States)

    2013-01-10

    In recent years, detailed observations and accurate numerical simulations have provided support to the idea that mergers of compact binaries containing either two neutron stars (NSs) or an NS and a black hole (BH) may constitute the central engine of short gamma-ray bursts (SGRBs). The merger of such compact binaries is expected to lead to the production of a spinning BH surrounded by an accreting torus. Several mechanisms can extract energy from this system and power the SGRBs. Here we connect observations and numerical simulations of compact binary mergers, and use the current sample of SGRBs with measured energies to constrain the mass of their powering tori. By comparing the masses of the tori with the results of fully general-relativistic simulations, we are able to infer the properties of the binary progenitors that yield SGRBs. By assuming a constant efficiency in converting torus mass into jet energy, {epsilon}{sub jet} = 10%, we find that most of the tori have masses smaller than 0.01 M{sub Sun }, favoring 'high-mass' binary NSs mergers, i.e., binaries with total masses {approx}> 1.5 the maximum mass of an isolated NS. This has important consequences for the gravitational wave signals that may be detected in association with SGRBs, since 'high-mass' systems do not form a long-lived hypermassive NS after the merger. While NS-BH systems cannot be excluded to be the engine of at least some of the SGRBs, the BH would need to have an initial spin of {approx}0.9 or higher.

  6. Quark deconfinement and the duration of short Gamma Ray Bursts

    E-Print Network [OSTI]

    Alessandro Drago; Andrea Lavagno; Brian Metzger; Giuseppe Pagliara

    2015-10-19

    We propose a model for short duration gamma-ray bursts (sGRBs) based on the formation of a quark star after the merger of two neutron stars. We assume that the sGRB central engine is a proto-magnetar, which has been previously invoked to explain the plateau-like X-ray emission observed following both long and short GRBs. Here, we show that: i) a few milliseconds after the merger it is possible to form a stable and massive star made in part of quarks; ii) during the early cooling phase of the incompletely formed quark star, the flux of baryons ablated from the surface by neutrinos is large and it does not allow the outflow to achieve a bulk Lorentz factor high enough to produce a GRB; iii) after the quark burning front reaches the stellar surface, baryon ablation ceases and the jet becomes too baryon poor to produce a GRB; iv) however, between these two phases a GRB can be produced over the finite timescale required for the baryon pollution to cease; a characteristic timescale of the order of $\\sim 0.1 $ s naturally results from the time the conversion front needs to cover the distance between the rotational pole and the latitude of the last closed magnetic field line; v) we predict a correlation between the luminosity of the sGRB and its duration, consistent with the data; vi) our model also predicts a delay of the order of ten seconds between the time of the merger event and the sGRB, allowing for the possibility of precursor emission and implying that the jet will encounter the dense cocoon formed immediately after the merger.

  7. A Search for Prompt Very High Energy Emission from Satellite-detected Gamma-ray Bursts using Milagro

    E-Print Network [OSTI]

    Parkinson, P M Saz

    2007-01-01

    Gamma-ray bursts (GRBs) have been detected up to GeV energies and are predicted by many models to emit in the very high energy (VHE, > 100 GeV) regime too. Detection of such emission would allow us to constrain GRB models. Since its launch, in late 2004, the Swift satellite has been locating GRBs at a rate of approximately 100 per year. The rapid localization and follow-up in many wavelengths has revealed new and unexpected phenomena, such as delayed emission in the form of bright X-ray flares. The Milagro gamma-ray observatory is a wide field of view (2 sr) instrument employing a water Cherenkov detector to continuously ($>$ 90% duty cycle) observe the overhead sky in the 100 GeV to 100 TeV energy range. Over 100 GRBs are known to have been in the field of view of Milagro since January 2000, including 57 since the launch of Swift (through May 2007). We discuss the results of the searches for prompt emission from these bursts, as well as for delayed emission from the X-ray flares observed in some of the Swift...

  8. A Search for Prompt Very High Energy Emission from Satellite-detected Gamma-ray Bursts using Milagro

    E-Print Network [OSTI]

    Milagro Collaboration; P. M. Saz Parkinson; B. L. Dingus

    2007-10-11

    Gamma-ray bursts (GRBs) have been detected up to GeV energies and are predicted by many models to emit in the very high energy (VHE, > 100 GeV) regime too. Detection of such emission would allow us to constrain GRB models. Since its launch, in late 2004, the Swift satellite has been locating GRBs at a rate of approximately 100 per year. The rapid localization and follow-up in many wavelengths has revealed new and unexpected phenomena, such as delayed emission in the form of bright X-ray flares. The Milagro gamma-ray observatory is a wide field of view (2 sr) instrument employing a water Cherenkov detector to continuously ($>$ 90% duty cycle) observe the overhead sky in the 100 GeV to 100 TeV energy range. Over 100 GRBs are known to have been in the field of view of Milagro since January 2000, including 57 since the launch of Swift (through May 2007). We discuss the results of the searches for prompt emission from these bursts, as well as for delayed emission from the X-ray flares observed in some of the Swift bursts.

  9. Identification of a New $\\gamma$-ray-emitting narrow-line Seyfert 1 Galaxy, at Redshift $\\sim1$

    E-Print Network [OSTI]

    Yao, Su; Zhou, Hongyan; Komossa, S; Zhang, Jin; Qiao, Erlin; Liu, Bifang

    2015-01-01

    We report on the identification of a new $\\gamma$-ray-emitting narrow-line Seyfert 1 (NLS1) galaxy, SDSS J122222.55+041315.7, which increases the number of known objects of this remarkable but rare type of active galactic nuclei (AGN) to seven. Its optical spectrum, obtained in the Sloan Digital Sky Survey-Baryon Oscillation Spectroscopic Survey, reveals a broad H $\\beta$ emission line with a width (FWHM) of 1734$\\pm$104 km s$^{-1}$. This, along with strong optical Fe II multiplets [$R_{4570}=0.9$] and a weak [O III] $\\lambda 5007$ emission line, makes the object a typical NLS1. On the other hand, the source exhibits a high radio brightness temperature, rapid infrared variability, and a flat X-ray spectrum extending up to $\\sim$200 keV. It is associated with a luminous $\\gamma$-ray source detected significantly with {\\it Fermi}/LAT. Correlated variability with other wavebands has not yet been tested. The spectral energy distribution can be well modelled by a one-zone leptonic jet model. This new member is by ...

  10. Short gamma-ray bursts from binary neutron star mergers: the time-reversal scenario

    E-Print Network [OSTI]

    Ciolfi, Riccardo

    2015-01-01

    After decades of observations the physical mechanisms that generate short gamma-ray bursts (SGRBs) still remain unclear. Observational evidence provides support to the idea that SGRBs originate from the merger of compact binaries, consisting of two neutron stars (NSs) or a NS and a black hole (BH). Theoretical models and numerical simulations seem to converge to an explanation in which the central engine of SGRBs is given by a spinning BH surrounded by a hot accretion torus. Such a BH-torus system can be formed in compact binary mergers and is able to launch a relativistic jet, which can then produce the SGRB. This basic scenario, however, has recently been challenged by Swift satellite observations, which have revealed long-lasting X-ray afterglows in association with a large fraction of SGRB events. The long durations of these afterglows (from minutes to several hours) cannot be explained by the $\\sim\\text{s}$ accretion timescale of the torus onto the BH, and, instead, suggest a long-lived NS as the persist...

  11. ON THE ORIGIN OF > 10 GeV PHOTONS IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect (OSTI)

    Wang Xiangyu; Liu Ruoyu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Lemoine, Martin [Institut d'Astrophysique de paris, CNRS, UPMC, 98 bis boulevard Arago, F-75014 Paris (France)

    2013-07-10

    Fermi/LAT has detected long-lasting high-energy photons (>100 MeV) from gamma-ray bursts (GRBs), with the highest energy photons reaching about 100 GeV. One proposed scenario is that they are produced by high-energy electrons accelerated in GRB forward shocks via synchrotron radiation. We study the maximum synchrotron photon energy in this scenario, considering the properties of the microturbulence magnetic fields behind the shock, as revealed by recent particle-in-cell simulations and theoretical analyses of relativistic collisionless shocks. Due to the small-scale nature of the microturbulent magnetic field, the Bohm acceleration approximation, in which the scattering mean free path is equal to the particle Larmor radius, breaks down at such high energies. This effect leads to a typical maximum synchrotron photon of a few GeV at 100 s after the burst and this maximum synchrotron photon energy decreases quickly with time. We show that the fast decrease of the maximum synchrotron photon energy leads to a fast decay of the synchrotron flux. The 10-100 GeV photons detected after the prompt phase cannot be produced by the synchrotron mechanism. They could originate from the synchrotron self-Compton emission of the early afterglow if the circumburst density is sufficiently large, or from the external inverse Compton process in the presence of central X-ray emission, such as X-ray flares and prompt high-latitude X-ray emission.

  12. NO FLARES FROM GAMMA-RAY BURST AFTERGLOW BLAST WAVES ENCOUNTERING SUDDEN CIRCUMBURST DENSITY CHANGE

    SciTech Connect (OSTI)

    Gat, Ilana; Van Eerten, Hendrik; MacFadyen, Andrew [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States)

    2013-08-10

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

  13. Study of possible systematics in the L*X - Ta* correlation of Gamma Ray Bursts

    E-Print Network [OSTI]

    M. G. Dainotti; V. F. Cardone; S. Capozziello; M. Ostrowski; R. Willingale

    2011-01-09

    Gamma Ray Bursts (GRBs) are the most energetic sources in the universe and among the farthest known astrophysical sources. These features make them appealing candidates as standard candles for cosmological applications so that studying the physical mechanisms for the origin of the emission and correlations among their observable properties is an interesting task. We consider here the luminosity L*X - break time Ta* (hereafter LT) correlation and investigate whether there are systematics induced by selection effects or redshift dependent calibra- tion. We perform this analysis both for the full sample of 77 GRBs with known redshift and for the subsample of GRBs having canonical X-ray light curves, hereafter called U0095 sample. We do not find any systematic bias thus con- firming the existence of physical GRB subclasses revealed by tight correlations of their afterglow properties. Furthermore, we study the possibility of applying the LT correlation as a redshift estimator both for the full distribution and for the canonical lightcurves. The large uncertainties and the non negligible intrin- sic scatter make the results not so encouraging, but there are nevertheless some hints motivating a further analysis with an increased U0095 sample.

  14. Duration distributions for different softness groups of gamma-ray bursts

    E-Print Network [OSTI]

    Y. -P. Qin; A. C. Gupta; J. H. Fan; C. -Y. Su; R. -J. Lu

    2010-10-10

    Gamma-ray bursts (GRBs) are divided into two classes according to their durations. We investigate if the softness of bursts plays a role in the conventional classification of the objects. We employ the BATSE (Burst and Transient Source Experiment) catalog and analyze the duration distributions of different groups of GRBs associated with distinct softness. Our analysis reveals that the conventional classification of GRBs with the duration of bursts is influenced by the softness of the objects. There exits a bimodality in the duration distribution of GRBs for each group of bursts and the time position of the dip in the bimodality histogram shifts with the softness parameter. Our findings suggest that the conventional classification scheme should be modified by separating the two well-known populations in different softness groups, which would be more reasonable than doing so with a single sample. According to the relation between the dip position and the softness parameter, we get an empirical function that can roughly set apart the short-hard and long-soft bursts: $SP = (0.100 \\pm 0.028) T_{90}^{-(0.85 \\pm 0.18)}$, where $SP$ is the softness parameter adopted in this paper.

  15. Short gamma-ray bursts from binary neutron star mergers: the time-reversal scenario

    E-Print Network [OSTI]

    Riccardo Ciolfi; Daniel M. Siegel

    2015-05-06

    After decades of observations the physical mechanisms that generate short gamma-ray bursts (SGRBs) still remain unclear. Observational evidence provides support to the idea that SGRBs originate from the merger of compact binaries, consisting of two neutron stars (NSs) or a NS and a black hole (BH). Theoretical models and numerical simulations seem to converge to an explanation in which the central engine of SGRBs is given by a spinning BH surrounded by a hot accretion torus. Such a BH-torus system can be formed in compact binary mergers and is able to launch a relativistic jet, which can then produce the SGRB. This basic scenario, however, has recently been challenged by Swift satellite observations, which have revealed long-lasting X-ray afterglows in association with a large fraction of SGRB events. The long durations of these afterglows (from minutes to several hours) cannot be explained by the $\\sim\\text{s}$ accretion timescale of the torus onto the BH, and, instead, suggest a long-lived NS as the persistent source of radiation. Yet, if the merger results in a massive NS the conditions to generate a relativistic jet and thus the prompt SGRB emission are hardly met. Here we consider an alternative scenario that can reconcile the two aspects and account for both the prompt and the X-ray afterglow emission. Implications for future observations, multi-messenger astronomy and for constraining NS properties are discussed, as well as potential challenges for the model.

  16. Implications of plasma beam instabilities for the statistics of the Fermi hard gamma-ray blazars and the origin of the extragalactic gamma-ray background

    SciTech Connect (OSTI)

    Broderick, Avery E. [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON N2L 2Y5 (Canada); Pfrommer, Christoph; Puchwein, Ewald [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Chang, Philip [Department of Physics, University of Wisconsin-Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States)

    2014-08-01

    Fermi has been instrumental in constraining the luminosity function and redshift evolution of gamma-ray bright BL Lac objects, a subpopulation of blazars with almost featureless optical spectra. This includes limits on the spectrum and anisotropy of the extragalactic gamma-ray background (EGRB), redshift distribution of nearby Fermi active galactic nuclei (AGNs), and the construction of a logN-log S relation. Based on these, it has been argued that the evolution of the gamma-ray bright BL Lac population must be much less dramatic than that of other AGNs. However, critical to such claims is the assumption that inverse Compton cascades reprocess emission above a TeV into the Fermi energy range, substantially enhancing the strength of the observed limits. Here we demonstrate that in the absence of such a process, due, e.g., to the presence of virulent plasma beam instabilities that preempt the cascade, a population of TeV-bright BL Lac objects that evolve similarly to quasars is consistent with the population of hard gamma-ray BL Lac objects observed by Fermi. Specifically, we show that a simple model for the properties and luminosity function is simultaneously able to reproduce their logN-log S relation, local redshift distribution, and contribution to the EGRB and its anisotropy without any free parameters. Insofar as the naturalness of a picture in which the hard gamma-ray BL Lac population exhibits the strong redshift evolution observed in other tracers of the cosmological history of accretion onto halos is desirable, this lends support for the absence of the inverse Compton cascades and the existence of the beam plasma instabilities.

  17. Demystifying an unidentified EGRET source by VHE gamma-ray observations

    E-Print Network [OSTI]

    Olaf Reimer; Stefan Funk

    2006-11-22

    In a novel approach in observational high-energy gamma-ray astronomy, observations carried out by imaging atmospheric Cherenkov telescopes provide necessary templates to pinpoint the nature of intriguing, yet unidentified EGRET gamma-ray sources. Using GeV-photons detected by CGRO EGRET and taking advantage of high spatial resolution images from H.E.S.S. observations, we were able to shed new light on the EGRET observed gamma-ray emission in the Kookaburra complex, whose previous coverage in the literature is somewhat contradictory. 3EGJ1420-6038 very likely accounts for two GeV gamma-ray sources (E>1 GeV), both in positional coincidence with the recently reported pulsar wind nebulae (PWN) by HESS in the Kookaburra/Rabbit complex. PWN associations at VHE energies, supported by accumulating evidence from observations in the radio and X-ray band, are indicative for the PSR/plerionic origin of spatially coincident, but still unidentified Galactic gamma-ray sources from EGRET. This not only supports the already suggested connection between variable, but unidentified low-latitude gamma-ray sources with pulsar wind nebulae (3EGJ1420-6038 has been suggested as PWN candidate previoulsy), it also documents the ability of resolving apparently confused EGRET sources by connecting the GeV emission as measured from a large-aperture space-based gamma-ray instrument with narrow field-of-view but superior spatial resolution observations by ground-based atmospheric Cherenkov telescopes, a very promising identification technique for achieving convincing individual source identifications in the era of GLAST-LAT.

  18. GRB 090727 AND GAMMA-RAY BURSTS WITH EARLY-TIME OPTICAL EMISSION

    SciTech Connect (OSTI)

    Kopac, D.; Gomboc, A.; Japelj, J. [Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana (Slovenia); Kobayashi, S.; Mundell, C. G.; Bersier, D.; Cano, Z.; Smith, R. J.; Steele, I. A.; Virgili, F. J. [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, CH41 1LD (United Kingdom); Guidorzi, C. [Physics Departments, University of Ferrara, via Saragat 1, I-44122, Ferrara (Italy); Melandri, A., E-mail: drejc.kopac@fmf.uni-lj.si [INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy)

    2013-07-20

    We present a multi-wavelength analysis of Swift gamma-ray burst GRB 090727, for which optical emission was detected during the prompt gamma-ray emission by the 2 m autonomous robotic Liverpool Telescope and subsequently monitored for a further two days with the Liverpool and Faulkes Telescopes. Within the context of the standard fireball model, we rule out a reverse shock origin for the early-time optical emission in GRB 090727 and instead conclude that the early-time optical flash likely corresponds to emission from an internal dissipation process. Putting GRB 090727 into a broader observational and theoretical context, we build a sample of 36 gamma-ray bursts (GRBs) with contemporaneous early-time optical and gamma-ray detections. From these GRBs, we extract a sub-sample of 18 GRBs, which show optical peaks during prompt gamma-ray emission, and perform detailed temporal and spectral analysis in gamma-ray, X-ray, and optical bands. We find that in most cases early-time optical emission shows sharp and steep behavior, and notice a rich diversity of spectral properties. Using a simple internal shock dissipation model, we show that the emission during prompt GRB phase can occur at very different frequencies via synchrotron radiation. Based on the results obtained from observations and simulation, we conclude that the standard external shock interpretation for early-time optical emission is disfavored in most cases due to sharp peaks ({Delta}t/t < 1) and steep rise/decay indices, and that internal dissipation can explain the properties of GRBs with optical peaks during gamma-ray emission.

  19. ILLUMINATING THE DARKEST GAMMA-RAY BURSTS WITH RADIO OBSERVATIONS

    SciTech Connect (OSTI)

    Zauderer, B. A.; Berger, E.; Margutti, R.; Fong, W.; Laskar, T.; Chornock, R.; Soderberg, A. M. [Department of Astronomy, Harvard University, Cambridge, MA 02138 (United States); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Olivares E, F.; Greiner, J. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Perley, D. A.; Horesh, A.; Carpenter, J. [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91225 (United States); Updike, A. C. [Department of Chemistry and Physics, Roger Williams University, Bristol, RI 02809 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Menten, K. M. [Max-Planck-Institut fuer Radioastronomie, D-53121 Bonn (Germany); Nakar, E. [Department of Astrophysics, Sackler School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Chandra, P. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Ganeshkhind, Pune 411007 (India); Castro-Tirado, A. J. [Instituto de Astrofisica de Andalucia (IAA-CSIC), P.O. Box 03004, E-18080 Granada (Spain); Bremer, M. [Institut de Radioastronomie Millimetrique, 300 rue de la Piscine, F-38406 Saint Martin d'Heres (France); and others

    2013-04-20

    We present X-ray, optical, near-infrared (IR), and radio observations of gamma-ray bursts (GRBs) 110709B and 111215A, as well as optical and near-IR observations of their host galaxies. The combination of X-ray detections and deep optical/near-IR limits establish both bursts as ''dark''. Sub-arcsecond positions enabled by radio detections lead to robust host galaxy associations, with optical detections that indicate z {approx}< 4 (110709B) and z Almost-Equal-To 1.8-2.9 (111215A). We therefore conclude that both bursts are dark due to substantial rest-frame extinction. Using the radio and X-ray data for each burst we find that GRB 110709B requires A{sub V}{sup host}{approx}>5.3 mag and GRB 111215A requires A{sub V}{sup host}{approx}>8.5 mag (assuming z = 2). These are among the largest extinction values inferred for dark bursts to date. The two bursts also exhibit large neutral hydrogen column densities of N{sub H,{sub int}} {approx}> 10{sup 22} cm{sup -2} (z = 2) as inferred from their X-ray spectra, in agreement with the trend for dark GRBs. Moreover, the inferred values are in agreement with the Galactic A{sub V} -N{sub H} relation, unlike the bulk of the GRB population. Finally, we find that for both bursts the afterglow emission is best explained by a collimated outflow with a total beaming-corrected energy of E{sub {gamma}} + E{sub K} Almost-Equal-To (7-9) Multiplication-Sign 10{sup 51} erg (z = 2) expanding into a wind medium with a high density, M Almost-Equal-To (6-20) Multiplication-Sign 10{sup -5} M{sub Sun} yr{sup -1} (n Almost-Equal-To 100-350 cm{sup -3} at Almost-Equal-To 10{sup 17} cm). While the energy release is typical of long GRBs, the inferred density may be indicative of larger mass-loss rates for GRB progenitors in dusty (and hence metal rich) environments. This study establishes the critical role of radio observations in demonstrating the origin and properties of dark GRBs. Observations with the JVLA and ALMA will provide a sample with sub-arcsecond positions and robust host associations that will help to shed light on obscured star formation and the role of metallicity in GRB progenitors.

  20. Sustainability of gamma-ray isotopics evaluation codes

    SciTech Connect (OSTI)

    Vo, Duc [Los Alamos National Laboratory; Koskelo, Markku [AQUILA TECHNOLOGIES; Mcginnis, Brent [ORNL; Wang, Tzu - Feng [LLNL; Peerani, Paolo [IPSC, ISPRA, ITALY; Renha, Geraldo [ABACC, BRAZIL; Dias, Fabio C [NECB, BRAZIL

    2010-01-01

    In November 2005, the international workshop 'Gamma Evaluation Codes for Plutonium and Uranium Isotope Abundance Measurements by High-Resolution Gamma Spectrometry: Current Status and Future Challenges' was held in Karlsruhe, Germany. Some of the main issues discussed during the November 2005 meeting were related to concerns voiced by international inspectorate authorities such as the International Atomic Energy Agency (IAEA), the European Atomic Energy Community (EURATOM), and the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC) about the standardization and sustainability of gamma-ray isotopic analysis codes that are commonly used during safeguards inspections. A follow-up international workshop was conducted in Oak Ridge, TN in 2008. This workshop was in response to needs expressed by the international safeguards community during the Karlsruhe meeting and recommendations made under Action Sheet 14; a cooperative effort between the U. S. Department of Energy and ABACC. The purpose of the Oak Ridge workshop was to bring code developers and end users together to better understand the capabilities and limitations of the codes; to discuss mechanisms to ensure these codes are sustained and quality tested; and to ensure updates or revisions are performed in a controlled manner. During an Action Sheet 14 meeting held in Rio de Janeiro, Brazil in which the IAEA and EURATOM participated as observers, and in subsequent meetings of the European Safeguards Research and Development Association (ESARDA), all parties agreed that the regional working group initially established under the DOE/ABACC cooperation should be expanded to an international working group. The purpose of the international working group is to provide a forum to exchange information, discuss technical developments, and validate and test the various codes. However, progress to formally establish the working has been slowed by a lack of dedicated funding and competing priorities within the various international organizations. Recently, the ESARDA Nondestructive Assay Working Group established a dedicated website for the International Working Group on Gamma Spectrometry Techniques (1 WG-GST). In this paper, we will explore specific steps that should be taken to strengthen this working group's ability to affect development of a common testing platform and address concerns regarding applicability, sustainability and version control for these important codes.

  1. DIVERSITY OF SHORT GAMMA-RAY BURST AFTERGLOWS FROM COMPACT BINARY MERGERS HOSTING PULSARS

    SciTech Connect (OSTI)

    Holcomb, Cole; Ramirez-Ruiz, Enrico; De Colle, Fabio; Montes, Gabriela [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2014-07-20

    Short-duration gamma-ray bursts (sGRBs) are widely believed to result from the mergers of compact binaries. This model predicts an afterglow that bears the characteristic signatures of a constant, low-density medium, including a smooth prompt-afterglow transition, and a simple temporal evolution. However, these expectations are in conflict with observations for a non-negligible fraction of sGRB afterglows. In particular, the onset of the afterglow phase for some of these events appears to be delayed and, in addition, a few of them exhibit late-time rapid fading in their light curves. We show that these peculiar observations can be explained independently of ongoing central engine activity if some sGRB progenitors are compact binaries hosting at least one pulsar. The Poynting flux emanating from the pulsar companion can excavate a bow-shock cavity surrounding the binary. If this cavity is larger than the shock deceleration length scale in the undisturbed interstellar medium, then the onset of the afterglow will be delayed. Should the deceleration occur entirely within the swept-up thin shell, a rapid fade in the light curve will ensue. We identify two types of pulsar that can achieve the conditions necessary for altering the afterglow: low-field, long-lived pulsars, and high-field pulsars. We find that a sizable fraction (?20%-50%) of low-field pulsars are likely to reside in neutron star binaries based on observations, while their high-field counterparts are not. Hydrodynamical calculations motivated by this model are shown to be in good agreement with observations of sGRB afterglow light curves.

  2. Constraints on GRB TeV Emission from the GeV Extragalactic Diffuse Gamma-Ray Flux

    E-Print Network [OSTI]

    Casanova, S; Zhang, B; Zhang, Bing

    2006-01-01

    TeV gamma rays emitted by GRBs are converted into electron-positron pairs via interactions with the extragalactic infrared radiation fields. In turn the pairs produced, whose trajectories are randomized by magnetic fields, will inverse Compton scatter off the cosmic microwave background photons. The beamed TeV gamma ray flux from GRBs is thus transformed into a GeV isotropic gamma ray flux, which contributes to the total extragalactic gamma-ray background emission. Assuming a model for the extragalactic radiation fields, for the GRB redshift distribution and for the GRB luminosity function, we use the measured GeV extragalactic gamma-ray flux to set upper limits on the GRB emission in TeV gamma rays that is predicted in several models.

  3. Operation Greenhouse. Scientific Director's report of atomic-weapon tests at Eniwetok, 1951. Annex 1. 2. Delayed gamma-ray measurements. Part 1. Gamma-ray spectrum measurements (abridged)

    SciTech Connect (OSTI)

    Gibson, H.F.; Miller; Motz, J.W.; Smeltzer, J.C.; Wyckoff, H.O.

    1985-09-01

    Measurements of bomb efficiencies from the number of gamma rays requires fundamentally two separate experiments. The average number of gamma rays emitted from the fission fragments (delayed gamma rays) per fission must be determined. This experiment can be carried out in the laboratory. A second experiment, the absolute determination of the number of gamma rays from the bomb was also attempted. Because gamma rays are not directly observable but are measurable only through their secondary effects, and because the probability of occurrence of the secondary effects depends upon the gamma ray energy, it is not usually possible to count directly the number of gamma rays in a heterochromatic spectrum. A spectral distribution must be first obtained from which the actual total number of gamma rays may be computed. This volume discusses, in detail, the planning for the experiment and the spectral distribution of collimated gamma-rays determined from the Greenhouse tests on two shots. A discussion of measurement of build-up factor which is needed to estimate the effect of collimation is also given.

  4. Probing the gamma-ray emission from HESS J1834-087 using H.E.S.S. and Fermi LAT observations

    E-Print Network [OSTI]

    :,; Aharonian, F; Benkhali, F Ait; Akhperjanian, A G; Angüner, E; Anton, G; Backes, M; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Tjus, J Becker; Bernlöhr, K; Birsin, E; Bissaldi, E; Biteau, J; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Chadwick, P M; Chalme-Calvet, R; Chaves, R C G; Cheesebrough, A; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Cui, Y; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataď, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Giavitto, G; Giebels, B; Glicenstein, J F; Grondin, M -H; Grudzi?ska, M; Häffner, S; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzy?ski, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Klu?niak, W; Kneiske, T; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lemičre, A; Lemoine-Goumard, M; Lenain, J -P; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Marx, R; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Méhault, J; Meintjes, P J; Menzler, U; Meyer, M; Moderski, R; Mohamed, M; Moulin, E; Murach, T; Naumann, C L; de Naurois, M; Niemiec, J; Nolan, S J; Oakes, L; Odaka, H; Ohm, S; Wilhelmi, E de Ońa; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Raue, M; Reichardt, I; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Romoli, C; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spengler, G; Spies, F; Stawarz, ?; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Tavernet, J -P; Tavernier, T; Taylor, A M; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; van Soelen, B; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorster, M; Vuillaume, T; Wagner, S J; Wagner, P; Wagner, R M; Ward, M; Weidinger, M; Weitzel, Q; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Yang, R; Zabalza, V; Zacharias, M; Zdziarski, A A; Zech, A; Zechlin, H -S; Acero, F; Casandjian, J M; Cohen-Tanugi, J; Giordano, F; Guillemot, L; Lande, J; Pletsch, H; Uchiyama, Y

    2014-01-01

    Previous observations with HESS have revealed the existence of an extended very-high-energy (VHE; E>100 GeV) gamma-ray source, HESS J1834-087, coincident with the SNR W41. The origin of the gamma-ray emission has been further investigated with HESS and the Fermi-LAT. The gamma-ray data provided by 61h (HESS) and 4 yrs (Fermi LAT) of observations cover over 5 decades in energy (1.8GeV - 30TeV). The morphology and spectrum of the TeV and GeV sources have been studied and multi-wavelength data have been used to investigate the origin of the observed emission. The TeV source can be modeled with a sum of two components: one point-like and one significantly extended (sig_TeV = 0.17{\\deg}), both centered on SNR W41 and exhibiting spectra described by a power law of index 2.6. The GeV source detected with Fermi is extended (sig_GeV =0.15{\\deg}) and morphologically matches the VHE emission. Its spectrum can be described by a power-law with index 2.15 and joins smoothly the one of the whole TeV source. A break appears ...

  5. Study of Gamma-Ray Bursts of energy E 10 GeV with the ARGO-YBJ detector

    E-Print Network [OSTI]

    Morselli, Aldo

    Study of Gamma-Ray Bursts of energy E 10 GeV with the ARGO-YBJ detector ARGO-YBJ Collaboration of high energy gamma-ray bursts can be performed by large area air shower arrays operating at very high is the study of gamma-ray bursts of energies E 10 GeV. This can be achieved using the "single particle

  6. The cosmic gamma-ray background in the MeV range

    E-Print Network [OSTI]

    P. Ruiz-Lapuente; M. Casse; E. Vangioni-Flam

    2000-09-20

    The $\\gamma$-ray background from supernovae is calculated on the basis of the reconstructed efficiency of supernova explosions from star formation at various redshifts. The calculations presented here show how Type Ia SN rates compatible with the results of optical supernova searches give a background emission in the MeV range that can explain the extragalactic emission measured by COMPTEL and SMM. Star formation histories reaching maximum values of 0.3-0.4 M$_{\\odot}$ yr$^{-1}$ Mpc$^{-3}$ at z$\\sim$ 1.5 (and/or possibly keeping that value to higher z) give a $\\gamma$-ray background compatible with observations while they also predict the observed supernova rates per comoving volume. The $\\gamma$-ray background in the MeV range is mostly sensitive to the star formation rate at z$\\sim$ 1-2, but the activity in forming stars at even higher z has an influence as well on the absolute level of the cosmic $\\gamma$-ray background: the time elapsed by the SNe Ia progenitors until they explode has a broad distribution and the rates of SNe Ia at z$\\sim$ 1.5-2 depend on the formation frequencies of their progenitor stars at earlier epochs. The mutual consistency of predictions of optical rates and integrated emission in the $\\gamma$-ray domain place in a firm ground the Type Ia supernova identification as the astrophysical source responsible for this cosmic background

  7. Evidence of cross-correlation between the CMB lensing and the gamma-ray sky

    E-Print Network [OSTI]

    N. Fornengo; L. Perotto; M. Regis; S. Camera

    2015-03-02

    We report the measurement of the angular power spectrum of cross-correlation between the unresolved component of the Fermi-LAT gamma-ray sky-maps and the CMB lensing potential map reconstructed by the Planck satellite. The matter distribution in the Universe determines the bending of light coming from the last scattering surface. At the same time, the matter density drives the growth history of astrophysical objects, including their capability at generating non-thermal phenomena, which in turn give rise to gamma-ray emissions. The Planck lensing map provides information on the integrated distribution of matter, while the integrated history of gamma-ray emitters is imprinted in the Fermi-LAT sky maps. We report here the first evidence of their correlation. We find that the multipole dependence of the cross-correlation measurement is in agreement with current models of the gamma-ray luminosity function for AGN and star forming galaxies, with a statistical evidence of 3.0$\\sigma$. Moreover, its amplitude can in general be matched only assuming that these extra-galactic emitters are also the bulk contribution of the measured isotopic gamma-ray background (IGRB) intensity. This leaves little room for a big contribution from galactic sources to the IGRB measured by Fermi-LAT, pointing toward a direct evidence of the extragalactic origin of the IGRB.

  8. Demystifying an unidentified EGRET source by VHE gamma-ray observations

    E-Print Network [OSTI]

    Reimer, O; Reimer, Olaf; Funk, Stefan

    2006-01-01

    In a novel approach in observational high-energy gamma-ray astronomy, observations carried out by imaging atmospheric Cherenkov telescopes provide necessary templates to pinpoint the nature of intriguing, yet unidentified EGRET gamma-ray sources. Using GeV-photons detected by CGRO EGRET and taking advantage of high spatial resolution images from H.E.S.S. observations, we were able to shed new light on the EGRET observed gamma-ray emission in the Kookaburra complex, whose previous coverage in the literature is somewhat contradictory. 3EGJ1420-6038 very likely accounts for two GeV gamma-ray sources (E>1 GeV), both in positional coincidence with the recently reported pulsar wind nebulae (PWN) by HESS in the Kookaburra/Rabbit complex. PWN associations at VHE energies, supported by accumulating evidence from observations in the radio and X-ray band, are indicative for the PSR/plerionic origin of spatially coincident, but still unidentified Galactic gamma-ray sources from EGRET. This not only supports the already s...

  9. Discrimination of gamma rays due to inelastic neutron scattering in AGATA

    E-Print Network [OSTI]

    A. Ataç; A. Ka?ka?; S. Akkoyun; M. ?enyi?it; T. Hüyük; S. O. Kara; J. Nyberg

    2009-06-10

    Possibilities of discriminating neutrons and gamma rays in the AGATA gamma-ray tracking spectrometer have been investigated with the aim of reducing the background due to inelastic scattering of neutrons in the high-purity germanium crystals. This background may become a serious problem especially in experiments with neutron-rich radioactive ion beams. Simulations using the Geant4 toolkit and a tracking program based on the forward tracking algorithm were carried out by emitting neutrons and gamma rays from the center of AGATA. Three different methods were developed and tested in order to find 'fingerprints' of the neutron interaction points in the detectors. In a simulation with simultaneous emission of six neutrons with energies in the range 1-5 MeV and ten gamma rays with energies between 150 and 1450 keV, the peak-to-background ratio at a gamma-ray energy of 1.0 MeV was improved by a factor of 2.4 after neutron rejection with a reduction of the photopeak efficiency at 1.0 MeV of only a factor of 1.25.

  10. Limits on Very High Energy Emission from Gamma-Ray Bursts with the Milagro Observatory

    E-Print Network [OSTI]

    The Milagro Collaboration; R. Atkins; W. Benbow; D. Berley; E. Blaufuss; J. Bussons; D. G. Coyne; T. DeYoung; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; L. Fleysher; R. Fleysher; G. Gisler; M. M. Gonzalez; J. A. Goodman; T. J. Haines; E. Hays; C. M. Hoffman; L. A. Kelley; J. E. McEnery; R. S. Miller; A. I. Mincer; M. F. Morales; P. Nemethy; D. Noyes; J. M. Ryan; F. W. Samuelson; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; D. A. Williams; S. Westerhoff; M. E. Wilson; X. Xu; G. B. Yodh

    2004-02-06

    The Milagro telescope monitors the northern sky for 100 GeV to 100 TeV transient emission through continuous very high energy wide-field observations. The large effective area and ~100 GeV energy threshold of Milagro allow it to detect very high energy (VHE) gamma-ray burst emission with much higher sensitivity than previous instruments and a fluence sensitivity at VHE energies comparable to that of dedicated gamma-ray burst satellites at keV to MeV energies. Even in the absence of a positive detection, VHE observations can place important constraints on gamma-ray burst (GRB) progenitor and emission models. We present limits on the VHE flux of 40 s -- 3 h duration transients nearby to earth, as well as sensitivity distributions which have been corrected for gamma-ray absorption by extragalactic background light and cosmological effects. The sensitivity distributions suggest that the typical intrinsic VHE fluence of GRBs is similar or weaker than the keV -- MeV emission, and we demonstrate how these sensitivity distributions may be used to place observational constraints on the absolute VHE luminosity of gamma-ray bursts for any GRB emission and progenitor model.

  11. Signatures of photon and axion-like particle mixing in the gamma-ray burst jet

    E-Print Network [OSTI]

    Olga Mena; Soebur Razzaque; F. Villaescusa-Navarro

    2011-02-07

    Photons couple to Axion-Like Particles (ALPs) or more generally to any pseudo Nambu-Goldstone boson in the presence of an external electromagnetic field. Mixing between photons and ALPs in the strong magnetic field of a Gamma-Ray Burst (GRB) jet during the prompt emission phase can leave observable imprints on the gamma-ray polarization and spectrum. Mixing in the intergalactic medium is not expected to modify these signatures for ALP mass > 10^(-14) eV and/or for gamma ray emission. We also show that when the magnetic field orientation in the propagation region is perpendicular to the field orientation in the production region, the observed synchrotron spectrum becomes steeper than the theoretical prediction and as detected in a sizable fraction of GRB sample. Detection of the correlated polarization and spectral signatures from these steep-spectrum GRBs by gamma-ray polarimeters can be a very powerful probe to discover ALPs. Measurement of gamma-ray polarization from GRBs in general, with high statistics, can also be useful to search for ALPs.

  12. Gamma-Ray Bursts Observed with the Spectrometer SPI Onboard INTEGRAL

    E-Print Network [OSTI]

    A. von Kienlin; A. Rau; V. Beckmann; S. Deluit

    2004-07-07

    The spectrometer SPI is one of the main detectors of ESA's INTEGRAL mission. The instrument offers two interesting and valuable capabilities for the detection of the prompt emission of Gamma-ray bursts. Within a field of view of 16 degrees, SPI is able to localize Gamma-ray bursts with an accuracy of 10 arcmin. The large anticoincidence shield, ACS, consisting of 512 kg of BGO crystals, detects Gamma-ray bursts quasi omnidirectionally above ~70 keV. Burst alerts from SPI/ACS are distributed to the interested community via the INTEGRAL Burst Alert System. The ACS data have been implemented into the 3rd Interplanetary Network and have proven valuable for the localization of bursts using the triangulation method. During the first 8 months of the mission approximately one Gamma-ray burst per month was localized within the field of fiew of SPI and 145 Gamma-ray burst candidates were detected by the ACS from which 40 % have been confirmed by other instruments.

  13. Cosmological dark matter annihilations into gamma-rays - a closer look

    E-Print Network [OSTI]

    Piero Ullio; Lars Bergstrom; Joakim Edsjo; Cedric Lacey

    2002-07-04

    We investigate the prospects of detecting weakly interacting massive particle (WIMP) dark matter by measuring the contribution to the extragalactic gamma-ray radiation induced, in any dark matter halo and at all redshifts, by WIMP pair annihilations into high-energy photons. We perform a detailed analysis of the distinctive spectral features of this signal, recently proposed in a short letter by three of the authors, with emphasis on the signature due to monochromatic gamma-ray yields: the combined effect of cosmological redshift and absorption along the line of sight produces sharp bumps, peaked at the rest frame energy of the lines and asymmetrically smeared to lower energies. The level of the flux depends both on the particle physics scenario for WIMP dark matter and on the question of how dark matter clusters. Uncertainties introduced by the latter are thoroughly discussed implementing a realistic model inspired by results of the state-of-the-art N-body simulations and semi-analytic modeling in the cold dark matter structure formation theory. We also address the question of the potential gamma-ray background originating from blazars, presenting a novel calculation. Comparing the signal with the background, we find that there are viable configurations, in the combined parameter space defined by the particle physics setup and the structure formation scenario, for which the WIMP induced extragalactic gamma-ray signal will be detectable in the new generation of gamma-ray telescopes such as GLAST.

  14. DETECTION OF THE COSMIC {gamma}-RAY HORIZON FROM MULTIWAVELENGTH OBSERVATIONS OF BLAZARS

    SciTech Connect (OSTI)

    Dominguez, A.; Siana, B. [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Finke, J. D. [U.S. Naval Research Laboratory, Space Science Division, Code 7653, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Prada, F. [Campus of International Excellence UAM-CSIC, Cantoblanco, E-28049 Madrid (Spain); Primack, J. R. [Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Kitaura, F. S. [Leibniz-Institut fuer Astrophysik (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Paneque, D., E-mail: albertod@ucr.edu [Kavli Institute for Particle Astrophysics and Cosmology, SLAC, Stanford University, Stanford, CA 94305 (United States)

    2013-06-10

    The first statistically significant detection of the cosmic {gamma}-ray horizon (CGRH) that is independent of any extragalactic background light (EBL) model is presented. The CGRH is a fundamental quantity in cosmology. It gives an estimate of the opacity of the universe to very high energy (VHE) {gamma}-ray photons due to photon-photon pair production with the EBL. The only estimations of the CGRH to date are predictions from EBL models and lower limits from {gamma}-ray observations of cosmological blazars and {gamma}-ray bursts. Here, we present homogeneous synchrotron/synchrotron self-Compton (SSC) models of the spectral energy distributions of 15 blazars based on (almost) simultaneous observations from radio up to the highest energy {gamma}-rays taken with the Fermi satellite. These synchrotron/SSC models predict the unattenuated VHE fluxes, which are compared with the observations by imaging atmospheric Cherenkov telescopes. This comparison provides an estimate of the optical depth of the EBL, which allows us a derivation of the CGRH through a maximum likelihood analysis that is EBL-model independent. We find that the observed CGRH is compatible with the current knowledge of the EBL.

  15. Very Strong TeV Emission as Gamma-Ray Burst Afterglows

    E-Print Network [OSTI]

    Tomonori Totani

    1998-05-20

    Gamma-ray bursts (GRBs) and following afterglows are considered to be produced by dissipation of kinetic energy of a relativistic fireball and radiation process is widely believed as synchrotron radiation or inverse Compton scattering of electrons. We argue that the transfer of kinetic energy of ejecta into electrons may be inefficient process and hence the total energy released by a GRB event is much larger than that emitted in soft gamma-rays, by a factor of \\sim (m_p/m_e). We show that, in this case, very strong emission of TeV gamma-rays is possible due to synchrotron radiation of protons accelerated up to \\sim 10^{21} eV, which are trapped in the magnetic field of afterglow shock and radiate their energy on an observational time scale of \\sim day. This suggests a possibility that GRBs are most energetic in TeV range and such TeV gamma-rays may be detectable from GRBs even at cosmological distances, i.e., z \\sim 1, by currently working ground-based telescopes. Furthermore, this model gives a quantitative explanation for the famous long-duration GeV photons detected from GRB940217. If TeV gamma-ray emission which is much more energetic than GRB photons is detected, it provides a strong evidence for acceleration of protons up to \\sim 10^{21} eV.

  16. A Grey Radiative Transfer Procedure For Gamma-ray Transfer in Supernovae

    E-Print Network [OSTI]

    David J. Jeffery

    1998-11-23

    The gamma-ray transfer in supernovae for the purposes of energy deposition in the ejecta can be approximated fairly accurately as frequency-integrated (grey) radiative transfer using a mean opacity as shown by Swartz, Sutherland, & Harkness (SSH). In SSH's grey radiative transfer procedure (unoptimized) the mean opacity is a pure absorption opacity and it is a constant aside from a usually weak composition dependence. In this paper, we present a variation on the SSH procedure which uses multiple mean opacities which have both absorption and scattering components. There is a mean opacity for each order of Compton scattering. A local-state (LS) approximation permits an analytic solution for the gamma-ray transfer of scattered gamma-ray fields. The LS approximation is admittedly crude, but the scattered fields are always of lesser importance to the energy deposition. We call our procedure the LS grey radiative transfer procedure or LS procedure for short. For a standard Type Ia supernova (SN Ia) model the uncertainty in gamma-ray energy deposition is estimated to be of order 10 % or less. The LS procedure code used for this paper can be obtained by request from the author. For completeness and easy reference, we include in this paper a review of the gamma-ray opacities important in supernovae, a discussion of the appropriate mean opacity prescription, and a discussion of the errors arising from neglecting time-dependent and non-static radiative transfer effects.

  17. Gamma rays from a supernova of type Ia: SN2014J

    E-Print Network [OSTI]

    Diehl, Roland

    2015-01-01

    SN2014J is the closest supernova of type Ia that occured in the last 40 years. This provides an opportunity for unprecedented observational detail and coverage in many astronomical bands, which will help to better understand the still unknown astrophysics of these supernovae. For the first time, such an event occurs sufficiently nearby so that also gamma rays are able to contribute to such investigations. This is important, as the primary source of the supernova light is the radioactive energy from about 0.5 M$_\\odot$ of $^{56}$Ni produced in the explosion, and the gamma rays associated with this decay make the supernova shine for months. The INTEGRAL gamma-ray observatory of ESA has followed the supernova emission for almost 5 months. The characteristic gamma ray lines from the $^{56}$Ni decay chain through $^{56}$Co to $^{56}$Fe have been measured. We discuss these observations, and the implications of the measured gamma-ray line characteristics as they evolve.

  18. The soft gamma-ray pulsar population: an high-energy overview

    E-Print Network [OSTI]

    Kuiper, L

    2015-01-01

    At high-energy gamma-rays (>100 MeV) the Large Area Telescope (LAT) on the Fermi satellite already detected more than 145 rotation-powered pulsars (RPPs), while the number of pulsars seen at soft gamma-rays (20 keV - 30 MeV) remained small. We present a catalogue of 18 non-recycled RPPs from which presently non-thermal pulsed emission has been securely detected at soft gamma-rays above 20 keV, and characterize their pulse profiles and energy spectra. For 14 of them we report new results, (re)analysing mainly data from RXTE, INTEGRAL, XMM-Newton and Chandra. The soft gamma-pulsars are all fast rotators and on average ~9.3x younger and ~ 43x more energetic than the Fermi LAT sample. The majority (11 members) exhibits broad, structured single pulse profiles, and only 6 have double (or even multiple, Vela) pulses. Fifteen soft gamma-ray pulsar show hard power-law spectra in the hard X-ray band and reach maximum luminosities typically in the MeV range. For only 7 of the 18 soft gamma-ray pulsars pulsed emission ha...

  19. Prompt TeV Emission from Cosmic Rays Accelerated by Gamma Ray Bursts Interacting with Surrounding Stellar Wind

    E-Print Network [OSTI]

    Soebur Razzaque; Olga Mena; Charles D. Dermer

    2008-11-24

    Protons accelerated in the internal shocks of a long duration gamma ray burst can escape the fireball as cosmic rays by converting to neutrons. Hadronic interactions of these neutrons inside a stellar wind bubble created by the progenitor star will produce TeV gamma rays via neutral meson decay and synchrotron radiation by charged pion-decay electrons in the wind magnetic field. Such gamma rays should be observable from nearby gamma ray bursts by currently running and upcoming ground-based detectors.

  20. The emission of Gamma Ray Bursts as a test-bed for modified gravity

    E-Print Network [OSTI]

    Salvatore Capozziello; Gaetano Lambiase

    2015-04-15

    The extreme physical conditions of Gamma Ray Bursts can constitute a useful observational laboratory to test theories of gravity where very high curvature regimes are involved. Here we propose a sort of curvature engine capable, in principle, of explaining the huge energy emission of Gamma Ray Bursts. Specifically, we investigate the emission of radiation by charged particles non-minimally coupled to the gravitational background where higher order curvature invariants are present. The coupling gives rise to an additional force inducing a non-geodesics motion of particles. This fact allows a strong emission of radiation by gravitationally accelerated particles. As we will show with some specific model, the energy emission is of the same order of magnitude of that characterizing the Gamma Ray Burst physics. Alternatively, strong curvature regimes can be considered as a natural mechanism for the generation of highly energetic astrophysical events.

  1. Disrupted Globular Clusters Can Explain the Galactic Center Gamma Ray Excess

    E-Print Network [OSTI]

    Brandt, Timothy D

    2015-01-01

    The Fermi satellite has recently detected gamma ray emission from the central regions of our Galaxy. This may be evidence for dark matter particles, a major component of the standard cosmological model, annihilating to produce high-energy photons. We show that the observed signal may instead be generated by millisecond pulsars that formed in dense star clusters in the Galactic halo. Most of these clusters were ultimately disrupted by evaporation and gravitational tides, contributing to a spherical bulge of stars and stellar remnants. The gamma ray amplitude, angular distribution, and spectral signatures of this source may be predicted without free parameters, and are in remarkable agreement with the observations. These gamma rays are from fossil remains of dispersed clusters, telling the history of the Galactic bulge.

  2. Influence of humidity on the scattering of {gamma}-rays in soil

    SciTech Connect (OSTI)

    Cortes, M. L.; Melo, L. M.; Cristancho, F.

    2010-08-04

    Transmission and backscattering of {gamma}-rays have been used to study soil properties such as its porosity, hydraulic conductivity and also for the detection of organic material buried in soil. These applications require a deeper understanding of the interaction of {gamma}-rays with soil. In the present work a study of the interaction of 511 keV {gamma}-rays with layers of sand varying both its humidity and thickness is presented. The experimental set-up uses the positron decay of a {sup 22}Na source, and two gamma detectors connected in fast time-coincidence. Both transmitted and backscattered spectra are obtained. For transmission, the photopeak and the low angle scattered photons are studied, and for backscattering we analyze the number of single and multiple backscattered photons as a function of thickness. Finally, a theoretical model for the derivative of the number of backscattered photons as a function of depth is presented.

  3. Strict Limit on CPT Violation from Polarization of Gamma-Ray Bursts

    E-Print Network [OSTI]

    Kenji Toma; Shinji Mukohyama; Daisuke Yonetoku; Toshio Murakami; Shuichi Gunji; Tatehiro Mihara; Yoshiyuki Morihara; Tomonori Sakashita; Takuya Takahashi; Yudai Wakashima; Hajime Yonemochi; Noriyuki Toukairin

    2012-11-09

    We report the strictest observational verification of CPT invariance in the photon sector, as a result of gamma-ray polarization measurement of distant gamma-ray bursts (GRBs), which are brightest stellar-size explosions in the universe. We detected the gamma-ray polarization of three GRBs with high significance, and the source distances may be constrained by a well-known luminosity indicator for GRBs. For the Lorentz- and CPT-violating dispersion relation E_{\\pm}^2=p^2 \\pm 2\\xi p^3/M_{Pl}, where \\pm denotes different circular polarization states of the photon, the parameter \\xi is constrained as |\\xi|

  4. The emission of Gamma Ray Bursts as a test-bed for modified gravity

    E-Print Network [OSTI]

    Salvatore Capozziello; Gaetano Lambiase

    2015-09-19

    The extreme physical conditions of Gamma Ray Bursts can constitute a useful observational laboratory to test theories of gravity where very high curvature regimes are involved. Here we propose a sort of curvature engine capable, in principle, of explaining the huge energy emission of Gamma Ray Bursts. Specifically, we investigate the emission of radiation by charged particles non-minimally coupled to the gravitational background where higher order curvature invariants are present. The coupling gives rise to an additional force inducing a non-geodesics motion of particles. This fact allows a strong emission of radiation by gravitationally accelerated particles. As we will show with some specific model, the energy emission is of the same order of magnitude of that characterizing the Gamma Ray Burst physics. Alternatively, strong curvature regimes can be considered as a natural mechanism for the generation of highly energetic astrophysical events. Possible applications to cosmology are discussed.

  5. Attosecond gamma-ray pulses via nonlinear Compton scattering in the radiation dominated regime

    E-Print Network [OSTI]

    Li, Jian-Xing; Galow, Benjamin J; Keitel, Christoph H

    2015-01-01

    The interaction of a relativistic electron bunch with a counter-propagating tightly-focused laser beam is investigated for intensities when the dynamics is strongly affected by its own radiation. The Compton scattering spectra of gamma-radiation are evaluated employing a semiclassical description for the laser-driven electron dynamics and a quantum electrodynamical description for the photon emissions. We show for laser facilities under construction that gamma-ray bursts of few hundred attoseconds and dozens of megaelectronvolt photon energies may be detected in the near-backwards direction of the initial electron motion. Tight focussing of the laser beam and radiation reaction are demonstrated to be jointly responsible for such short gamma-ray bursts which are independent of both duration of electron bunch and laser pulse. Furthermore, the stochastic nature of the gamma-photon emission features signatures in the resulting gamma-ray comb in the case of the application of a multi-cycle laser pulse.

  6. Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy

    DOE Patents [OSTI]

    Rowland, Mark S. (Alamo, CA); Howard, Douglas E. (Livermore, CA); Wong, James L. (Dublin, CA); Jessup, James L. (Tracy, CA); Bianchini, Greg M. (Livermore, CA); Miller, Wayne O. (Livermore, CA)

    2007-10-23

    A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

  7. Accurate calculations of the WIMP halo around the Sun and prospects for gamma ray detection

    E-Print Network [OSTI]

    Sofia Sivertsson; Joakim Edsjö

    2009-03-04

    Weakly interacting massive particles (WIMPs) can be captured by heavenly objects, like the Sun. Under the process of being captured by the Sun, they will build up a population of WIMPs around it, that will eventually sink to the core of the Sun. It has been argued with simpler estimates before that this halo of WIMPs around the Sun could be a strong enough gamma ray source to be a detectable signature for WIMP dark matter. We here revisit the problem using detailed Monte Carlo simulations and detailed composition and structure information about the Sun to estimate the size of the gamma ray flux. Compared to earlier estimates, we find that the gamma ray flux from WIMP annihilations in the Sun halo would be negligible and no current or planned detectors would even be able to detect this flux.

  8. The emission of Gamma Ray Bursts as a test-bed for modified gravity

    E-Print Network [OSTI]

    Capozziello, Salvatore

    2015-01-01

    The extreme physical conditions of Gamma Ray Bursts can constitute a useful observational laboratory to test theories of gravity where very high curvature regimes are involved. Here we propose a sort of curvature engine capable, in principle, of explaining the huge energy emission of Gamma Ray Bursts. Specifically, we investigate the emission of radiation by charged particles non-minimally coupled to the gravitational background where higher order curvature invariants are present. The coupling gives rise to an additional force inducing a non-geodesics motion of particles. This fact allows a strong emission of radiation by gravitationally accelerated particles. As we will show with some specific model, the energy emission is of the same order of magnitude of that characterizing the Gamma Ray Burst physics. Alternatively, strong curvature regimes can be considered as a natural mechanism for the generation of highly energetic astrophysical events.

  9. Present and future gamma-ray probes of the Cygnus OB2 environment

    SciTech Connect (OSTI)

    Anchordoqui, Luis A. [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, Torre C5, 2a planta, 08193 Barcelona (Spain); Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States); Goldberg, Haim [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Moore, Russell D. [Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States); Palomares-Ruiz, Sergio [Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Torres, Diego F. [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, Torre C5, 2a planta, 08193 Barcelona (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA) (Spain); Weiler, Thomas J. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

    2009-11-15

    The MAGIC Collaboration has provided new observational data pertaining to the TeV J2032+4130 gamma-ray source (within the Cygnus OB2 region), for energies E{sub {gamma}}>400 GeV. It is then appropriate to update the impact of these data on gamma-ray production mechanisms in stellar associations. We consider two mechanisms of gamma-ray emission, pion production and decay (PION) and photoexcitation of high-energy nuclei followed by prompt photoemission from the daughter nuclei (A*). We find that while the data can be accommodated with either scenario, the A* features a spectral bump, corresponding to the threshold for exciting the giant dipole resonance, which can serve to discriminate between them. We comment on neutrino emission and detection from the region if the PION and/or A* processes are operative. We also touch on the implications for this analysis of future Fermi and Cerenkov Telescope array data.

  10. Neutron and gamma-ray emission from palladium deuteride under supercritical conditions

    SciTech Connect (OSTI)

    Jorne, J. )

    1991-03-01

    This paper reports on palladium which is exposed to pressurized deuterium gas at 60 atm and 198 K and the temperature is cycled up to 593 K, beyond the critical point for palladium deuteride. Two neutron and gamma-ray counters, located near the pressurized vessel, show evidence of excess neutrons and gamma rays beyond the background level. Similar experiments with an empty cell or with a hydrogen-palladium cell show no excess in neutrons and gamma rays beyond the background levels. If the excess in neutrons is due to fusion, a corresponding fusion rate of 10{sup 21} fusion/d-d {center dot} s can be estimated, which is comparable to the rate of 10{sup 23} for electrochemically induced fusion.

  11. Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources

    SciTech Connect (OSTI)

    Hartemann, F V; Albert, F; Anderson, S G; Bayramian, A J; Cross, R R; Ebbers, C A; Gibson, D J; Houck, T L; Marsh, R A; Messerly, M J; Siders, C W; McNabb, D P; Barty, C J; Adolphsen, C E; Chu, T S; Jongewaard, E N; Tantawi, S G; Vlieks, A E; Wang, F; Wang, J W; Raubenheimer, T O; Ighigeanu, D; Toma, M; Cutoiu, D

    2011-08-31

    Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabled by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).

  12. Gamma-Ray Polarimetry of Two X-Class Solar Flares

    E-Print Network [OSTI]

    Steven E. Boggs; W. Coburn; E. Kalemci

    2005-10-19

    We have performed the first polarimetry of solar flare emission at gamma-ray energies (0.2-1 MeV). These observations were performed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) for two large flares: the GOES X4.8-class solar flare of 2002 July 23, and the X17-class flare of 2003 October 28. We have marginal polarization detections in both flares, at levels of 21% +/- 9% and -11% +/- 5% respectively. These measurements significantly constrain the levels and directions of solar flare gamma-ray polarization, and begin to probe the underlying electron distributions.

  13. Implications Of A Dark Sector U(1) For Gamma Ray Bursts

    E-Print Network [OSTI]

    Tom Banks; Willy Fischler; Dustin Lorshbough; Walter Tangarife

    2014-04-29

    We discuss the implications for gamma ray burst studies, of a dark unbroken $U(1)_D$ sector that couples predominantly through gravity to the visible sector. The dominant dark matter component remains neutral under $U(1)_D$. The collapsar model is assumed to explain the origin of long gamma ray bursts. The main idea is that by measuring the change in stellar black hole spin during the duration of the GRB, one can make inferences about the existence of a dark matter accretion disk. This could potentially provide evidence for the existence for a $U(1)_D$ sector.

  14. Green's functions for transmission of X-rays and gamma-rays through cold media

    E-Print Network [OSTI]

    P. Magdziarz; A. A. Zdziarski

    1996-07-03

    Using a Monte Carlo method, we study Compton scattering and absorption of X-rays and gamma-rays in cold media. We consider transmission of X/gamma-rays through a shell of an arbitrary optical depth, for which we derive energy-dependent Green's functions. Fitting the Green functions with simple analytical formulae is in progress. We also present a simple treatment of the effect of absorption on Green's functions for Compton scattering, which allow to treat media with an arbitrary ionization state and chemical composition. Our transmission Green's functions allow to treat Thomson-thick absorbers, e.g. molecular tori of Seyfert 2s.

  15. Detection and measurement of gamma rays with the AMS-02 detector

    E-Print Network [OSTI]

    Gentile, S

    2007-01-01

    The Alpha Magnetic Spectrometer (AMS-02) will be installed on the International Space Station (ISS). The gamma rays can be measured through gamma conversion into e+e- pair, before reaching the Silicon Tracker or by measurement of a photon hitting directly the Electromagnetic Calorimeter (ECAL). AMS-02 will provide precise gamma measurements in the GeV energy range, which is particularly relevant for Dark Matter searches. In addition, the good angular resolution and identification capabilities of the detector will allow studies of the main galactic and extra-galactic sources, diffuse gamma background and Gamma Ray Bursts.

  16. Detection and measurement of gamma rays with the AMS-02 detector

    E-Print Network [OSTI]

    Simonetta Gentile

    2007-02-12

    The Alpha Magnetic Spectrometer (AMS-02) will be installed on the International Space Station (ISS). The gamma rays can be measured through gamma conversion into e+e- pair, before reaching the Silicon Tracker or by measurement of a photon hitting directly the Electromagnetic Calorimeter (ECAL). AMS-02 will provide precise gamma measurements in the GeV energy range, which is particularly relevant for Dark Matter searches. In addition, the good angular resolution and identification capabilities of the detector will allow studies of the main galactic and extra-galactic sources, diffuse gamma background and Gamma Ray Bursts.

  17. A field-deployable gamma-ray spectrometer utilizing xenon at high pressure

    SciTech Connect (OSTI)

    Smith, G.C.; Mahler, G.J.; Yu, B.; Salwen, C.; Kane, W.R.; Lemley, J.R.

    1996-10-01

    Prototype gamma-ray spectrometers utilizing xenon gas at high pressure, suitable for applications in the nuclear safeguards, arms control, and nonproliferation communities, have been developed at Brookhaven National Laboratory (BNL). These spectrometers function as ambient-temperature ionization chambers detecting gamma rays with good efficiency in the energy range 50 keV - 2 MeV, with an energy resolution intermediate between semiconductor (Ge) and scintillation (NaI) spectrometers. They are capable of prolonged, low-power operation without a requirement for cryogenic fluids or other cooling mechanisms, and with the addition of small quantities of {sup 3}He gas, can function simultaneously as efficient thermal neutron detectors.

  18. A Method to Search for Local Sources of Short Duration Bursts of Superhigh Energy Gamma Rays

    E-Print Network [OSTI]

    E. N. Alexeyev; D. D. Djappuev; A. U. Kudjaev; S. Kh. Ozrokov

    2001-04-09

    A method of a search for local sources of superhigh energy gamma rays is described in the paper.It is shown that the method is more effective then the usually used method extracting excess from total intensity if gamma ray burst durations are short.Using the suggested method,the information detected with the Baksan installation ``Carpet'' during 1992-1996 years was analyzed.An excess of event numbers was found at the confidence level of 6.5$\\sigma$ in the direction to Mrk 501.

  19. Young Pulsars and the Galactic Center GeV Gamma-ray Excess

    E-Print Network [OSTI]

    Ryan M. O'Leary; Matthew D. Kistler; Matthew Kerr; Jason Dexter

    2015-04-09

    Studies of Fermi data indicate an excess of GeV gamma rays around the Galactic center (GC), possibly due to dark matter. We show that young gamma-ray pulsars can yield a similar signal. First, a high concentration of GC supernovae naturally leads to a population of kicked pulsars symmetric about the GC. Second, while very-young pulsars with soft spectra reside near the Galactic plane, pulsars with spectra that have hardened with age accumulate at larger angles. This combination, including unresolved foreground pulsars, traces the morphology and spectrum of the Excess.

  20. Young Pulsars and the Galactic Center GeV Gamma-ray Excess

    E-Print Network [OSTI]

    O'Leary, Ryan M; Kerr, Matthew; Dexter, Jason

    2015-01-01

    Studies of Fermi data indicate an excess of GeV gamma rays around the Galactic center (GC), possibly due to dark matter. We show that young gamma-ray pulsars can yield a similar signal. First, a high concentration of GC supernovae naturally leads to a population of kicked pulsars symmetric about the GC. Second, while very-young pulsars with soft spectra reside near the Galactic plane, pulsars with spectra that have hardened with age accumulate at larger angles. This combination, including unresolved foreground pulsars, traces the morphology and spectrum of the Excess.

  1. White Paper on the Status and Future of Ground-based Gamma-ray Astronomy

    E-Print Network [OSTI]

    H. Krawczynski; J. Buckley; K. Byrum; C. Dermer; B. Dingus; A. Falcone; P. Kaaret; F. Krennrich; M. Pohl; V. Vassiliev; D. A. Williams; for the White Paper Team

    2007-09-05

    In recent years, ground-based gamma-ray observatories have made a number of important astrophysical discoveries which have attracted the attention of the wider scientific community. The Division of Astrophysics of the American Physical Society has requested the preparation of a white paper on the status and future of ground-based gamma-ray astronomy to define the science goals of the future observatory, to determine the performance specifications, and to identify the areas of necessary technology development. In this contribution we give a brief overview of the activities of the current white paper team and invite the international community to contribute to the white paper.

  2. White Paper on the Status and Future of Ground-based Gamma-ray Astronomy

    E-Print Network [OSTI]

    Krawczynski, H; Byrum, K; Dermer, C; Dingus, B; Falcone, A; Kaaret, Philip; Krennrich, F; Pohl, M; Vasilev, V; Williams, D A

    2007-01-01

    In recent years, ground-based gamma-ray observatories have made a number of important astrophysical discoveries which have attracted the attention of the wider scientific community. The Division of Astrophysics of the American Physical Society has requested the preparation of a white paper on the status and future of ground-based gamma-ray astronomy to define the science goals of the future observatory, to determine the performance specifications, and to identify the areas of necessary technology development. In this contribution we give a brief overview of the activities of the current white paper team and invite the international community to contribute to the white paper.

  3. SHORT GAMMA-RAY BURSTS AND DARK MATTER SEEDING IN NEUTRON STARS

    SciTech Connect (OSTI)

    Perez-Garcia, M. Angeles [Department of Fundamental Physics and IUFFyM, University of Salamanca, Plaza de la Merced s/n, E-37008 Salamanca (Spain); Daigne, F.; Silk, J., E-mail: mperezga@usal.es, E-mail: daigne@iap.fr, E-mail: j.silk1@physics.ox.ac.uk [UPMC-CNRS, UMR7095, Institut d'Astrophysique de Paris, F-75014 Paris (France)

    2013-05-10

    We present a mechanism based on internal self-annihilation of dark matter accreted from the galactic halo in the inner regions of neutron stars that may trigger full or partial conversion into a quark star. We explain how this effect may induce a gamma-ray burst (GRB) that could be classified as short, according to the usual definition based on time duration of the prompt gamma-ray emission. This mechanism differs in many aspects from the most discussed scenario associating short GRBs with compact object binary mergers. We list possible observational signatures that should help distinguish between these two possible classes of progenitors.

  4. THE FERMI GBM GAMMA-RAY BURST CATALOG: THE FIRST TWO YEARS

    SciTech Connect (OSTI)

    Paciesas, William S.; Bhat, P. N.; Briggs, Michael S.; Burgess, J. Michael; Chaplin, Vandiver; Connaughton, Valerie; Goldstein, Adam; Guiriec, Sylvain; Meegan, Charles A.; Van der Horst, Alexander J.; Von Kienlin, Andreas; Diehl, Roland; Foley, Suzanne; Greiner, Jochen; Gruber, David; Bissaldi, Elisabetta; Fishman, Gerald J.; Gibby, Melissa; Giles, Misty; and others

    2012-03-01

    The Fermi Gamma-ray Burst Monitor (GBM) is designed to enhance the scientific return from Fermi in studying gamma-ray bursts (GRBs). In its first two years of operation GBM triggered on 491 GRBs. We summarize the criteria used for triggering and quantify the general characteristics of the triggered GRBs, including their locations, durations, peak flux, and fluence. This catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

  5. Spectral Lags of Gamma-Ray Bursts from Primordial Black Hole (PBH) Evaporations

    E-Print Network [OSTI]

    T. N. Ukwatta; J. H. MacGibbon; W. C. Parke; K. S. Dhuga; A. Eskandarian; N. Gehrels; L. Maximon; D. C. Morris

    2009-08-14

    Primordial Black Holes (PBHs), which may have been created in the early Universe, are predicted to be detectable by their Hawking radiation. PBHs with an initial mass of 5.0 * 10^14 g should be expiring today with a burst of high energy particles. Evaporating PBHs in the solar neighborhood are candidate Gamma-Ray Bursts (GRBs) progenitors. We propose spectral lag, which is the temporal delay between the high energy photon pulse and the low energy photon pulse, as a possible method to detect PBH evaporation events with the Fermi Gamma-ray Space Telescope Observatory.

  6. Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts

    E-Print Network [OSTI]

    V. Predoi; for the LIGO Scientific Collaboration; for the Virgo Collaboration; K. Hurley; for IPN

    2011-12-07

    We outline the scientific motivation behind a search for gravitational waves associated with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and Virgo's first science run. The IPN localisation of short gamma ray bursts is limited to extended error boxes of different shapes and sizes and a search on these error boxes poses a series of challenges for data analysis. We will discuss these challenges and outline the methods to optimise the search over these error boxes.

  7. Conversion of neutron stars to strange stars as the central engine of gamma-ray bursts

    E-Print Network [OSTI]

    Ignazio Bombaci; Bhaskar Datta

    2000-01-27

    We study the conversion of a neutron star to a strange star as a possible energy source for gamma-ray bursts. We use different recent models for the equation of state of neutron star matter and strange quark matter. We show that the total amount of energy liberated in the conversion is in the range of (1-4) 10^{53} ergs (one order of magnitude larger than previous estimates) and is in agreement with the energy required to power gamma-ray burst sources at cosmological distances.

  8. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOE Patents [OSTI]

    Neal, John S.; Mihalczo, John T.

    2006-11-28

    A detector system that combines a .sup.6Li loaded glass fiber scintillation thermal neutron detector with a fast scintillation detector in a single layered structure. Detection of thermal and fast neutrons and ionizing electromagnetic radiation is achieved in the unified detector structure. The fast scintillator replaces the polyethelene moderator layer adjacent the .sup.6Li loaded glass fiber panel of the neutron detector and acts as the moderator for the glass fibers. Fast neutrons, x-rays and gamma rays are detected in the fast scintillator. Thermal neutrons, x-rays and gamma rays are detected in the glass fiber scintillator.

  9. Lag-luminosity relation in gamma-ray burst X-ray flares

    SciTech Connect (OSTI)

    Margutti, R.

    2010-10-15

    In strict analogy to prompt pulses, X-ray flares observed by Swift-XRT in long Gamma-Ray Bursts define a lag-luminosity relation: L{sub p,iso}{sup 0.3-10} k{sup eV} {infinity}t{sub lag}{sup -0.95{+-}0.23}. The lag-luminosity is proven to be a fundamental law extending {approx}5 decades in time and {approx}5 in energy. This is direct evidence that GRB X-ray flares and prompt gamma-ray pulses are produced by the same mechanism.

  10. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOE Patents [OSTI]

    Neal, John S. (Knoxville, TN); Mihalczo, John T (Oak Ridge, TN)

    2007-10-30

    A system for detecting fissile and fissionable material originating external to the system includes: a .sup.6Li loaded glass fiber scintillator for detecting thermal neutrons, x-rays and gamma rays; a fast scintillator for detecting fast neutrons, x-rays and gamma rays, the fast scintillator conjoined with the glass fiber scintillator such that the fast scintillator moderates fast neutrons prior to their detection as thermal neutrons by the glass fiber scintillator; and a coincidence detection system for processing the time distributions of arriving signals from the scintillators.

  11. Compton Electrons and Electromagnetic Pulse in Supernovae and Gamma-Ray Bursts

    E-Print Network [OSTI]

    J. I. Katz

    1999-08-19

    When gamma-rays emerge from a central source they may undergo Compton scattering in surrounding matter. The resulting Compton-scattered electrons radiate. Coherent radiation by such Compton electrons follows nuclear explosions above the Earth's atmosphere. Particle acceleration in instabilities produced by Compton electron currents may explain the radio emission by SN1998bw. Bounds on coherent radiation are suggested for supernovae and gamma-ray bursts; these bounds are very high, but it is unknown if coherent radiation occurs in these objects.

  12. Cross Sections for the Electron Activation of Gamma-Ray Fluorescence

    E-Print Network [OSTI]

    Silviu Olariu; Agata Olariu; Yoshiaki Ito; Takeshi Mukoyama

    2000-06-26

    We report cross sections for the direct excitation of gamma-ray transitions up to 200 keV by the transient electromagnetic fields of electrons from a beam, for incident kinetic energies of 500 keV and 5 MeV. The cross sections for the electron activation of gamma-ray fluorescence are of the order of 300 nanobarns for an electron incident kinetic energy of 500 keV, and are of the order of 10 microbarns for an electron incident kinetic energy of 5 MeV. The electron excitation of nuclear transitions may lead to the development of pulsed sources of gamma radiation of narrowly defined energy.

  13. OPTICAL CLASSIFICATION OF GAMMA-RAY BURSTS IN THE SWIFT ERA

    SciTech Connect (OSTI)

    Van der Horst, A. J.; Kouveliotou, C.; Gehrels, N.; Cannizzo, J. K.; Rol, E.; Wijers, R. A. M. J.; Racusin, J.; Burrows, D. N.

    2009-07-10

    We propose a new method for the classification of optically dark gamma-ray bursts (GRBs), based on the X-ray and optical-to-X-ray spectral indices of GRB afterglows, and utilizing the spectral capabilities of Swift. This method depends less on model assumptions than previous methods, and can be used as a quick diagnostic tool to identify optically sub-luminous bursts. With this method we can also find GRBs that are extremely bright at optical wavelengths. We show that the previously suggested correlation between the optical darkness and the X-ray/gamma-ray brightness is merely an observational selection effect.

  14. The Gamma Ray Burst section of the White Paper on the Status and Future of Very High Energy Gamma Ray Astronomy A Brief Preliminary Report

    E-Print Network [OSTI]

    Falcone, A D; Baring, M G; Blandford, R; Connaughton, V; Coppi, P; Dermer, C; Dingus, B; Fryer, C; Gehrels, N; Granot, J; Horan, D; Katz, J I; Kühn, K; Mészáros, P; Norris, J; Parkinson, P Saz; Peér, A; Ramirez-Ruiz, E; Razzaque, S; Wang, X; Zhang, B

    2008-01-01

    This is a short report on the preliminary findings of the gamma ray burst (GRB) working group for the white paper on the status and future of very high energy (VHE; >50 GeV) gamma-ray astronomy. The white paper discusses the status of past and current attempts to observe GRBs at GeV-TeV energies, including a handful of low-significance, possible detections. The white paper concentrates on the potential of future ground-based gamma-ray experiments to observe the highest energy emission ever recorded for GRBs, particularly for those that are nearby and have high Lorentz factors in the GRB jet. It is clear that the detection of VHE emission would have strong implications for GRB models, as well as cosmic ray origin. In particular, the extended emission phase (including both afterglow emission and possible flaring) of nearby long GRBs could provide the best possibility for detection. The difficult-to-obtain observations during the prompt phase of nearby long GRBs and short GRBs could also provide particularly str...

  15. The Gamma Ray Burst section of the White Paper on the Status and Future of Very High Energy Gamma Ray Astronomy: A Brief Preliminary Report

    E-Print Network [OSTI]

    A. D. Falcone; D. A. Williams; M. G. Baring; R. Blandford; V. Connaughton; P. Coppi; C. Dermer; B. Dingus; C. Fryer; N. Gehrels; J. Granot; D. Horan; J. I. Katz; K. Kuehn; P. Meszaros; J. Norris; P. Saz Parkinson; A. Peer; E. Ramirez-Ruiz; S. Razzaque; X. Wang; B. Zhang

    2008-04-15

    This is a short report on the preliminary findings of the gamma ray burst (GRB) working group for the white paper on the status and future of very high energy (VHE; >50 GeV) gamma-ray astronomy. The white paper discusses the status of past and current attempts to observe GRBs at GeV-TeV energies, including a handful of low-significance, possible detections. The white paper concentrates on the potential of future ground-based gamma-ray experiments to observe the highest energy emission ever recorded for GRBs, particularly for those that are nearby and have high Lorentz factors in the GRB jet. It is clear that the detection of VHE emission would have strong implications for GRB models, as well as cosmic ray origin. In particular, the extended emission phase (including both afterglow emission and possible flaring) of nearby long GRBs could provide the best possibility for detection. The difficult-to-obtain observations during the prompt phase of nearby long GRBs and short GRBs could also provide particularly strong constraints on the opacity and bulk Lorentz factors surrounding the acceleration site. The synergy with upcoming and existing observatories will, of course, be critical for both identification of GRBs and for multiwavelength/multimessenger studies.

  16. Short gamma-ray bursts in the "time-reversal" scenario

    E-Print Network [OSTI]

    Riccardo Ciolfi; Daniel M. Siegel

    2015-01-27

    Short gamma-ray bursts (SGRBs) are among the most luminous explosions in the Universe and their origin still remains uncertain. Observational evidence favors the association with binary neutron star or neutron star-black hole (NS-BH) binary mergers. Leading models relate SGRBs to a relativistic jet launched by the BH-torus system resulting from the merger. However, recent observations have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations $\\sim10^2\\!-\\!10^5~\\mathrm{s}$, suggesting continuous energy injection from a long-lived central engine, which is incompatible with the short ($\\lesssim1~\\mathrm{s}$) accretion timescale of a BH-torus system. The formation of a supramassive NS, resisting the collapse on much longer spin-down timescales, can explain these afterglow durations, but leaves serious doubts on whether a relativistic jet can be launched at merger. Here we present a novel scenario accommodating both aspects, where the SGRB is produced after the collapse of a supramassive NS. Early differential rotation and subsequent spin-down emission generate an optically thick environment around the NS consisting of a photon-pair nebula and an outer shell of baryon-loaded ejecta. While the jet easily drills through this environment, spin-down radiation diffuses outwards on much longer timescales and accumulates a delay that allows the SGRB to be observed before (part of) the long-lasting X-ray signal. By analyzing diffusion timescales for a wide range of physical parameters, we find delays that can generally reach $\\sim10^5~\\mathrm{s}$, compatible with observations. The success of this fundamental test makes this "time-reversal" scenario an attractive alternative to current SGRB models.

  17. Searches for inspiral gravitational waves associated with short gamma-ray bursts in LIGO's fifth and Virgo's first science run

    E-Print Network [OSTI]

    Alexander Dietz

    2010-06-16

    This brief report describes the search for gravitational-wave inspiral signals from short gamma-ray bursts. Since these events are probably created by the merger of two compact objects, a targeted search with a lower threshold can be made. The data around 22 short gamma-ray bursts have been analyzed.

  18. Discovery of High-Energy Gamma-Ray Pulsations from PSR J2021+3651 with AGILE

    E-Print Network [OSTI]

    J. P. Halpern; F. Camilo; A. Giuliani; E. V. Gotthelf; M. A. McLaughlin; R. Mukherjee; A. Pellizzoni; S. M. Ransom; M. S. E. Roberts; M. Tavani

    2008-09-30

    Discovered after the end of the Compton Gamma-Ray Observatory mission, the radio pulsar PSR J2021+3651 was long considered a likely counterpart of the high-energy gamma-ray source 2CG 075+00 = 3EG J2021+3716 = GeV J2020+3658, but it could not be confirmed due to the lack of a contemporaneous radio pulsar ephemeris to fold the sparse, archival gamma-ray photons. Here, we report the discovery of gamma-ray pulsations from PSR J2021+3651 in the 100-1500 MeV range using data from the AGILE satellite gathered over 8 months, folded on a densely sampled, contemporaneous radio ephemeris obtained for this purpose at the Green Bank Telescope. The gamma-ray pulse consists of two sharp peaks separated by 0.47+/-0.01 cycles. The single radio pulse leads the first gamma-ray peak by 0.165+/-0.010 cycles. These properties are similar to those of other gamma-ray pulsars, and the phase relationship of the peaks can be interpreted in the context of the outer-gap accelerator model for gamma-ray emission. Pulse-phase resolved images show that there is only one dominant source, AGL J2020.5+3653 = PSR J2021+3651 in the region previously containing confused sources 3EG J2021+3716 and 3EG J2016+3657.

  19. SWIFT PANCHROMATIC OBSERVATIONS OF THE BRIGHT GAMMA-RAY BURST GRB 050525a A. J. Blustin,1

    E-Print Network [OSTI]

    Zhang, Bing

    SWIFT PANCHROMATIC OBSERVATIONS OF THE BRIGHT GAMMA-RAY BURST GRB 050525a A. J. Blustin,1 D. Band,2 S. Barthelmy,2 P. Boyd,2 M. Capalbi,3 S. T. Holland,2 F. E. Marshall,2 K. O. Mason,1 M. Perri,3 T ABSTRACT The bright gamma-ray burst GRB 050525a has been detected with the Swift observatory, providing

  20. A NEW POPULATION OF HIGH-REDSHIFT SHORT-DURATION GAMMA-RAY BURSTS E. Berger,1,2,3

    E-Print Network [OSTI]

    Sheppard, Scott S.

    A NEW POPULATION OF HIGH-REDSHIFT SHORT-DURATION GAMMA-RAY BURSTS E. Berger,1,2,3 D. B. Fox,4 P. A The redshift distribution of the short-duration gamma-ray bursts (GRBs) is a crucial, but currently fragmentary rays: bursts Online material: color figures 1. INTRODUCTION The redshift distribution of the short