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1

Atomic Inference from Weak Gravitational Lensing Data  

SciTech Connect

We present a novel approach to reconstructing the projected mass distribution from the sparse and noisy weak gravitational lensing shear data. The reconstructions are regularized via the knowledge gained from numerical simulations of clusters, with trial mass distributions constructed from n NFW profile ellipsoidal components. The parameters of these ''atoms'' are distributed a priori as in the simulated clusters. Sampling the mass distributions from the atom parameter probability density function allows estimates of the properties of the mass distribution to be generated, with error bars. The appropriate number of atoms is inferred from the data itself via the Bayesian evidence, and is typically found to be small, reecting the quality of the data. Ensemble average mass maps are found to be robust to the details of the noise realization, and succeed in recovering the demonstration input mass distribution (from a realistic simulated cluster) over a wide range of scales. As an application of such a reliable mapping algorithm, we comment on the residuals of the reconstruction and the implications for predicting convergence and shear at specific points on the sky.

Marshall, Phil; /KIPAC, Menlo Park

2005-12-14T23:59:59.000Z

2

Weak gravitational lensing as a method to constrain unstable dark matter  

SciTech Connect

The nature of the dark matter remains a mystery. The possibility of an unstable dark matter particle decaying to invisible daughter particles has been explored many times in the past few decades. Meanwhile, weak gravitational lensing shear has gained a lot of attention as a probe of dark energy, though it was previously considered a dark matter probe. Weak lensing is a useful tool for constraining the stability of the dark matter. In the coming decade a number of large galaxy imaging surveys will be undertaken and will measure the statistics of cosmological weak lensing with unprecedented precision. Weak lensing statistics are sensitive to unstable dark matter in at least two ways. Dark matter decays alter the matter power spectrum and change the angular diameter distance-redshift relation. We show how measurements of weak lensing shear correlations may provide the most restrictive, model-independent constraints on the lifetime of unstable dark matter. Our results rely on assumptions regarding nonlinear evolution of density fluctuations in scenarios of unstable dark matter and one of our aims is to stimulate interest in theoretical work on nonlinear structure growth in unstable dark matter models.

Wang Meiyu; Zentner, Andrew R. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

2010-12-15T23:59:59.000Z

3

Bayesian Photometric Redshifts for Weak Lensing Applications  

E-Print Network (OSTI)

The next generation of weak gravitational lensing surveys is capable of generating good measurements of cosmological parameters, provided that, amongst other requirements, adequate redshift information is available for the background galaxies that are measured. It is frequently assumed that photometric redshift techniques provide the means to achieve this. Here we compare Bayesian and frequentist approaches to photometric redshift estimation, particularly at faint magnitudes. We identify and discuss the biases that are inherent in the various methods, and describe an optimum Bayesian method for extracting redshift distributions from photometric data.

Edward Edmondson; Lance Miller; Christian Wolf

2006-07-13T23:59:59.000Z

4

The Environments of SLACS Gravitational Lenses  

E-Print Network (OSTI)

We report on an investigation of the environments of the SLACS sample of gravitational lenses. The local and global environments of the lenses are characterized using SDSS photometry and, when available, spectroscopy. We find that the lens systems that are best modelled with steeper than isothermal density profiles are more likely to have close companions than lenses with shallower than isothermal profiles. This suggests that the profile steepening may be caused by interactions with a companion galaxy as indicated by N-body simulations of group galaxies. The global environments of the SLACS lenses are typical of non-lensing SDSS galaxies with comparable properties to the lenses, and the richnesses of the lens groups are not as strongly correlated with the lens density profiles as the local environments. Furthermore, we investigate the possibility of line-of-sight contamination affecting the lens models but do not find a significant over-density of sources compared to lines of sight without lenses.

M. W. Auger

2007-10-09T23:59:59.000Z

5

Gravitational lensing of STU black holes  

E-Print Network (OSTI)

In this paper we study gravitational lensing by STU black holes. We considered extremal limit of two special cases of zero-charged and one-charged black holes, and obtain the deflection angle. We find that the black hole charge increases the deflection angle.

Hassan Saadat

2013-06-03T23:59:59.000Z

6

Gravitational lensing of STU black holes  

E-Print Network (OSTI)

In this paper we study gravitational lensing by STU black holes. We considered extremal limit of two special cases of zero-charged and one-charged black holes, and obtain the deflection angle. We find that the black hole charge increases the deflection angle.

Saadat, Hassan

2013-01-01T23:59:59.000Z

7

Gravitational lensing in a non-uniform plasma  

E-Print Network (OSTI)

We develop a model of gravitational lensing in a non-uniform plasma. When a gravitating body is surrounded by a plasma, the lensing angle depends on the frequency of the electromagnetic wave, due to dispersion properties of plasma, in presence of a plasma inhomogeneity, and of a gravity. The second effect leads, even in a uniform plasma, to a difference of the gravitational photon deflection angle from the vacuum case, and to its dependence on the photon frequency. We take into account both effects, and derive the expression for the lensing angle in the case of a strongly nonuniform plasma in presence of the gravitation. Dependence of the lensing angle on the photon frequency in a homogeneous plasma resembles the properties of a refractive prism spectrometer, which strongest action is for very long radiowaves. We discuss the observational appearances of this effect for the gravitational lens with a Schwarzschild metric, surrounded by a uniform plasma. We obtain formulae for the lensing angle and the magnification factors in this case and discuss a possibility of observation of this effect by the planned VLBI space project Radioastron. We also consider models with a nonuniform plasma distribution. For different gravitational lens models we compare the corrections to the vacuum lensing due to the gravitational effect in plasma, and due to the plasma inhomogeneity. We have shown that the gravitational effect could be detected in the case of a hot gas in the gravitational field of a galaxy cluster.

G. S. Bisnovatyi-Kogan; O. Yu. Tsupko

2010-06-11T23:59:59.000Z

8

Weak Lensing Determination of the Mass in Galaxy Halos  

E-Print Network (OSTI)

We detect the weak gravitational lensing distortion of 450,000 background galaxies (20projected radius of 200 \\hkpc, the shear profile is consistent with an isothermal profile with circular velocity 164+-20 km/s for an L* galaxy, consistent with typical disk rotation at this luminosity. This halo mass normalization, combined with the halo profile derived by Fischer et al (2000) from lensing analysis SDSS data, places a lower limit of (2.7+-0.6) x 10^{12}h^{-1} solar masses on the mass of an L* galaxy halo, in good agreement with satellite galaxy studies. Given the known luminosity function of LCRS galaxies, and the assumption that $M\\propto L^\\beta$ for galaxies, we determine that the mass within 260\\hkpc of normal galaxies contributes $\\Omega=0.16\\pm0.03$ to the density of the Universe (for $\\beta=1$) or $\\Omega=0.24\\pm0.06$ for $\\beta=0.5$. These lensing data suggest that $0.6agreement with the usual $\\beta\\approx0.5$ Faber-Jackson or Tully-Fisher scaling. This is the most complete direct inventory of the matter content of the Universe to date.

D. R. Smith; G. M. Bernstein; P. Fischer; R. M. Jarvis

2000-10-03T23:59:59.000Z

9

A Catalog of Mass Models for Gravitational Lensing  

E-Print Network (OSTI)

Many different families of mass models are used in modern applications of strong gravitational lensing. I review a wide range of popular models, with two points of emphasis: (1) a discussion of strategies for building models suited to a particular lensing problem; and (2) a summary of technical results for a canonical set of models. All of the models reviewed here are included in publicly-available lensing software called gravlens.

Charles R. Keeton

2001-02-20T23:59:59.000Z

10

Weak Lensing Mass Reconstruction of the Galaxy Cluster Abell 209  

E-Print Network (OSTI)

Weak lensing applied to deep optical images of clusters of galaxies provides a powerful tool to reconstruct the distribution of the gravitating mass associated to these structures. We use the shear signal extracted by an analysis of deep exposures of a region centered around the galaxy cluster Abell 209, at redshift z=0.2, to derive both a map of the projected mass distribution and an estimate of the total mass within a characteristic radius. We use a series of deep archival R-band images from CFHT-12k, covering an area of 0.3 deg^2. We determine the shear of background galaxy images using a new implementation of the modified Kaiser-Squires-Broadhurst pipeline for shear determination, which we has been tested against the ``Shear TEsting Program 1 and 2'' simulations. We use mass aperture statistics to produce maps of the 2 dimensional density distribution, and parametric fits using both Navarro-Frenk-White (NFW) and singular-isothermal-sphere profiles to constrain the total mass. The projected mass distribution shows a pronounced asymmetry, with an elongated structure extending from the SE to the NW. This is in general agreement with the optical distribution previously found by other authors. A similar elongation was previously detected in the X-ray emission map, and in the distribution of galaxy colours. The circular NFW mass profile fit gives a total mass of M_{200} = 7.7^{+4.3}_{-2.7} 10^{14} solar masses inside the virial radius r_{200} = 1.8\\pm 0.3 Mpc. The weak lensing profile reinforces the evidence for an elongated structure of Abell 209, as previously suggested by studies of the galaxy distribution and velocities.

S. Paulin-Henriksson; V. Antonuccio-Delogu; C. P. Haines; M. Radovich; A. Mercurio; U. Becciani

2007-01-28T23:59:59.000Z

11

Gravitational Lensing Characteristics of the Transparent Sun  

E-Print Network (OSTI)

The transparent Sun is modeled as a spherically symmetric and centrally condensed gravitational lens using recent Standard Solar Model (SSM) data. The Sun's minimum focal length is computed to a refined accuracy of 23.5 +/- 0.1 AU, just beyond the orbit of Uranus. The Sun creates a single image of a distant point source visible to observers inside this minimum focal length and to observers sufficiently removed from the line connecting the source through the Sun's center. Regions of space are mapped where three images of a distant point source are created, along with their associated magnifications. Solar caustics, critical curves, and Einstein rings are computed and discussed. Extremely high gravitational lens magnifications exist for observers situated so that an angularly small, unlensed source appears near a three-image caustic. Types of radiations that might undergo significant solar lens magnifications as they can traverse the core of the Sun, including neutrinos and gravitational radiation, are discussed.

Bijunath Patla; Robert J. Nemiroff

2007-11-29T23:59:59.000Z

12

Gravitational Lensing Characteristics of the Transparent Sun  

E-Print Network (OSTI)

The transparent Sun is modeled as a spherically symmetric and centrally condensed gravitational lens using recent Standard Solar Model (SSM) data. The Sun's minimum focal length is computed to a refined accuracy of 23.5 +/- 0.1 AU, just beyond the orbit of Uranus. The Sun creates a single image of a distant point source visible to observers inside this minimum focal length and to observers sufficiently removed from the line connecting the source through the Sun's center. Regions of space are mapped where three images of a distant point source are created, along with their associated magnifications. Solar caustics, critical curves, and Einstein rings are computed and discussed. Extremely high gravitational lens magnifications exist for observers situated so that an angularly small, unlensed source appears near a three-image caustic. Types of radiations that might undergo significant solar lens magnifications as they can traverse the core of the Sun, including neutrinos and gravitational radiation, are discusse...

Patla, Bijunath

2007-01-01T23:59:59.000Z

13

PROBING PRIMORDIAL NON-GAUSSIANITY WITH WEAK-LENSING MINKOWSKI FUNCTIONALS  

SciTech Connect

We study the cosmological information contained in the Minkowski functionals (MFs) of weak gravitational lensing convergence maps. We show that the MFs provide strong constraints on the local-type primordial non-Gaussianity parameter f {sub NL}. We run a set of cosmological N-body simulations and perform ray-tracing simulations of weak lensing to generate 100 independent convergence maps of a 25 deg{sup 2} field of view for f {sub NL} = -100, 0 and 100. We perform a Fisher analysis to study the degeneracy among other cosmological parameters such as the dark energy equation of state parameter w and the fluctuation amplitude {sigma}{sub 8}. We use fully nonlinear covariance matrices evaluated from 1000 ray-tracing simulations. For upcoming wide-field observations such as those from the Subaru Hyper Suprime-Cam survey with a proposed survey area of 1500 deg{sup 2}, the primordial non-Gaussianity can be constrained with a level of f {sub NL} {approx} 80 and w {approx} 0.036 by weak-lensing MFs. If simply scaled by the effective survey area, a 20,000 deg{sup 2} lensing survey using the Large Synoptic Survey Telescope will yield constraints of f {sub NL} {approx} 25 and w {approx} 0.013. We show that these constraints can be further improved by a tomographic method using source galaxies in multiple redshift bins.

Shirasaki, Masato; Yoshida, Naoki; Nishimichi, Takahiro [Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Hamana, Takashi, E-mail: masato.shirasaki@ipmu.jp [National Astronomical Observatory of Japan, Tokyo 181-0015 (Japan)

2012-11-20T23:59:59.000Z

14

Gravitational lensing in plasma: Relativistic images at homogeneous plasma  

E-Print Network (OSTI)

We investigate the influence of plasma presence on relativistic images formed by Schwarzschild black hole lensing. When a gravitating body is surrounded by a plasma, the lensing angle depends on a frequency of the electromagnetic wave due to refraction properties, and the dispersion properties of the light propagation in gravitational field in plasma. The last effect leads to difference, even in uniform plasma, of gravitational deflection angle in plasma from vacuum case. This angle depends on the photon frequency, what resembles the properties of the refractive prism spectrometer. Here we consider the case of a strong deflection angle for the light, traveling near the Schwarzschild black hole, surrounded by a uniform plasma. Asymptotic formulae are obtained for the case of a very large deflection angle, exceeding $2\\pi$. We apply these formulae for calculation of position and magnification of relativistic images in a homogeneous plasma, which are formed by the photons performing one or several revolutions around the central object. We conclude that the presence of the uniform plasma increases the angular size of relativistic rings or the angular separation of point images from the gravitating center. The presence of the uniform plasma increases also a magnification of relativistic images. The angular separation and the magnification become significantly larger than in the vacuum case, when the photon frequency goes to a plasma frequency.

Oleg Yu. Tsupko; Gennady S. Bisnovatyi-Kogan

2013-05-30T23:59:59.000Z

15

Effect of Correlated Noise on Source Shape Parameters and Weak Lensing Measurements  

E-Print Network (OSTI)

The measurement of shape parameters of sources in astronomical images is usually performed by assuming that the underlying noise is uncorrelated. Spatial noise correlation is however present in practice due to various observational effects and can affect source shape parameters. This effect is particularly important for measurements of weak gravitational lensing, for which the sought image distortions are typically of the order of only 1%. We compute the effect of correlated noise on two-dimensional gaussian fits in full generality. The noise properties are naturally quantified by the noise autocorrelation function (ACF), which is easily measured in practice. We compute the resulting bias on the mean, variance and covariance of the source parameters, and the induced correlation between the shapes of neighboring sources. We show that these biases are of second order in the inverse signal-to-noise ratio of the source, and could thus be overlooked if bright stars are used to monitor systematic distortions. Radio interferometric surveys are particularly prone to this effect because of the long-range pixel correlations produced by the Fourier inversion involved in their image construction. As a concrete application, we consider the search for weak lensing by large-scale structure with the FIRST radio survey. We measure the noise ACF for a FIRST coadded field, and compute the resulting ellipticity correlation function induced by the noise. In comparison with the weak-lensing signal expected in CDM models, the noise correlation effect is important on small angular scales, but is negligible for source separations greater than about 1 arcmin. We also discuss how noise correlation can affect weak-lensing studies with optical surveys.

A. Refregier; S. T. Brown

1998-03-24T23:59:59.000Z

16

EFFECTIVE MODELS FOR STATISTICAL STUDIES OF GALAXY-SCALE GRAVITATIONAL LENSING  

SciTech Connect

We have worked out simple analytical formulae that accurately approximate the relationship between the position of the source with respect to the lens center and the amplification of the images, hence the lens cross section, for realistic lens profiles. We find that, for essentially the full range of parameters either observationally determined or yielded by numerical simulations, the combination of dark matter and star distribution can be very well described, for lens radii relevant to strong lensing, by a simple power law whose slope is very weakly dependent on the parameters characterizing the global matter surface density profile and close to isothermal in agreement with direct estimates for individual lens galaxies. Our simple treatment allows an easy insight into the role of the different ingredients that determine the lens cross section and the distribution of gravitational amplifications. They also ease the reconstruction of the lens mass distribution from the observed images and, vice versa, allow a fast application of ray-tracing techniques to model the effect of lensing on a variety of source structures. The maximum amplification depends primarily on the source size. Amplifications larger than Almost-Equal-To 20 are indicative of compact source sizes at high-z, in agreement with expectations if galaxies formed most of their stars during the dissipative collapse of cold gas. Our formalism has allowed us to reproduce the counts of strongly lensed galaxies found in the H-ATLAS Science Demonstration Phase field. While our analysis is focused on spherical lenses, we also discuss the effect of ellipticity and the case of late-type lenses (showing why they are much less common, even though late-type galaxies are more numerous). Furthermore, we discuss the effect of a cluster halo surrounding the early-type lens and of a supermassive black hole at its center.

Lapi, A. [Dipartimento Fisica, Universita 'Tor Vergata', Via Ricerca Scientifica 1, 00133 Roma (Italy); Negrello, M. [INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova (Italy); Gonzalez-Nuevo, J.; Cai, Z.-Y.; De Zotti, G.; Danese, L. [Astrophysics Sector, SISSA, Via Bonomea 265, 34136 Trieste (Italy)

2012-08-10T23:59:59.000Z

17

Weak lensing and the Dyer-Roeder approximation  

E-Print Network (OSTI)

The distance-redshift relation plays an important role in cosmology. In the standard approach to cosmology it is assumed that this relation is the same as in the homogeneous universe. As the real universe is not homogeneous there are several methods to calculate the correction. The weak lensing approximation and the Dyer-Roeder relation are one of them. This paper establishes a link between these two approximations. It is shown that if the universe is homogeneous with only small, vanishing after averaging, density fluctuations along the line of sight, then the distance correction is negligible. It is also shown that a vanishing 3D average of density fluctuations does not imply that the mean of density fluctuations along the line of sight is zero. In this case, even within the linear approximation, the distance correction is not negligible. The modified version of the Dyer-Roeder relation is presented and it is shown that this modified relation is consistent with the correction obtained within the weak lensing approximation. The correction to the distance for a source at z ~ 2 is of order of a few percent. Thus, with an increasing precision of cosmological observations an accurate estimation of the distance is essential. Otherwise errors due to miscalculation the distance can become a major source of systematics.

Krzysztof Bolejko

2010-11-17T23:59:59.000Z

18

OBSERVING GRAVITATIONAL LENSING EFFECTS BY Sgr A* WITH GRAVITY  

SciTech Connect

The massive black hole Sgr A* at the Galactic center is surrounded by a cluster of stars orbiting around it. Light from these stars is bent by the gravitational field of the black hole, giving rise to several phenomena: astrometric displacement of the primary image, the creation of a secondary image that may shift the centroid of Sgr A*, and magnification effects on both images. The soon-to-be second-generation Very Large Telescope Interferometer instrument GRAVITY will perform observations in the near-infrared of the Galactic center at unprecedented resolution, opening the possibility of observing such effects. Here we investigate the observability limits for GRAVITY of gravitational lensing effects on the S-stars in the parameter space 1[D{sub LS}, {gamma}, K], where D{sub LS} is the distance between the lens and the source, {gamma} is the alignment angle of the source, and K is the source's apparent magnitude in the K band. The easiest effect to observe in future years is the astrometric displacement of primary images. In particular, the shift of the star S17 from its Keplerian orbit will be detected as soon as GRAVITY becomes operative. For exceptional configurations, it will be possible to detect effects related to the spin of the black hole or post-Newtonian orders in the deflection.

Bozza, V. [Department of Physics 'E.R. Caianiello', University of Salerno, Via Ponte Don Melillo, Fisciano I-84084 (Italy); Mancini, L., E-mail: valboz@physics.unisa.it, E-mail: mancini@mpia-hd.mpg.de [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)

2012-07-01T23:59:59.000Z

19

Characterizing Lenses and Lensed Stars of High-Magnification Gravitational Microlensing Events With Lenses Passing Over Source Stars  

E-Print Network (OSTI)

We present the analysis of the light curves of 9 high-magnification gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For 8 events, we measure the Einstein radii and the lens-source relative proper motions. Among them, 6 events (OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2011-BLG-093, MOA-2011-BLG-274, and OGLE-2011-BLG-0990/MOA-2011-BLG-300) are found to have Einstein radii less than 0.2 mas, making the lenses candidates of very low-mass stars or brown dwarfs. For MOA-2011-BLG-274, especially, the small Einstein ...

Choi, J -Y; Park, S -Y; Han, C; Gould, A; Sumi, T; Udalski, A; Beaulieu, J -P; Street, R; Dominik, M; Allen, W; Bos, M; Christie, G W; Depoy, D L; Dong, S; Drummond, J; Gal-Yam, A; Gaudi, B S; Henderson, C B; Hung, L -W; Janczak, J; Lee, C -U; Mallia, F; Maury, A; McCormick, J; McGregor, D; Monard, L A G; Moorhouse, D; Muńoz, J A; Natusch, T; Nelson, C; Park, B -G; Pogge, R W; Tan, T -G "TG"; Thornley, G; Yee, J C; Abe, F; Barnard, E; Baudry, J; Bennett, D P; Bond, I A; Botzler, C S; Freeman, M; Fukui, A; Furusawa, K; Hayashi, F; Hearnshaw, J B; Hosaka, S; Itow, Y; Kamiya, K; Kilmartin, P M; Kobara, S; Korpela, A; Lin, W; Ling, C H; Makita, S; Masuda, K; Matsubara, Y; Miyake, N; Muraki, Y; Nagaya, M; Nishimoto, K; Ohnishi, K; Okumura, T; Omori, K; Perrott, Y C; Rattenbury, N; Saito, To; Skuljan, L; Sullivan, D J; Suzuki, D; Suzuki, K; Sweatman, W L; Takino, S; Tristram, P J; Wada, K; Yock, P C M; Szyma?ski, M K; Kubiak, M; Pietrzy?ski, G; Soszy?ski, I; Poleski, R; Ulaczyk, K; Wyrzykowski, ?; Koz?owski, S; Pietrukowicz, P; Albrow, M D; Bachelett, E; Batista, V; Bennett, C; Bowens-Rubin, R; Brillant, S; Cassan, A; Cole, A; Corrales, E; Coutures, Ch; Dieters, S; Prester, D Dominis; Donatowicz, J; Fouqué, P; Greenhill, J; Kane, S R; Menzies, J; Sahu, K C; Wambsganss, J; Williams, A; Zub, M; Allan, A; Bramich, D M; Browne, P; Clay, N; Fraser, S; Horne, K; Kains, N; Mottram, C; Snodgrass, C; Steele, I; Tsapras, Y; Alsubai, K A; Bozza, V; Burgdorf, M J; Novati, S Calchi; Dodds, P; Dreizler, S; Finet, F; Gerner, T; Glitrup, M; Grundahl, F; Hardis, S; Harpsře, K; Hinse, T C; Hundertmark, M; Jřrgensen, U G; Kerins, E; Liebig, C; Maier, G; Mancini, L; Mathiasen, M; Penny, M T; Proft, S; Rahvar, S; Ricci, D; Scarpetta, G; Schäfer, S; Schönebeck, F; Skottfelt, J; Surdej, J; Southworth, J; Zimmer, F

2011-01-01T23:59:59.000Z

20

Feasibility of Probing Dark Energy with Strong Gravitational Lensing Systems -- Fisher-Matrix Approach --  

E-Print Network (OSTI)

We assess the feasibility of probing dark energy with strong gravitational lensing systems. The capability of the method, which depends on the accuracy with which the lensing systems are modeled, is quantitatively investigated using the Fisher-matrix formalism. We show that this method might place useful constraints on the density parameter and the redshift evolution of the dark energy by combining it with a constraint from supernova measurements. For this purpose, the lens potential needs to be precisely reconstructed. We determine the required quality of data. We also briefly discuss the optimal strategy to constrain the cosmological parameters using gravitational lensing systems.

Kazuhiro Yamamoto; Yasufum Kadoya; Tsukasa Murata; Toshifumi Futamase

2001-10-29T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

An Analysis of DES Cluster Simulations through the IMCAT and Shapelets Weak Lensing Pipelines  

E-Print Network (OSTI)

We have run two completely independent weak lensing analysis pipelines on a set of realistic simulated images of a massive galaxy cluster with a singular isothermal sphere profile (galaxy velocity dispersion sigma_v=1250 km/ sec). The suite of images was constructed using the simulation tools developed by the Dark Energy Survey. We find that both weak lensing pipelines can accurately recover the velocity dispersion of our simulated clusters, suggesting that current weak lensing tools are accurate enough for measuring the shear profile of massive clusters in upcoming large photometric surveys. We also demonstrate how choices of some cuts influence the final shear profile and sigma_v measurement. Analogously to the STEP program, we make all of these cluster simulation images publically available for other groups to analyze through their own weak lensing pipelines.

Gill, M S S; Draskovic, J P; Honscheid, K; Lin, H; Kuropatkin, N; Martini, P; Peeples, M; Rozo, E; Smith, G N; Weinberg, D H

2009-01-01T23:59:59.000Z

22

Gravitational Interaction of Higgs Boson and Weak Boson Scattering  

E-Print Network (OSTI)

With the LHC discovery of a 125 GeV Higgs-like boson, we study gravitational interaction of the Higgs boson via the unique dimension-4 operator involving Higgs doublet and scalar curvature, $\\,\\xi H^\\dag H R\\,$, with nonminimal coupling $\\,\\xi\\,$. This Higgs portal term can be transformed away in Einstein frame and induces gauge-invariant effective interactions in the Higgs sector. We study the weak boson scattering in Einstein frame, and explicitly demonstrate the longitudinal-Goldstone boson equivalence theorem in the presence of $\\,\\xi\\,$ coupling. With these, we derive unitarity bound on the Higgs gravitational coupling $\\,\\xi\\,$ in Einstein frame, which is stronger than that inferred from the current LHC Higgs measurements. We further study $\\xi$-dependent weak boson scattering cross sections at TeV scale, and propose a new LHC probe of the Higgs-gravity coupling $\\,\\xi\\,$ via weak boson scattering experiments.

Zhong-Zhi Xianyu; Jing Ren; Hong-Jian He

2013-05-01T23:59:59.000Z

23

INTERPOLATING MASKED WEAK-LENSING SIGNAL WITH KARHUNEN-LOEVE ANALYSIS  

SciTech Connect

We explore the utility of Karhunen-Loeve (KL) analysis in solving practical problems in the analysis of gravitational shear surveys. Shear catalogs from large-field weak-lensing surveys will be subject to many systematic limitations, notably incomplete coverage and pixel-level masking due to foreground sources. We develop a method to use two-dimensional KL eigenmodes of shear to interpolate noisy shear measurements across masked regions. We explore the results of this method with simulated shear catalogs, using statistics of high-convergence regions in the resulting map. We find that the KL procedure not only minimizes the bias due to masked regions in the field, it also reduces spurious peak counts from shape noise by a factor of {approx}3 in the cosmologically sensitive regime. This indicates that KL reconstructions of masked shear are not only useful for creating robust convergence maps from masked shear catalogs, but also offer promise of improved parameter constraints within studies of shear peak statistics.

VanderPlas, J. T.; Connolly, A. J. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Jain, B.; Jarvis, M. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104-6396 (United States)

2012-01-10T23:59:59.000Z

24

SDSSJ102111.02+491330.4: A Newly Discovered Gravitationally Lensed Quasar  

E-Print Network (OSTI)

We report follow-up observations of two gravitational lens candidates identified in the Sloan Digital Sky Survey (SDSS) dataset. We have confirmed that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed quasar. This lens system exhibits two images of a $z = 1.72$ quasar, with an image separation of $1{\\farcs}14 \\pm 0.04$. Optical and near-IR imaging of the system reveals the presence of the lensing galaxy between the two quasar images. Observations of SDSS J112012.12+671116.0 indicate that it is more likely a binary quasar than a gravitational lens. This system has two quasars at a redshift of $z = 1.49$, with an angular separation of $1{\\farcs}49 \\pm 0.02$. However, the two quasars have markedly different SEDs and no lens galaxy is apparent in optical and near-IR images of this system. We also present a list of 31 SDSS lens candidates which follow-up observations have confirmed are \\textit{not} gravitational lenses.

Pindor, B; Gregg, M D; Becker, R H; Inada, N; Oguri, M; Hall, P B; Johnston, D E; Richards, G T; Schneider, D P; Turner, E L; Brasi, G; Hinz, P M; Kenworthy, M A; Miller, D; Barentine, J C; Brewington, H J; Brinkmann, J; Harvanek, M; Kleinman, S J; Krzesínski, J; Long, D; Neilsen, E H; Newman, P R; Nitta, A; Snedden, S A; York, D G; Pindor, Bart; Eisenstein, Daniel J.; Gregg, Michael D.; Becker, Robert H.; Inada, Naohisa; Oguri, Masamune; Hall, Patrick B.; Johnston, David E.; Richards, Gordon T.; Schneider, Donald P.; Turner, Edwin L.; Brasi, Guido; Hinz, Philip M.; Kenworthy, Matthew A.; Miller, Doug; Brewington, Howard J.; Harvanek, Michael; Krzesinski, Jurek; Long, Dan; Neilsen, Eric H.; Newman, Peter R.; Nitta, Atsuko; Snedden, Stephanie A.; York, Donald G.

2006-01-01T23:59:59.000Z

25

SDSSJ102111.02+491330.4: A Newly Discovered Gravitationally Lensed Quasar  

Science Conference Proceedings (OSTI)

We report follow-up observations of two gravitational lens candidates identified in the Sloan Digital Sky Survey (SDSS) dataset. We have confirmed that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed quasar. This lens system exhibits two images of a z = 1.72 quasar, with an image separation of 1''.14 {+-} 0.04. Optical and near-IR imaging of the system reveals the presence of the lensing galaxy between the two quasar images. Observations of SDSS J112012.12+671116.0 indicate that it is more likely a binary quasar than a gravitational lens. This system has two quasars at a redshift of z = 1.49, with an angular separation of 1''.49 {+-} 0.02. However, the two quasars have markedly different SEDs and no lens galaxy is apparent in optical and near-IR images of this system. We also present a list of 31 SDSS lens candidates which follow-up observations have confirmed are not gravitational lenses.

Pindor, B; Eisenstein, D J; Gregg, M D; Becker, R H; Inada, N; Oguri, M; Hall, P B; Johnston, D E; Richards, G T; Schneider, D P; Turner, E L; Brasi, G; Hinz, P M; Kenworthy, M A; Miller, D; Barentine, J C; Brewington, H J; Brinkmann, J; Harvanek, M; Kleinman, S J; Krzesinski, J; Long, D; Neilsen Jr., E H; Newman, P R; Nitta, A; Snedden, S A; York, D G

2005-11-10T23:59:59.000Z

26

SDSSJ102111.02+491330.4: A Newly Discovered Gravitationally Lensed Quasar  

E-Print Network (OSTI)

We report follow-up observations of two gravitational lens candidates identified in the Sloan Digital Sky Survey (SDSS) dataset. We have confirmed that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed quasar. This lens system exhibits two images of a $z = 1.72$ quasar, with an image separation of $1{\\farcs}14 \\pm 0.04$. Optical and near-IR imaging of the system reveals the presence of the lensing galaxy between the two quasar images. Observations of SDSS J112012.12+671116.0 indicate that it is more likely a binary quasar than a gravitational lens. This system has two quasars at a redshift of $z = 1.49$, with an angular separation of $1{\\farcs}49 \\pm 0.02$. However, the two quasars have markedly different SEDs and no lens galaxy is apparent in optical and near-IR images of this system. We also present a list of 31 SDSS lens candidates which follow-up observations have confirmed are \\textit{not} gravitational lenses.

Bart Pindor; Daniel J. Eisenstein; Michael D. Gregg; Robert H. Becker; Naohisa Inada; Masamune Oguri; Patrick B. Hall; David E. Johnston; Gordon T. Richards; Donald P. Schneider; Edwin L. Turner; Guido Brasi; Philip M. Hinz; Matthew A. Kenworthy; Doug Miller; J. C. Barentine; Howard J. Brewington; J. Brinkmann; Michael Harvanek; S. J. Kleinman; Jurek Krzesinski; Dan Long; Eric H. Neilsen, Jr.; Peter R. Newman; Atsuko Nitta; Stephanie A. Snedden; Donald G. York

2005-09-12T23:59:59.000Z

27

SDSS J102111.02+491330.4: A Newly discovered gravitationally lensed quasar  

Science Conference Proceedings (OSTI)

We report follow-up observations of two gravitational lens candidates identified in the Sloan Digital Sky Survey (SDSS) dataset. We have confirmed that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed quasar. This lens system exhibits two images of a z = 1.72 quasar, with an image separation of 1.14'' {+-} 0.04''. Optical and near-IR imaging of the system reveals the presence of the lensing galaxy between the two quasar images. Observations of SDSS J112012.12+671116.0 indicate that it is more likely a binary quasar than a gravitational lens. This system has two quasars at a redshift of z = 1.49, with an angular separation of 1.49'' {+-} 0.02''. However, the two quasars have markedly different SEDs and no lens galaxy is apparent in optical and near-IR images of this system. We also present a list of 31 SDSS lens candidates which follow-up observations have confirmed are not gravitational lenses.

Pindor, Bart; Eisenstein, Daniel J.; Gregg, Michael D.; Becker, Robert H.; Inada, Naohisa; Oguri, Masamune; Hall, Patrick B.; Johnston, David E.; Richards, Gordon T.; Schneider, Donald P.; Turner, Edwin L.; Brasi, Guido; Hinz, Philip M.; Kenworthy, Matthew A.; Miller, Doug; Barentine, J.C.; Brewington, Howard J.; Brinkmann, J.; Harvanek, Michael; Kleinman, S.J.; Krzesinski, Jurek; /Toronto U., Astron. Dept. /Arizona U., Astron. Dept. - Steward Observ. /UC, Davis /LLNL, Livermore /Tokyo U., Inst. Astron. /Tokyo U. /Princeton U. Observ. /York U., Canada /Penn State U., Astron. Astrophys. /Apache Point Observ. /Mt. Suhora Observ., Cracow /Fermilab /Chicago U., Astron. Astrophys. Ctr.

2005-09-01T23:59:59.000Z

28

Complementarity of weak lensing and peculiar velocity measurements in testing general relativity  

SciTech Connect

We explore the complementarity of weak lensing and galaxy peculiar velocity measurements to better constrain modifications to General Relativity. We find no evidence for deviations from General Relativity on cosmological scales from a combination of peculiar velocity measurements (for Luminous Red Galaxies in the Sloan Digital Sky Survey) with weak lensing measurements (from the Canadian France Hawaii Telescope Legacy Survey). We provide a Fisher error forecast for a Euclid-like space-based survey including both lensing and peculiar velocity measurements and show that the expected constraints on modified gravity will be at least an order of magnitude better than with present data, i.e. we will obtain {approx_equal}5% errors on the modified gravity parametrization described here. We also present a model-independent method for constraining modified gravity parameters using tomographic peculiar velocity information, and apply this methodology to the present data set.

Song, Yong-Seon [Korea Institute for Advanced Study, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom); Zhao Gongbo; Bacon, David; Koyama, Kazuya; Nichol, Robert C. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom); Pogosian, Levon [Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6 (Canada)

2011-10-15T23:59:59.000Z

29

Extrinsic Radio Variability of JVAS/CLASS Gravitational Lenses  

E-Print Network (OSTI)

We present flux-ratio curves of the fold and cusp (i.e. close multiple) images of six JVAS/CLASS gravitational lens systems. The data were obtained over a period of 8.5 months in 2001 with the Multi-Element Radio-Linked Interferometer Network (MERLIN) at 5-GHz with 50 mas resolution, as part of a MERLIN Key-Project. Even though the time delays between the fold and cusp images are small (<~1 day) compared to the time-scale of intrinsic source variability, all six lens systems show evidence that suggests the presence of extrinsic variability. In particular, the cusp images of B2045+265 -- regarded as the strongest case of the violation of the cusp relation (i.e. the sum of the magnifications of the three cusp images add to zero) -- show extrinsic variations in their flux-ratios up to ~40 percent peak-to-peak on time scales of several months. Its low Galactic latitude of b=-10 degree and a line-of-sight toward the Cygnus superbubble region suggest that Galactic scintillation is the most likely cause. The cusp images of B1422+231 at b=+69 degree do not show strong extrinsic variability. Galactic scintillation can therefore cause significant scatter in the cusp and fold relations of some radio lens systems (up to 10 percent rms), even though these relations remain violated when averaged over a <~1 year time baseline.

L. V. E. Koopmans; A. Biggs; R. D. Blandford; I. W. A. Browne; N. J. Jackson; S. Mao; P. N. Wilkinson; A. G. de Bruyn; J. Wambsganss

2003-02-11T23:59:59.000Z

30

Subaru weak-lensing study of A2163: bimodal mass structure  

E-Print Network (OSTI)

We present a weak-lensing analysis of the merging cluster A2163 using Subaru/Suprime-Cam and CHFT/Mega-Cam data and discuss the dynamics of this cluster merger, based on complementary weak-lensing, X-ray, and optical spectroscopic datasets. From two dimensional multi-component weak-lensing analysis, we reveal that the cluster mass distribution is well described by three main components: a two component main cluster A2163-A with mass ratio 1:8, and its cluster satellite A2163-B. The bimodal mass distribution in A2163-A is similar to the galaxy density distribution, but appears as spatially segregated from the brightest X-ray emitting gas region. We discuss the possible origins of this gas-dark matter offset, and suggest the gas core of the A2163-A subcluster to have been stripped away by ram pressure from its dark matter component. The survival of this gas core to the tidal forces exerted by the main cluster let us infer a subcluster accretion with non-zero impact parameter. Dominated by the most massive compo...

Okabe, Nobuhiro; Mazzotta, Pasquale; Maurogordato, Sophie

2011-01-01T23:59:59.000Z

31

A WEAK-LENSING AND NEAR-INFRARED STUDY OF A3192: DISASSEMBLING A RICHNESS CLASS 3 ABELL CLUSTER  

SciTech Connect

We present a joint gravitational lensing and near-infrared study of the galaxy cluster Abell 3192 (A3192) that has been associated both with galaxies at z = 0.168 and with the X-ray luminous cluster RXC J0358.8-2955 (RXC J0358) at z = 0.425. Weak-lensing analysis of our Hubble Space Telescope snapshot observation with the Advanced Camera for Surveys detects two mass over-densities separated by {approx}2 arcmin, one adjacent to the optical position of A3192 (4.4{sigma} significance) and the other adjacent to the X-ray position of RXC J0358 (6.2{sigma} significance). These mass peaks coincide with peaks in the K-band luminosity density of galaxies with near-infrared colors consistent with the red sequence at z = 0.168 and z 0.425, respectively. Moreover, the Bayesian evidence of parameterized mass models that include two cluster/group-scale halos centered on the respective mass peaks exceeds that of single-halo models by a factor of {>=}10. The total projected mass of each galaxy system within 250 kpc of the respective peaks is M{sub WL}(z = 0.168) {approx_equal} 3 Multiplication-Sign 10{sup 13} M{sub Sun} and M{sub WL}(z = 0.425) {approx_equal} 1.2 Multiplication-Sign 10{sup 14} M{sub Sun }, both with total mass-to-light ratios of M{sub WL}/L{sub K} {approx_equal} 20 M{sub Sun }/L{sub Sun }. The original Abell cluster therefore comprises two independent galaxy systems-a foreground group at z = 0.168 and RXC J0358 at z = 0.425. Our results demonstrate the power of combining X-ray, near-infrared, and weak-lensing observations to select massive clusters, place those clusters and interloper galaxy systems along the line of sight, and measure their masses. This combination will be invaluable to robust interpretation of future high-redshift cluster surveys, including eROSITA.

Hamilton-Morris, Victoria; Smith, Graham P.; Haines, C. P.; Sanderson, A. J. R. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Edge, A. C. [Institute of Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Egami, E. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Marshall, P. J. [Sub-department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Targett, T. A., E-mail: vhh@star.sr.bham.ac.uk, E-mail: gps@star.sr.bham.ac.uk [SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)

2012-04-01T23:59:59.000Z

32

Bayesian analysis of joint strong gravitational lensing and dynamic galactic mass in SLACS: evidence of line-of-sight contamination  

E-Print Network (OSTI)

We readdress the calculation of the mass of early-type galaxies using strong gravitational lensing and stellar dynamics. Our sample comprises 27 galaxies in the Sloan Lens ACS (SLACS) Survey. Comparing the mass estimates from these two independent methods in a Bayesian framework, we find evidence of significant line-of-sight mass contamination. Assuming a power-law mass distribution, the best fit density profile is given by $\\rho \\propto r^{-1.69\\pm0.05}$. We show that neglecting the line-of-sight mass contamination produces an overestimate of the mass attributed to the lens-galaxy by the lensing method, which introduces a bias in favor of a SIS profile when using the joint lensing and dynamic analysis to determine the slope of the density profile. We suggest that the line-of-sight contamination could also be important for other astrophysical and cosmological uses of joint lensing and dynamical measurements.

Antonio C. C. Guimarăes; Laerte Sodré Jr.

2007-06-21T23:59:59.000Z

33

Weak-Lensing Detection at z~1.3: Measurement of the Two Lynx Clusters with Advanced Camera for Surveys  

E-Print Network (OSTI)

(Abridged) We present a HST/ACS weak-lensing study of RX J0849+4452 and RX J0848+4453, the two most distant (at z=1.26 and z=1.27, respectively) clusters yet measured with weak-lensing. The two clusters are separated by ~4' from each other and appear to form a supercluster in the Lynx field. Using our deep ACS F775W and F850LP imaging, we detected weak-lensing signals around both clusters at ~4 sigma levels. The mass distribution indicated by the reconstruction map is in good spatial agreement with the cluster galaxies. From the SIS fitting, we determined that RX J0849+4452 and RX J0848+4453 have similar projected masses of ~2.0x10^14 solar mass and ~2.1x10^14 solar mass, respectively, within a 0.5 Mpc (~60") aperture radius.

Jee, M J; Ford, H C; Holden, B; Illingworth, G D; Mei, S; White, R L

2006-01-01T23:59:59.000Z

34

Weak-Lensing Detection at z~1.3: Measurement of the Two Lynx Clusters with Advanced Camera for Surveys  

E-Print Network (OSTI)

(Abridged) We present a HST/ACS weak-lensing study of RX J0849+4452 and RX J0848+4453, the two most distant (at z=1.26 and z=1.27, respectively) clusters yet measured with weak-lensing. The two clusters are separated by ~4' from each other and appear to form a supercluster in the Lynx field. Using our deep ACS F775W and F850LP imaging, we detected weak-lensing signals around both clusters at ~4 sigma levels. The mass distribution indicated by the reconstruction map is in good spatial agreement with the cluster galaxies. From the SIS fitting, we determined that RX J0849+4452 and RX J0848+4453 have similar projected masses of ~2.0x10^14 solar mass and ~2.1x10^14 solar mass, respectively, within a 0.5 Mpc (~60") aperture radius.

M. J. Jee; R. L. White; H. C. Ford; G. D. Illingworth; J. P. Blakeslee; B. Holden; S. Mei

2006-01-16T23:59:59.000Z

35

SUBARU WEAK-LENSING STUDY OF A2163: BIMODAL MASS STRUCTURE  

Science Conference Proceedings (OSTI)

We present a weak-lensing analysis of the merging cluster A2163 using Subaru/Suprime-Cam and CFHT/Mega-Cam data and discuss the dynamics of this cluster merger, based on complementary weak-lensing, X-ray, and optical spectroscopic data sets. From two-dimensional multi-component weak-lensing analysis, we reveal that the cluster mass distribution is well described by three main components including the two-component main cluster A2163-A with mass ratio 1:8, and its cluster satellite A2163-B. The bimodal mass distribution in A2163-A is similar to the galaxy density distribution, but appears as spatially segregated from the brightest X-ray emitting gas region. We discuss the possible origins of this gas-dark-matter offset and suggest the gas core of the A2163-A subcluster has been stripped away by ram pressure from its dark matter component. The survival of this gas core from the tidal forces exerted by the main cluster lets us infer a subcluster accretion with a non-zero impact parameter. Dominated by the most massive component of A2163-A, the mass distribution of A2163 is well described by a universal Navarro-Frenk-White profile as shown by a one-dimensional tangential shear analysis, while the singular-isothermal sphere profile is strongly ruled out. Comparing this cluster mass profile with profiles derived assuming intracluster medium hydrostatic equilibrium (H.E.) in two opposite regions of the cluster atmosphere has allowed us to confirm the prediction of a departure from H.E. in the eastern cluster side, presumably due to shock heating. Yielding a cluster mass estimate of M{sub 500} = 11.18{sup +1.64}{sub -1.46} Multiplication-Sign 10{sup 14} h {sup -1} M{sub Sun }, our mass profile confirms the exceptionally high mass of A2163, consistent with previous analyses relying on the cluster dynamical analysis and Y{sub X} mass proxy.

Okabe, N. [Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China); Bourdin, H.; Mazzotta, P. [Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Roma (Italy); Maurogordato, S., E-mail: okabe@asiaa.sinica.edu.tw [Universite de Nice Sophia-Antipolis, CNRS, Laboratoire Cassiopee, CNRS, UMR 6202, Observatoire de la Cote d' Azur, BP4229, 06304 Nice Cedex 4 (France)

2011-11-10T23:59:59.000Z

36

Real space estimator for the weak lensing convergence from the CMB  

E-Print Network (OSTI)

We propose an estimator defined in real space for the reconstruction of the weak lensing potential due to the intervening large scale structure from high resolution maps of the cosmic microwave background. This estimator was motivated as an alternative to the quadratic estimator in harmonic space to surpass the difficulties of the analysis of maps containing galactic cuts and point source excisions. Using maps synthesised by pixel remapping, we implement the estimator for two experiments, namely one in the absence and one in the presence of detector noise, and compare the reconstruction of the convergence field with that obtained with the quadratic estimator defined in harmonic space. We find good agreement between the input and the reconstructed power spectra using the proposed real space estimator. We discuss interesting features of the real space estimator and future extensions of this work.

Carvalho, C S

2010-01-01T23:59:59.000Z

37

TESTING GRAVITATIONAL LENSING AS THE SOURCE OF ENHANCED STRONG Mg II ABSORPTION TOWARD GAMMA-RAY BURSTS  

Science Conference Proceedings (OSTI)

Sixty percent of gamma-ray bursts (GRBs) reveal strong Mg II absorbing systems, which is a factor of {approx}2 times the rate seen along lines of sight to quasars. Previous studies argue that the discrepancy in the strong Mg II covering factor is most likely to be the result of either quasars being obscured due to dust or the consequence of many GRBs being strongly gravitationally lensed. We analyze observations of quasars that show strong foreground Mg II absorption. We find that GRB lines of sight pass closer to bright galaxies than would be expected for random lines of sight within the impact parameter expected for strong Mg II absorption. While this cannot be explained by obscuration in the GRB sample, it is a natural consequence of gravitational lensing. Upon examining the particular configurations of galaxies near a sample of GRBs with strong Mg II absorption, we find several intriguing lensing candidates. Our results suggest that lensing provides a viable contribution to the observed enhancement of strong Mg II absorption along lines of sight to GRBs, and we outline the future observations required to test this hypothesis conclusively.

Rapoport, Sharon; Onken, Christopher A.; Schmidt, Brian P.; Tucker, Brad E. [Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia); Wyithe, J. Stuart B. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Levan, Andrew J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2012-08-01T23:59:59.000Z

38

Primordial production of massive relic gravitational waves from a weak modification of General Relativity  

E-Print Network (OSTI)

The production of a stochastic background of relic gravitational waves is well known in various works in the literature, where, using the so called adiabatically-amplified zero-point fluctuations process it has been shown how the standard inflationary scenario for the early universe can in principle provide a distinctive spectrum of relic gravitational waves. In this paper, it is shown that a weak modification of General Relativity produces a third massive polarization of gravitational waves and the primordial production of this polarization is analysed adapting the adiabatically-amplified zero-point fluctuations process at this case. The presence of the mass could also have important applications in cosmology as the fact that gravitational waves can have mass could give a contribution to the dark matter of the Universe. At the end of the paper an upper bound for these relic gravitational waves, which arises from the WMAP constrains, is also released.

Christian Corda

2008-12-02T23:59:59.000Z

39

Weak lensing mass map and peak statistics in CFHT/Stripe82 survey  

E-Print Network (OSTI)

We present the weak lensing mass map of the 173 tiles Canada-France-Hawaii Telescope Stripe82 Survey (CS82) with the effective area ~124 square degrees and study the peak statistics, including peak abundance, correlation functions and tangential-shear profile of peaks with the mass map. We find that (1) peak abundance detected in CS82 are consistent with predictions from a Lambda-CDM cosmological model, once noise effects are properly included; (2) correlation function of peaks with different signal-to-noise ratio (SNR) can be well fitted with power laws. Combining with the SDSS-III/Constant Mass (CMASS) galaxies, the cross-correlation between CMASS galaxies and high SNR peaks can be well-fitted with a power law; (3) the tangential shear profiles of the peaks increase with SNR. We concentrate on fitting spherical models to the tangential profiles with both singular isothermal sphere (SIS) and Navarro Frenk & White (NFW) models. For the high SNR peaks, the SIS model is rejected at ~3-sigma. Comparing the D...

Shan, HuanYuan; Comparat, Johan; Jullo, Eric; Charbonnier, Aldee; Erben, Thomas; Makler, Martin; Moraes, Bruno; Van Waerbeke, Ludovic; Courbin, Frederic; Meylan, George; Tao, Charling; Taylor, James E

2013-01-01T23:59:59.000Z

40

Proving the conservation of surface brightness during the strong and weak lensing of light by an isothermal sphere  

E-Print Network (OSTI)

An analytical proof of the conservation of surface brightness during the strong and weak lensing of light by a singular isothermal sphere is provided. It is shown that the movement of asymptotic rays provide room for precisely the extra solid angle claimed by the magnification of the centrally passing rays. Previous claim of a violation of this conservation law, leading to a problem over the COBE all sky CMB flux, is hereby withdrawn.

Richard Lieu

2004-09-27T23:59:59.000Z

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41

Fluctuations in the Gravitational, Strong and Weak Nuclear Fields through an Effective Harmonic Oscillator Model  

E-Print Network (OSTI)

We propose an effective harmonic oscillator model in order to treat the fluctuations of the gravitational, strong and weak nuclear fields. With respect to the gravitational field, first we use the model to estimate its fluctuating strength, necessary to decohere the wavefunction of a cubic centimeter of air at the standard temperature and pressure conditions. Second, the fluctuation of a point mass through a distance equal to the Planck length leads to the self-gravitational interaction of a particle, which can be related to its de Broglie frequency. Third, by making the equality of the fluctuating field strength with the gravitational field of a mass M at half of its Schwarzschild radius, we obtain an estimate of the mass of the Universe. We also consider the fluctuations of the strong nuclear field, as a means to estimate the separation in energy between the ground state and the centroid of the excitated states of the nucleon. Finally, taking into account the neutron-proton mass difference, we use the fluctuations of the weak nuclear field in order to evaluate the weak coupling constant.

P. R. Silva

2001-12-10T23:59:59.000Z

42

Gravitation  

NLE Websites -- All DOE Office Websites (Extended Search)

Gravity Was hlt sie zusammen? Gravitation Und wo bleibt die Gravitation? Gravitation ist eine schwierige Sache. Sie gehrt sicher zu den fundamentalen Wechselwirkungen, aber das...

43

3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847  

SciTech Connect

We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O III] {lambda}5007 and H{beta} emission lines with rest-frame equivalent widths of 2000 {+-} 100 and 520 {+-} 40 A, respectively. The source has a stellar mass {approx}10{sup 8} M{sub Sun }, sSFR {approx} 100 Gyr{sup -1}, and detection of [O III] {lambda}4363 yields a metallicity of 12 + log (O/H) = 7.5 {+-} 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size r{sub e} {approx}300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey.

Brammer, Gabriel B.; Sanchez-Janssen, Ruben [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Labbe, Ivo; Franx, Marijn; Fumagalli, Mattia; Patel, Shannon [Leiden Observatory, Leiden University, 2300-RA Leiden (Netherlands); Da Cunha, Elisabete; Rix, Hans-Walter; Schmidt, Kasper B.; Van der Wel, Arjen [Max Planck Institute for Astronomy (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany); Erb, Dawn K. [Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States); Lundgren, Britt; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Van Dokkum, Pieter G.; Wake, David A.; Whitaker, Katherine E. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Marchesini, Danilo [Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States); Quadri, Ryan, E-mail: gbrammer@eso.org [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2012-10-10T23:59:59.000Z

44

Geometrical approach to strong gravitational lensing in f(R) gravity  

Science Conference Proceedings (OSTI)

We present a framework for the study of lensing in spherically symmetric spacetimes within the context of f(R) gravity. Equations for the propagation of null geodesics, together with an expression for the bending angle, are derived for any f(R) theory and then applied to an exact spherically symmetric solution of R{sup n} gravity. We find that for this case more bending is expected for R{sup n} gravity theories in comparison to general relativity and is dependent on the value of n and the value of the distance of closest approach of the incident null geodesic.

Nzioki, Anne Marie; Goswami, Rituparno [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, 7701 (South Africa); Dunsby, Peter K. S. [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, 7701 (South Africa); South African Astronomical Observatory, Observatory, Cape Town (South Africa); Carloni, Sante [Institut d'Estudis Espacials de Catalunya (IEEC), Campus UAB, Facultat Ciencies, Torre C5-Par-2a pl, E-08193 Bellaterra (Barcelona) (Spain)

2011-01-15T23:59:59.000Z

45

ON DARK PEAKS AND MISSING MASS: A WEAK-LENSING MASS RECONSTRUCTION OF THE MERGING CLUSTER SYSTEM A520 ,  

SciTech Connect

Merging clusters of galaxies are unique in their power to directly probe and place limits on the self-interaction cross-section of dark matter. Detailed observations of several merging clusters have shown the intracluster gas to be displaced from the centroids of dark matter and galaxy density by ram pressure, while the latter components are spatially coincident, consistent with collisionless dark matter. This has been used to place upper limits on the dark matter particle self-interaction cross-section of order 1 cm{sup 2} g{sup -1}. The cluster A520 has been seen as a possible exception. We revisit A520 presenting new Hubble Space Telescope Advanced Camera for Surveys mosaic images and a Magellan image set. We perform a detailed weak-lensing analysis and show that the weak-lensing mass measurements and morphologies of the core galaxy-filled structures are mostly in good agreement with previous works. There is, however, one significant difference: We do not detect the previously claimed 'dark core' that contains excess mass with no significant galaxy overdensity at the location of the X-ray plasma. This peak has been suggested to be indicative of a large self-interaction cross-section for dark matter (at least {approx}5{sigma} larger than the upper limit of 0.7 cm{sup 2} g{sup -1} determined by observations of the Bullet Cluster). We find no such indication and instead find that the mass distribution of A520, after subtraction of the X-ray plasma mass, is in good agreement with the luminosity distribution of the cluster galaxies. We conclude that A520 shows no evidence to contradict the collisionless dark matter scenario.

Clowe, Douglas [Department of Physics and Astronomy, Ohio University, 251B Clippinger Labs, Athens, OH 45701 (United States); Markevitch, Maxim [NASA Goddard Space Flight Center, Code 662, 8800 Greenbelt Road, Greenbelt, MD 20706 (United States); Bradac, Marusa [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, Anthony H.; Chung, Sun Mi [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Massey, Richard [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Zaritsky, Dennis, E-mail: clowe@ohio.edu [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

2012-10-20T23:59:59.000Z

46

Weak Lensing Analysis of the z~0.8 cluster CL 0152-1357 with the Advanced Camera for Surveys  

E-Print Network (OSTI)

We present a weak lensing analysis of the X-ray luminous cluster CL 0152-1357 at z~0.84 using HST/ACS observations. The unparalleled resolution and sensitivity of ACS enable us to measure weakly distorted, faint background galaxies to the extent that the number density reaches ~175 arcmin^-2. The PSF of ACS has a complicated shape that also varies across the field. We construct a PSF model for ACS from an extensive investigation of 47 Tuc stars in a modestly crowded region. We show that this model PSF excellently describes the PSF variation pattern in the cluster observation when a slight adjustment of ellipticity is applied. The high number density of source galaxies and the accurate removal of the PSF effect through moment-based deconvolution allow us to restore the dark matter distribution of the cluster in great detail. The direct comparison of the mass map with the X-ray morphology from Chandra observations shows that the two peaks of intracluster medium traced by X-ray emission are lagging behind the corresponding dark matter clumps, indicative of an on-going merger. The overall mass profile of the cluster can be well described by an NFW profile with a scale radius of r_s =309+-45 kpc and a concentration parameter of c=3.7+-0.5. The mass estimates from the lensing analysis are consistent with those from X-ray and Sunyaev-Zeldovich analyses. The predicted velocity dispersion is also in good agreement with the spectroscopic measurement from VLT observations. In the adopted WMAP cosmology, the total projected mass and the mass-to-light ratio within 1 Mpc are estimated to be 4.92+-0.44 10^14 solar mass and 95+-8 solar mass/solar luminosity, respectively.

M. J. Jee; R. L. White; N. Benitez; H. C. Ford; J. P. Blakeslee; P. Rosati; R. Demarco; G. D. Illingworth

2004-09-13T23:59:59.000Z

47

A generalized lens equation for light deflection in weak gravitational fields  

E-Print Network (OSTI)

A generalized lens equation for weak gravitational fields in Schwarzschild metric and valid for finite distances of source and observer from the light deflecting body is suggested. The magnitude of neglected terms in the generalized lens equation is estimated to be smaller than or equal to 15 Pi/4 (m/d')^2, where m is the Schwarzschild radius of massive body and d' is Chandrasekhar's impact parameter. The main applications of this generalized lens equation are extreme astrometrical configurations, where 'Standard post-Newtonian approach' as well as 'Classical lens equation' cannot be applied. It is shown that in the appropriate limits the proposed lens equation yields the known post-Newtonian terms, 'enhanced' post-post-Newtonian terms and the Classical lens equation, thus provides a link between these both essential approaches for determining the light deflection.

Sven Zschocke

2011-05-18T23:59:59.000Z

48

JOINT ANALYSIS OF CLUSTER OBSERVATIONS. II. CHANDRA/XMM-NEWTON X-RAY AND WEAK LENSING SCALING RELATIONS FOR A SAMPLE OF 50 RICH CLUSTERS OF GALAXIES  

SciTech Connect

We present a study of multiwavelength X-ray and weak lensing scaling relations for a sample of 50 clusters of galaxies. Our analysis combines Chandra and XMM-Newton data using an energy-dependent cross-calibration. After considering a number of scaling relations, we find that gas mass is the most robust estimator of weak lensing mass, yielding 15% {+-} 6% intrinsic scatter at r{sub 500}{sup WL} (the pseudo-pressure Y{sub X} yields a consistent scatter of 22% {+-} 5%). The scatter does not change when measured within a fixed physical radius of 1 Mpc. Clusters with small brightest cluster galaxy (BCG) to X-ray peak offsets constitute a very regular population whose members have the same gas mass fractions and whose even smaller (<10%) deviations from regularity can be ascribed to line of sight geometrical effects alone. Cool-core clusters, while a somewhat different population, also show the same (<10%) scatter in the gas mass-lensing mass relation. There is a good correlation and a hint of bimodality in the plane defined by BCG offset and central entropy (or central cooling time). The pseudo-pressure Y{sub X} does not discriminate between the more relaxed and less relaxed populations, making it perhaps the more even-handed mass proxy for surveys. Overall, hydrostatic masses underestimate weak lensing masses by 10% on the average at r{sub 500}{sup WL}; but cool-core clusters are consistent with no bias, while non-cool-core clusters have a large and constant 15%-20% bias between r{sub 2500}{sup WL} and r{sub 500}{sup WL}, in agreement with N-body simulations incorporating unthermalized gas. For non-cool-core clusters, the bias correlates well with BCG ellipticity. We also examine centroid shift variance and power ratios to quantify substructure; these quantities do not correlate with residuals in the scaling relations. Individual clusters have for the most part forgotten the source of their departures from self-similarity.

Mahdavi, Andisheh [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94131 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Babul, Arif; Bildfell, Chris [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8W 3P6 (Canada); Jeltema, Tesla [Santa Cruz Institute for Particle Physics, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Henry, J. Patrick [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2013-04-20T23:59:59.000Z

49

Presence of Dark Energy and Dark Matter : Does Cosmic Acceleration signifies a Weak Gravitational collapse?  

E-Print Network (OSTI)

In this work the collapsing process of a spherically symmetric star, made of dust cloud, in the background of dark energy is studied for two different gravity theories separately, i.e., DGP Brane gravity and Loop Quantum gravity. Two types of dark energy fluids, namely, Modified Chaplygin gas and Generalised Cosmic Chaplygin gas are considered for each model. Graphs are drawn to characterize the nature and the probable outcome of gravitational collapse. A comparative study is done between the collapsing process in the two different gravity theories. It is found that in case of dark matter, there is a great possibility of collapse and consequent formation of Black hole. In case of dark energy possibility of collapse is far lesser compared to the other cases, due to the large negative pressure of dark energy component. There is an increase in mass of the cloud in case of dark matter collapse due to matter accumulation. The mass decreases considerably in case of dark energy due to dark energy accretion on the cloud. In case of collapse with a combination of dark energy and dark matter, it is found that in the absence of interaction there is a far better possibility of formation of black hole in DGP brane model compared to Loop quantum cosmology model.

Prabir Rudra; Ritabrata Biswas; Ujjal Debnath

2012-04-03T23:59:59.000Z

50

SDSS J0806+2006 and SDSS J1353+1138: Two New Gravitationally Lensed Quasars from the Sloan Digital Sky Survey  

E-Print Network (OSTI)

We report the discoveries of two, two-image gravitationally lensed quasars selected from the Sloan Digital Sky Survey: SDSS J0806+2006 at z_s=1.540 and SDSS J1353+1138 at z_s=1.629 with image separations of 1.40" and 1.41" respectively. Spectroscopic and optical/near-infrared imaging follow-up observations show that the quasar images have identical redshifts and possess extended objects between the images that are likely to be lens galaxies at z_l~0.6 in SDSS J0806+2006 and z_l~0.3 in SDSS J1353+1138. The field of SDSS J0806+2006 contains several nearby galaxies that may significantly perturb the system, and SDSS J1353+1138 has an extra component near its Einstein ring that is probably a foreground star. Simple mass models with reasonable parameters reproduce the quasar positions and fluxes of both systems.

Inada, N; Becker, R H; White, R L; Gregg, M D; Schechter, P L; Kawano, Y; Kochanek, C S; Richards, G T; Schneider, D P; Barentine, J C; Brewington, H J; Brinkmann, J; Harvanek, M; Kleinman, S J; Krzesínski, J; Long, D; Neilsen, E H; Nitta, A; Snedden, S A; York, D G; Inada, Naohisa; Oguri, Masamune; Becker, Robert H.; White, Richard L.; Gregg, Michael D.; Schechter, Paul L.; Kawano, Yozo; Kochanek, Christopher S.; Richards, Gordon T.; Schneider, Donald P.; Brewington, Howard J.; Harvanek, Michael; Krzesinski, Jurek; Long, Dan; Neilsen, Eric H.; Nitta, Atsuko; Snedden, Stephanie A.; York, Donald G.

2006-01-01T23:59:59.000Z

51

SDSS J0806+2006 and SDSS J1353+1138: Two New Gravitationally Lensed Quasars from the Sloan Digital Sky Survey  

E-Print Network (OSTI)

We report the discoveries of two, two-image gravitationally lensed quasars selected from the Sloan Digital Sky Survey: SDSS J0806+2006 at z_s=1.540 and SDSS J1353+1138 at z_s=1.629 with image separations of 1.40" and 1.41" respectively. Spectroscopic and optical/near-infrared imaging follow-up observations show that the quasar images have identical redshifts and possess extended objects between the images that are likely to be lens galaxies at z_l~0.6 in SDSS J0806+2006 and z_l~0.3 in SDSS J1353+1138. The field of SDSS J0806+2006 contains several nearby galaxies that may significantly perturb the system, and SDSS J1353+1138 has an extra component near its Einstein ring that is probably a foreground star. Simple mass models with reasonable parameters reproduce the quasar positions and fluxes of both systems.

Naohisa Inada; Masamune Oguri; Robert H. Becker; Richard L. White; Michael D. Gregg; Paul L. Schechter; Yozo Kawano; Christopher S. Kochanek; Gordon T. Richards; Donald P. Schneider; J. C. Barentine; Howard J. Brewington; J. Brinkmann; Michael Harvanek; S. J. Kleinman; Jurek Krzesinski; Dan Long; Eric H. Neilsen, Jr.; Atsuko Nitta; Stephanie A. Snedden; Donald G. York

2005-12-09T23:59:59.000Z

52

Sdss j0806+2006 and sdss j1353+1138: two new gravitationally lensed quasars from the sloan digital sky survey  

Science Conference Proceedings (OSTI)

We report the discoveries of two, two-image gravitationally lensed quasars selected from the Sloan Digital Sky Survey: SDSS J0806+2006 at z{sub s}=1.540 and SDSS J1353+1138 at z{sub s}=1.629 with image separations of 1.40'' and 1.41'' respectively. Spectroscopic and optical/near-infrared imaging follow-up observations show that the quasar images have identical redshifts and possess extended objects between the images that are likely to be lens galaxies at z{sub l} {approx} 0.6 in SDSS J0806+2006 and z{sub l} {approx} 0.3 in SDSS J1353+1138. The field of SDSS J0806+2006 contains several nearby galaxies that may significantly perturb the system, and SDSS J1353+1138 has an extra component near its Einstein ring that is probably a foreground star. Simple mass models with reasonable parameters reproduce the quasar positions and fluxes of both systems.

Inada, Naohisa; Oguri, Masamune; Becker, Robert H.; White, Richard L.; Gregg, Michael D.; Schechter, Paul L.; Kawano, Yozo; Kochanek, Christopher S.; Richards, Gordon T.; Schneider, Donald P.; Barentine, J.C.; Brewington, Howard J.; Brinkmann, J.; Harvanek, Michael; Kleinman, S.J.; Krzesinski, Jurek; Long, Dan; Neilsen, Eric H., Jr.; Nitta, Atsuko; Snedden, Stephanie A.; York, Donald G.; /Tokyo U., Inst. Astron. /Princeton U. Observ. /Tokyo U. /LLNL, Livermore /UC, Davis /Baltimore, Space Telescope Sci. /MIT, MKI /Nagoya U. /Ohio State U., Dept. Astron. /Johns Hopkins U. /Penn State U., Astron. Astrophys. /Apache Point Observ. /Mt. Suhora Observ., Cracow /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI

2005-12-01T23:59:59.000Z

53

Demagnified gravitational waves from cosmological double neutron stars and gravitational wave foreground cleaning around 1 Hz  

Science Conference Proceedings (OSTI)

Gravitational waves (GWs) from cosmological double neutron star binaries (NS+NS) can be significantly demagnified by the strong gravitational lensing effect, and the proposed future missions such as the Big Bang Observer or Deci-hertz Interferometer Gravitational Wave Observatory might miss some of the demagnified GW signals below a detection threshold. The undetectable binaries would form a GW foreground, which might hamper detection of a very weak primordial GW signal. We discuss the outlook of this potential problem, using a simple model based on the singular isothermal sphere lens profile. Fortunately, it is expected that, for a presumable merger rate of NS+NSs, the residual foreground would be below the detection limit {omega}{sub GW,lim}{approx}10{sup -16} realized with the Big Bang Observer/Deci-hertz Interferometer Gravitational Wave Observatory by correlation analysis.

Seto, Naoki [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2009-11-15T23:59:59.000Z

54

Galactic Bulge Pixel Lensing Events  

E-Print Network (OSTI)

Gould & DePoy proposed a pixel lensing survey towards the Galactic bulge using a small aperture ( ? 65 mm) camera with a large pixel size ( ? 10 ? ? ) detector and deliberately degraded optics achieving 30 ? ? point spread function (PSF). In this paper, we estimate the event rate of this pixel lensing survey expected under various detection criteria, which are characterized by the threshold signal-to-noise ratio, (S/N)th, and event duration, tdur,th, and investigate the characteristics of the detectable events. From this investigation, we find that the event rate varies significantly in the range ? 6 yr ?1 – 120 yr ?1 depending strongly on the imposed detection criteria, implying that to maximize event detections it will be essential to identify events by diligently inspecting light variations and to promptly conduct followup observations for the identified events. Compared to events detectable from classic lensing surveys, the events detectable from the pixel lensing survey will generally involve brighter source stars and have higher amplifications. For the pixel lensing events detectable under the criteria of (S/N)th = 10 and tdur,th = 6 hr, we find that the baseline brightness of source stars will be in average ? 2 mag brighter than those of classic lensing events and ? 90 % will have amplifications A ? 20 and ? 40 % will be extreme microlensing events (EMEs) with A ? 200. Therefore, followup observations of the pixel lensing events will provide high quality data, which enable one to precisely determine the lensing parameters and obtain extra-information about the lenses and source stars. Especially, high amplifications events with A ? 20 will be important targets for high-efficiency planet detections and one can uniquely determine the mass, distance, and transverse speed of individual lenses for EMEs. Subject headings: gravitational lensing

Cheongho Han

2001-01-01T23:59:59.000Z

55

What can be learned from the lensed cosmic microwave background B-mode polarization power spectrum?  

E-Print Network (OSTI)

The effect of weak gravitational lensing on the cosmic microwave background (CMB) temperature anisotropies and polarization will provide access to cosmological information that cannot be obtained from the primary anisotropies alone. We compare the information content of the lensed B-mode polarization power spectrum, properly accounting for the non-Gaussian correlations between the power on different scales, with that of the unlensed CMB fields and the lensing potential. The latter represent the products of an (idealised) optimal analysis that exploits the lens-induced non-Gaussianity to reconstruct the fields. Compressing the non-Gaussian lensed CMB into power spectra is wasteful and leaves a tight degeneracy between the equation of state of dark energy and neutrino mass that is much stronger than in the more optimal analysis. Despite this, a power spectrum analysis will be a useful first step in analysing future B-mode polarization data. For this reason, we also consider how to extract accurate parameter constraints from the lensed B-mode power spectrum. We show with simulations that for cosmic-variance-limited measurements of the lensed B-mode power, including the non-Gaussian correlations in existing likelihood approximations gives biased parameter results. We develop a more refined likelihood approximation that performs significantly better. This new approximation should also be of more general interest in the wider context of parameter estimation from Gaussian CMB data.

Sarah Smith; Anthony Challinor; Graca Rocha

2005-11-24T23:59:59.000Z

56

Lensing duct  

DOE Patents (OSTI)

A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding is described. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic. 3 figures.

Beach, R.J.; Benett, W.J.

1994-04-26T23:59:59.000Z

57

Symmetric lenses  

Science Conference Proceedings (OSTI)

Lenses--bidirectional transformations between pairs of connected structures--have been extensively studied and are beginning to find their way into industrial practice. However, some aspects of their foundations remain poorly understood. In particular, ... Keywords: algebra, category theory, lens, view-update

Martin Hofmann; Benjamin Pierce; Daniel Wagner

2011-01-01T23:59:59.000Z

58

An ASCA-ROSAT Study of the Distant, Lensing Cluster A2390  

E-Print Network (OSTI)

We present the results of a combined study of ASCA and ROSAT observations of the distant cluster Abell 2390.We determine the surface brightness profile and the gas density distribution of the cluster from the ROSAT PSPC and HRI data. A combined spatially resolved spectral analysis of the ASCA and ROSAT data show that the temperature distribution of the intracluster medium of A2390 is consistent with an isothermal temperature distribution in the range 9 to 12 keV except for the central region for which we find strong evidence of a multi-temperature structure. We determine the gravitational mass profile of the cluster and find a mass value of 2e15 solar masses for a radius 3 Mpc. A comparison of the projected mass profiles of the cluster shows an excellent agreement between the mass determined from X-ray data and the mass determined from the models for the gravitational arc and the weak lensing results.

H. Boehringer; Y. Tanaka; R. F. Mushotzky; Y. Ikebe; M. Hattori

1998-03-30T23:59:59.000Z

59

An ASCA-ROSAT Study of the Distant, Lensing Cluster A2390  

E-Print Network (OSTI)

We present the results of a combined study of ASCA and ROSAT observations of the distant cluster Abell 2390.We determine the surface brightness profile and the gas density distribution of the cluster from the ROSAT PSPC and HRI data. A combined spatially resolved spectral analysis of the ASCA and ROSAT data show that the temperature distribution of the intracluster medium of A2390 is consistent with an isothermal temperature distribution in the range 9 to 12 keV except for the central region for which we find strong evidence of a multi-temperature structure. We determine the gravitational mass profile of the cluster and find a mass value of 2e15 solar masses for a radius 3 Mpc. A comparison of the projected mass profiles of the cluster shows an excellent agreement between the mass determined from X-ray data and the mass determined from the models for the gravitational arc and the weak lensing results.

Böhringer, H; Mushotzky, R F; Ikebe, Y; Hattori, M

1998-01-01T23:59:59.000Z

60

Gravitation and Special Relativity  

E-Print Network (OSTI)

A mathematical derivation of Maxwell's equations for gravitation, based on a mathematical proof of Faraday's Law, is presented. The theory provides a linear, relativistic Lagrangian field theory of gravity in a weak field, and paves the way to a better understanding of the structure of the energy-momentum tensor in the Einstein Field Equations. Hence it is directly relevant to problems in modern cosmology. The derivation, independent of the perturbation theory of Einstein's equations, puts the gravitational and electromagnetic fields on an equal footing for weak fields, contrary to generally held views. The historical objections to a linear Lorentz invariant field theory of gravity are refuted for weak fields.

D. H. Sattinger

2013-05-20T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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61

Carbon nanotube zoom lenses  

Science Conference Proceedings (OSTI)

We show that convergent or divergent zoom lenses with focal length variations up to approximately 100% can be implemented by growing arrays of carbon nanotubes (CNTs) on curved templates. Unique lenses, which can change their character from divergent ...

D. Dragoman; M. Dragoman

2003-06-01T23:59:59.000Z

62

CLASS B2108+213: A new wide separation gravitational lens system  

E-Print Network (OSTI)

We present observations of CLASS B2108+213, the widest separation gravitational lens system discovered by the Cosmic Lens All-Sky Survey. Radio imaging using the VLA at 8.46 GHz and MERLIN at 5 GHz shows two compact components separated by 4.56 arcsec with a faint third component in between which we believe is emission from a lensing galaxy. 5-GHz VLBA observations reveal milliarcsecond-scale structure in the two lensed images that is consistent with gravitational lensing. Optical emission from the two lensed images and two lensing galaxies within the Einstein radius is detected in Hubble Space Telescope imaging. Furthermore, an optical gravitational arc, associated with the strongest lensed component, has been detected. Surrounding the system are a number of faint galaxies which may help explain the wide image separation. A plausible mass distribution model for CLASS B2108+213 is also presented.

J. P. McKean; I. W. A. Browne; N. J. Jackson; L. V. E. Koopmans; M. A. Norbury; T. Treu; T. D. York; A. D. Biggs; R. D. Blandford; A. G. de Bruyn; C. D. Fassnacht; S. Mao; S. T. Myers; T. J. Pearson; P. M. Phillips; A. C. S. Readhead; D. Rusin; P. N. Wilkinson

2004-10-22T23:59:59.000Z

63

(Lack of) lensing constraints on cluster dark matter profiles  

E-Print Network (OSTI)

Using stellar dynamics and strong gravitational lensing as complementary probes, Sand et al. (2002, 2003) have recently claimed strong evidence for shallow dark matter density profiles in several lensing clusters, which may conflict with predictions of the Cold Dark Matter paradigm. However, systematic uncertainties in the analysis weaken the constraints. By re-analyzing their data, we argue that the tight constraints claimed by Sand et al., were driven by prior assumptions. Relaxing the assumptions, we find that no strong constraints may be derived on the dark matter inner profile from the Sand et al. data; we find satisfactory fits (with reasonable parameters) for a wide range of inner slopes 0 < beta < 1.4. Useful constraints on the mass distributions of lensing clusters can still be obtained, but they require moving beyond mere measurements of lensing critical radii into the realm of detailed lens modeling.

Neal Dalal; Charles R. Keeton

2003-12-02T23:59:59.000Z

64

A VLBI Study of the Gravitational Lens JVAS B0218+357  

E-Print Network (OSTI)

We present the results of phase-referenced VLBA+Effelsberg observations at five frequencies of the gravitational lens B0218+357 to establish the precise registration of the A and B lensed image positions.

R. Mittal; R. Porcas; O. Wucknitz; A. Biggs

2004-12-30T23:59:59.000Z

65

Gravitational energy  

E-Print Network (OSTI)

Observers at rest in a stationary spacetime flat at infinity can measure small amounts of rest-mass+internal energies+kinetic energies+pressure energy in a small volume of fluid attached to a local inertial frame. The sum of these small amounts is the total "matter energy" for those observers. The total mass-energy minus the matter energy is the binding gravitational energy. Misner, Thorne and Wheeler evaluated the gravitational energy of a spherically symmetric static spacetime. Here we show how to calculate gravitational energy in any static and stationary spacetime for isolated sources with a set of observers at rest. The result of MTW is recovered and we find that electromagnetic and gravitational 3-covariant energy densities in conformastatic spacetimes are of opposite signs. Various examples suggest that gravitational energy is negative in spacetimes with special symmetries or when the energy-momentum tensor satisfies usual energy conditions.

Joseph Katz

2005-10-20T23:59:59.000Z

66

Gravitational waves from gravitational collapse  

Science Conference Proceedings (OSTI)

Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

Fryer, Christopher L [Los Alamos National Laboratory; New, Kimberly C [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

67

Enhanced lensing rate by clustering of massive galaxies: newly discovered systems in the SLACS fields  

E-Print Network (OSTI)

[Abridged] We exploit the clustering of massive galaxies to perform a high efficiency imaging search for gravitational lenses. Our dataset comprises 44 fields imaged by the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS), each of which is centered on a lens discovered by the Strong Lens ACS Survey (SLACS). We compare four different search methods: 1) automated detection with the HST Archive Galaxy-scale Gravitational Lens Survey (HAGGLeS) robot, 2) examining cutout images of bright galaxies (BGs) after subtraction of a smooth galaxy light distribution, 3) examining the unsubtracted BG cutouts, and 4) performing a full-frame visual inspection of the ACS images. We compute purity and completeness and consider investigator time for the four algorithms, using the main SLACS lenses as a testbed. The first and second algorithms perform the best. We present the four new lens systems discovered during this comprehensive search, as well as one other likely candidate. For each new lens we use the fundamental plane to estimate the lens velocity dispersion and predict, from the resulting lens geometry, the redshifts of the lensed sources. Two of these new systems are found in galaxy clusters, which include the SLACS lenses in the two respective fields. Overall we find that the enhanced lens abundance (30^{+24}_{-8} lenses/degree^2) is higher than expected for random fields (12^{+4}_{-2} lenses/degree^2 for the COSMOS survey). Additionally, we find that the gravitational lenses we detect are qualitatively different from those in the parent SLACS sample: this imaging survey is largely probing higher-redshift, and lower-mass, early-type galaxies.

Elisabeth R. Newton; Philip J. Marshall; Tommaso Treu

2008-10-21T23:59:59.000Z

68

Weak lensing flexion as a probe of galaxy cluster substructure  

E-Print Network (OSTI)

Measuring galaxy cluster total masses and the amount of dark matter substructure within galaxy cluster haloes is a fundamental probe of the ACDM model of structure formation, as well as the interactions between baryonic ...

Cain, Benjamin Martin

2011-01-01T23:59:59.000Z

69

Galactic Bulge Pixel Lensing Events  

E-Print Network (OSTI)

Gould & DePoy proposed a pixel lensing survey towards the Galactic bulge using a small aperture (~65 mm) camera with a large pixel size (10") detector and deliberately degraded optics achieving 30" PSF. In this paper, we estimate the event rate of this pixel lensing survey expected under various detection criteria, which are characterized by the threshold signal-to-noise ratio, (S/N)_{th}, and event duration, t_{dur,th}, and investigate the characteristics of the detectable events. From this investigation, we find that the event rate varies significantly in the range ~6/yr - 120/yr depending strongly on the imposed detection criteria, implying that to maximize event detections it will be essential to identify events by diligently inspecting light variations and to promptly conduct followup observations for the identified events. Compared to events detectable from classic lensing surveys, the events detectable from the pixel lensing survey will generally involve brighter source stars and have higher amplifications. For the pixel lensing events detectable under the criteria of (S/N)_{th}=10 and t_{dur,th}=6 hr, we find that the baseline brightness of source stars will be in average ~2 mag brighter than those of classic lensing events and ~90% will have amplifications A> 20 and ~40% will be extreme EMEs with A>200. Therefore, followup observations of the pixel lensing events will provide high quality data, which enable one to precisely determine the lensing parameters and obtain extra-information about the lenses and source stars. Especially, high amplifications events with A>20 will be important targets for high-efficiency planet detections and one can uniquely determine the mass, distance, and transverse speed of individual lenses for EMEs.

Cheongho Han

2001-03-28T23:59:59.000Z

70

Gravitational Helioseismology?  

E-Print Network (OSTI)

The magnitudes of the external gravitational perturbations associated with the normal modes of the Sun are evaluated to determine whether these solar oscillations could be observed with the proposed Laser Interferometer Space Antenna (LISA), a network of satellites designed to detect gravitational radiation. The modes of relevance to LISA---the $l=2$, low-order $p$, $f$ and $g$-modes---have not been conclusively observed to date. We find that the energy in these modes must be greater than about $10^{30} \\rm{ergs}$ in order to be observable above the LISA detector noise. These mode energies are larger than generally expected, but are much smaller than the current observational upper limits. LISA may be confusion-limited at the relevant frequencies due to the galactic background from short-period white dwarf binaries. Present estimates of the number of these binaries would require the solar modes to have energies above about $10^{33} \\rm{ergs}$ to be observable by LISA.

Curt Cutler; Lee Lindblom

1996-01-30T23:59:59.000Z

71

HUBBLE CONSTANT, LENSING, AND TIME DELAY IN RELATIVISTIC MODIFIED NEWTONIAN DYNAMICS  

SciTech Connect

The time delay in galaxy gravitational lensing systems has been used to determine the value of the Hubble constant. As with other dynamical phenomena on the galaxy scale, dark matter is often invoked in gravitational lensing to account for the 'missing mass' (the apparent discrepancy between the dynamical mass and the luminous mass). Alternatively, modified gravity can be used to explain the discrepancy. In this paper, we adopt the tensor-vector-scalar gravity (TeVe S), a relativistic version of Modified Newtonian Dynamics, to study gravitational lensing phenomena and derive the formulae needed to evaluate the Hubble constant. We test our method on quasar lensing by elliptical galaxies in the literature. We focus on double-image systems with time delay measurement. Three candidates are suitable for our study: HE 2149-2745, FBQ J0951+2635, and SBS 0909+532. The Hubble constant obtained is consistent with the value used to fit the cosmic microwave background result in a neutrino cosmological model.

Tian, Yong [Department of Physics, National Central University, Jhongli, Taiwan 320 (China); Ko, Chung-Ming [Institute of Astronomy, Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 320 (China); Chiu, Mu-Chen, E-mail: yonngtian@gmail.com, E-mail: cmko@astro.ncu.edu.tw, E-mail: mcc@roe.ac.uk [Scottish University Physics Alliance, Institute for Astronomy, the Royal Observatory, University of Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)

2013-06-20T23:59:59.000Z

72

Class B0631+519: Last of the Class Lenses  

SciTech Connect

We report the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the VLA, MERLIN and the VLBA reveals a doubly-imaged flat-spectrum radio core, a doubly-imaged steep-spectrum radio lobe and possible quadruply-imaged emission from a second lobe. The maximum separation between the lensed images is 1.16 arcsec. High resolution mapping with the VLBA at 5 GHz resolves the most magnified image of the radio core into a number of sub-components spread across approximately 20 mas. No emission from the lensing galaxy or an odd image is detected down to 0.31 mJy (5{sigma}) at 8.4 GHz. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as previously discovered by optical spectroscopy. We find that the foreground galaxy at z=0.0896 is a small irregular, and that the other, at z=0.6196 is a massive elliptical which appears to contribute the majority of the lensing effect. The host galaxy of the lensed source is detected in the HST near-infrared imaging as a set of arcs, which form a nearly complete Einstein ring. Mass modeling using non-parametric techniques can reproduce the near-infrared observations and indicates that the small irregular galaxy has a (localized) effect on the flux density distribution in the Einstein ring at the 5-10% level.

York, Tom; Jackson, N.; Browne, I.W.A.; Koopmans, L.V.E.; McKean, J.P.; Norbury, M.A.; Biggs, A.D.; Blandford, R.D.; de Bruyn, A.G.; Fassnacht, C.D.; Myers, S.T.; Pearson, T.J.; Phillips, P.M.; Readhead, A.C.S.; Rusin, D.; Wilkinson, P.N.; /Jodrell Bank /Kapteyn Astron. Inst., Groningen /UC, Davis /JIVE, Dwingeloo /KIPAC, Menlo Park /NFRA, Dwingeloo /NRAO, Socorro /Caltech /Pennsylvania U.

2005-05-31T23:59:59.000Z

73

Galactic Bulge Pixel Lensing Events  

E-Print Network (OSTI)

Gould & DePoy proposed a pixel lensing survey towards the Galactic bulge using a small aperture (~65 mm) camera with a large pixel size (10") detector and deliberately degraded optics achieving 30" PSF. In this paper, we estimate the event rate of this pixel lensing survey expected under various detection criteria, which are characterized by the threshold signal-to-noise ratio, (S/N)_{th}, and event duration, t_{dur,th}, and investigate the characteristics of the detectable events. From this investigation, we find that the event rate varies significantly in the range ~6/yr - 120/yr depending strongly on the imposed detection criteria, implying that to maximize event detections it will be essential to identify events by diligently inspecting light variations and to promptly conduct followup observations for the identified events. Compared to events detectable from classic lensing surveys, the events detectable from the pixel lensing survey will generally involve brighter source stars and have higher amplif...

Han, C

2001-01-01T23:59:59.000Z

74

CLASS B0631+519: Last of the CLASS lenses  

E-Print Network (OSTI)

We report the discovery of a new gravitational lens system from the CLASS survey, CLASS B0631+519. VLA, MERLIN and VLBA observations show a doubly-imaged radio core, a doubly-imaged lobe and a second lobe that is probably quadruply-imaged. The maximum image separation is 1.16 arcseconds. The VLBA resolves the most magnified image of the flat-spectrum radio core into a number of sub-components spread across approximately 20 milli-arcseconds. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as was previously discovered by optical spectroscopy. The nearer galaxy at z=0.0896 is a small blue irregular, while the more distant galaxy at z=0.6196 is an elliptical type and appears to contribute most of the lensing effect. The host galaxy of the lensed source is visible in NICMOS imaging as a set of arcs that form an almost complete Einstein ring. Mass modelling using non-parametric techniques can reproduce the ring and indicates that the irregular galaxy has a (localised) effect on the flux density distribution in the Einstein ring at the 5-10% level.

T. York; N. Jackson; I. W. A. Browne; L. V. E. Koopmans; J. P. McKean; M. A. Norbury; A. D. Biggs; R. D. Blandford; A. G. de Bruyn; C. D. Fassnacht; S. T. Myers; T. J. Pearson; P. M. Phillips; A. C. S. Readhead; D. Rusin; P. N. Wilkinson

2005-05-05T23:59:59.000Z

75

Galaxy density profiles and shapes -- I. simulation pipeline for lensing by realistic galaxy models  

E-Print Network (OSTI)

Studies of strong gravitational lensing in current and upcoming wide and deep photometric surveys, and of stellar kinematics from (integral-field) spectroscopy at increasing redshifts, promise to provide valuable constraints on galaxy density profiles and shapes. However, both methods are affected by various selection and modelling biases, whch we aim to investigate in a consistent way. In this first paper in a series we develop a flexible but efficient pipeline to simulate lensing by realistic galaxy models. These galaxy models have separate stellar and dark matter components, each with a range of density profiles and shapes representative of early-type, central galaxies without significant contributions from other nearby galaxies. We use Fourier methods to calculate the lensing properties of galaxies with arbitrary surface density distributions, and Monte Carlo methods to compute lensing statistics such as point-source lensing cross-sections. Incorporating a variety of magnification bias modes lets us examine different survey limitations in image resolution and flux. We rigorously test the numerical methods for systematic errors and sensitivity to basic assumptions. We also determine the minimum number of viewing angles that must be sampled in order to recover accurate orientation-averaged lensing quantities. We find that for a range of non-isothermal stellar and dark matter density profiles typical of elliptical galaxies, the combined density profile and corresponding lensing properties are surprisingly close to isothermal around the Einstein radius. The converse implication is that constraints from strong lensing and/or stellar kinematics, which are indeed consistent with isothermal models near the Einstein radius, cannot trivially be extrapolated to smaller and larger radii.

Glenn van de Ven; Rachel Mandelbaum; Charles R. Keeton

2008-08-19T23:59:59.000Z

76

Tachyons and Gravitational Cherenkov Radiation  

E-Print Network (OSTI)

AND GRAVITATIONAL CHERENKOV RADIATION CHARLES SCHWARTZwould emit gravitational radiation. It is very small.gravitational waves; Cherenkov radiation. In a recent work,

Schwartz, Charles

2011-01-01T23:59:59.000Z

77

A MICROLENSING MEASUREMENT OF DARK MATTER FRACTIONS IN THREE LENSING GALAXIES  

Science Conference Proceedings (OSTI)

Direct measurements of dark matter distributions in galaxies are currently only possible through the use of gravitational lensing observations. Combinations of lens modeling and stellar velocity dispersion measurements provide the best constraints on dark matter distributions in individual galaxies, however they can be quite complex. In this paper, we use observations and simulations of gravitational microlensing to measure the smooth (dark) matter mass fraction at the position of lensed images in three lens galaxies: MG 0414+0534, SDSS J0924+0219, and Q2237+0305. The first two systems consist of early-type lens galaxies, and both display a flux ratio anomaly in their close image pair. Anomalies such as these suggest that a high smooth matter percentage is likely, and indeed we prefer {approx}50% smooth matter in MG 0414+0534 and {approx}80% in SDSS J0924+0219 at the projected locations of the lensed images. Q2237+0305 differs somewhat in that its lensed images lie in the central kiloparsec of the barred spiral lens galaxy, where we expect stars to dominate the mass distribution. In this system, we find a smooth matter percentage that is consistent with zero.

Bate, N. F.; Webster, R. L.; Wyithe, J. S. B. [School of Physics, University of Melbourne, Parkville, Vic. 3010 (Australia); Floyd, D. J. E., E-mail: nbate@physics.unimelb.edu.au [OCIW, Las Campanas Observatory, Casilla 601, Colina El Pino, La Serena, Chile. (Chile)

2011-04-10T23:59:59.000Z

78

Intrinsic intraday variability in the gravitational lens system B0218+357  

E-Print Network (OSTI)

Radio monitoring of the gravitational lens system B0218+357 reveals it to be a highly variable source with variations on timescales of a few days correlated in both images. This shows that the variability is intrinsic to the background lensed source and suggests that similar variations in other intraday variable sources can also be intrinsic in origin.

A. D. Biggs; I. W. A. Browne; P. N. Wilkinson

2000-12-22T23:59:59.000Z

79

Matter density perturbations and effective gravitational constant in modified gravity models of dark energy  

E-Print Network (OSTI)

We derive the equation of matter density perturbations on sub-horizon scales for a general Lagrangian density f(R, phi, X) that is a function of a Ricci scalar R, a scalar field phi and a kinetic term X=-(nabla phi)^2/2. This is useful to constrain modified gravity dark energy models from observations of large-scale structure and weak lensing. We obtain the solutions for the matter perturbation delta_m as well as the gravitational potential Phi for some analytically solvable models. In a f(R) dark energy model with the Lagrangian density f(R)=alpha R^{1+m}-Lambda, the growth rates of perturbations exhibit notable differences from those in the standard Einstein gravity unless m is very close to 0. In scalar-tensor models with the Lagrangian density f=F(phi)R+2p(phi,X) we relate the models with coupled dark energy scenarios in the Einstein frame and reproduce the equations of perturbations known in the current literature by making a conformal transformation. We also estimate the evolution of perturbations in both Jordan and Einstein frames when the energy fraction of dark energy is constant during the matter-dominated epoch.

Shinji Tsujikawa

2007-05-08T23:59:59.000Z

80

Watching Gravitational Waves  

E-Print Network (OSTI)

In the vicinity of merging neutron strar binaries or supernova remnants, gravitational waves can interact with the prevailing strong magnetic fields. The resulting partial conversion of gravitational waves into electromagnetic (radio) waves might prove to be an indirect way of detecting gravitational waves from such sources. Another interesting interaction considered in this article is the excitation of magnetosonic plasma waves by a gravitational wave passing through the surrounding plasma. The transfer of gravitational wave energy into the plasma might help to fuel the `fireball' of electromagnetic radiation observed in gamma ray bursts. In the last section of the article, a dispersion relation is derived for such magnetosonic plasma waves driven by a gravitational wave.

Joachim Moortgat

2001-04-02T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Quantal Definition of the Weak Equivalence Principle  

E-Print Network (OSTI)

The present work analyzes the meaning of the Weak Equivalence Principle in the context of quantum mechanics. A quantal definition for this principle is introduced. This definition does not require the concept of trajectory and relies upon the phase shift induced by a gravitational field in the context of a quantum interference experiment of two coherent beams of particles. In other words, it resorts to wave properties of the system and not to classical concepts as the idea of trajectory.

Abel Camacho; Arturo Camacho-Guardian

2008-11-03T23:59:59.000Z

82

Multibaseline gravitational wave radiometry  

E-Print Network (OSTI)

We present a statistic for the detection of stochastic gravitational wave backgrounds (SGWBs) using radiometry with a network of multiple baselines. We also quantitatively compare the sensitivities of existing baselines and their network to SGWBs. We assess how the measurement accuracy of signal parameters, e.g., the sky position of a localized source, can improve when using a network of baselines, as compared to any of the single participating baselines. The search statistic itself is derived from the likelihood ratio of the cross correlation of the data across all possible baselines in a detector network and is optimal in Gaussian noise. Specifically, it is the likelihood ratio maximized over the strength of the SGWB, and is called the maximized-likelihood ratio (MLR). One of the main advantages of using the MLR over past search strategies for inferring the presence or absence of a signal is that the former does not require the deconvolution of the cross correlation statistic. Therefore, it does not suffer from errors inherent to the deconvolution procedure and is especially useful for detecting weak sources. In the limit of a single baseline, it reduces to the detection statistic studied by Ballmer [Class. Quant. Grav. 23, S179 (2006)] and Mitra et al. [Phys. Rev. D 77, 042002 (2008)]. Unlike past studies, here the MLR statistic enables us to compare quantitatively the performances of a variety of baselines searching for a SGWB signal in (simulated) data. Although we use simulated noise and SGWB signals for making these comparisons, our method can be straightforwardly applied on real data.

Dipongkar Talukder; Sanjit Mitra; Sukanta Bose

2010-12-21T23:59:59.000Z

83

Gravitational radiation from primordial helical inverse cascade magnetohydrodynamic turbulence  

SciTech Connect

We consider the generation of gravitational waves by primordial helical inverse-cascade magnetohydrodynamic (MHD) turbulence produced by bubble collisions at the electroweak phase transition. We extend the previous study 1 by considering both currently discussed models of MHD turbulence. For popular electroweak phase transition parameter values, the generated gravitational wave spectrum is only weakly dependent on the MHD turbulence model. Compared with the unmagnetized electroweak phase transition case, the spectrum of MHD-turbulence-generated gravitational waves peaks at lower frequency with larger amplitude and can be detected by the proposed Laser Interferometer Space Antenna.

Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Astrophysical Observatory, Ilia Chavchavadze State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Campanelli, Leonardo [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); INFN - Sezione di Bari, I-70126 Bari (Italy); Gogoberidze, Grigol [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); National Astrophysical Observatory, Ilia Chavchavadze State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Maravin, Yurii; Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

2008-12-15T23:59:59.000Z

84

Large Lenses of Highly Saline Mediterranean Water  

Science Conference Proceedings (OSTI)

Isolated compact anticyclonic eddies or salt lenses were found in the Canary Basin. Hydrographic surveys of three such lenses show large anomalies of salinity and temperature (0.8, 2.5°C). They are centered at 1100 m, have a vertical extent of ...

Laurence Armi; Walter Zenk

1984-10-01T23:59:59.000Z

85

Gravitational-wave confusion background from cosmological compact binaries: Implications for future terrestrial detectors  

E-Print Network (OSTI)

Increasing the sensitivity of a gravitational-wave (GW) detector improves our ability to measure the characteristics of detected sources. It also increases the number of weak signals that contribute to the data. Because ...

Regimbau, T.

86

On the gravitational redshift  

E-Print Network (OSTI)

The study of the gravitational redshift -- a relative wavelength increase of $\\approx 2 \\times 10^{-6}$ was predicted for solar radiation by Einstein in 1908 -- is still an important subject in modern physics. In a dispute whether or not atom interferometry experiments can be employed for gravitational redshift measurements, two research teams have recently disagreed on the physical cause of the shift. Regardless of any discussion on the interferometer aspect -- we find that both groups of authors miss the important point that the ratio of gravitational to the electrostatic forces is generally very small. For instance, the gravitational force acting on an electron in a hydrogen atom situated in the Sun's photosphere to the electrostatic force between the proton and the electron is approximately $3 \\times 10^{-21}$. A comparison of this ratio with the predicted and observed solar redshift indicates a discrepancy of many orders of magnitude. Here we show, with Einstein's early assumption of the frequency of spectral lines depending only on the generating ion itself as starting point, that a solution can be formulated based on a two-step process in analogy with Fermi's treatment of the Doppler effect. It provides a sequence of physical processes in line with the conservation of energy and momentum resulting in the observed shift and does not employ a geometric description. The gravitational field affects the release of the photon and not the atomic transition. The control parameter is the speed of light. The atomic emission is then contrasted with the gravitational redshift of matter-antimatter annihilation events.

Klaus Wilhelm; Bhola N. Dwivedi

2013-07-01T23:59:59.000Z

87

Expanding impulsive gravitational waves  

E-Print Network (OSTI)

We explicitly demonstrate that the known solutions for expanding impulsive spherical gravitational waves that have been obtained by a "cut and paste" method may be considered to be impulsive limits of the Robinson-Trautman vacuum type N solutions. We extend these results to all the generically distinct subclasses of these solutions in Minkowski, de Sitter and anti-de Sitter backgrounds. For these we express the solutions in terms of a continuous metric. Finally, we also extend the class of spherical shock gravitational waves to include a non-zero cosmological constant.

J. Podolsky; J. B. Griffiths

1999-07-06T23:59:59.000Z

88

The Universe Adventure - Gravitational Equation  

NLE Websites -- All DOE Office Websites (Extended Search)

Gravitation Gravity and Mass Mass v. Force From the graph we can see that as the mass of the alien increases, the gravitational force (the alien's weight) also increases: mass...

89

Handbook for the GREAT08 Challenge: An image analysis competition for cosmological lensing  

E-Print Network (OSTI)

The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance for future observations in cosmology. The shapes of distant galaxies can be used to determine the properties of dark energy and the nature of gravity, because light from those galaxies is bent by gravity from the intervening dark matter. The observed galaxy images appear distorted, although only slightly, and their shapes must be precisely disentangled from the effects of pixelisation, convolution and noise. The worldwide gravitational lensing community has made significant progress in techniques to measure these distortions via the Shear TEsting Program (STEP). Via STEP, we have run challenges within our own community, and come to recognise that this particular image analysis problem is ideally matched to experts in statistical inference, inverse problems and computational learning. Thus, in order to continue the progress seen in recent years, we are seeking an infusion of new ideas from these communities. This document details the GREAT08 Challenge for potential participants. Please visit http://www.great08challenge.info for the latest information.

Sarah Bridle; John Shawe-Taylor; Adam Amara; Douglas Applegate; Sreekumar T. Balan; Joel Berge; Gary Bernstein; Hakon Dahle; Thomas Erben; Mandeep Gill; Alan Heavens; Catherine Heymans; F. William High; Henk Hoekstra; Mike Jarvis; Donnacha Kirk; Thomas Kitching; Jean-Paul Kneib; Konrad Kuijken; David Lagatutta; Rachel Mandelbaum; Richard Massey; Yannick Mellier; Baback Moghaddam; Yassir Moudden; Reiko Nakajima; Stephane Paulin-Henriksson; Sandrine Pires; Anais Rassat; Alexandre Refregier; Jason Rhodes; Tim Schrabback; Elisabetta Semboloni; Marina Shmakova; Ludovic van Waerbeke; Dugan Witherick; Lisa Voigt; David Wittman

2008-02-11T23:59:59.000Z

90

Cluster cross sections for strong lensing: analytic and numerical lens models  

E-Print Network (OSTI)

The statistics of gravitationally lensed arcs was recognised earlier as a potentially powerful cosmological probe. However, while fully numerical models find orders of magnitude difference between the arc probabilities in different cosmological models, analytic models tend to find markedly different results. We introduce in this paper an analytic cluster lens model which improves upon existing analytic models in four ways. (1) We use the more realistic Navarro-Frenk-White profile instead of singular isothermal spheres, (2) we include the effect of cosmology on the compactness of the lenses, (3) we use elliptical instead of axially symmetric lenses, and (4) we take the intrinsic ellipticity of sources into account. While these improvements to the analytic model lead to a pronounced increase of the arc probability, comparisons with numerical models of the same virial mass demonstrate that the analytic models still fall short by a substantial margin of reproducing the results obtained with numerical models. Using multipole expansions of cluster mass distributions, we show that the remaining discrepancy can be attributed to substructure inside clusters and tidal fields contributed by the cluster surroundings, effects that cannot reasonably and reliably be mimicked in analytic models.

Massimo Meneghetti; Matthias Bartelmann; Lauro Moscardini

2002-01-30T23:59:59.000Z

91

Testing general scalar-tensor gravity and massive gravity with cluster lensing  

E-Print Network (OSTI)

We explore the possibility of testing modified gravity exhibiting the Vainshtein mechanism against observations of cluster lensing. We work in the most general scalar-tensor theory with second-order field equations (Horndeski's theory), and derive static and spherically symmetric solutions, for which the scalar field is screened below a certain radius. It is found that the essential structure of the problem in the most general case can be captured by the program of classifying Vainshtein solutions out of different solutions to a quintic equation, as has been performed in the context of massive gravity. The key effect on gravitational lensing is that the second derivative of the scalar field can substantially be large at the transition from screened to unscreened regions, leaving a dip in the convergence. This allows us to put observational constraints on parameters characterizing the general scalar-tensor modification of gravity. We demonstrate how this occurs in massive gravity as an example, and discuss its observational signatures in cluster lensing.

Tatsuya Narikawa; Tsutomu Kobayashi; Daisuke Yamauchi; Ryo Saito

2013-02-10T23:59:59.000Z

92

Gravitational waves and fundamental physics  

E-Print Network (OSTI)

I give an overview of the motivations for gravitational-wave research, concentrating on the aspects related to ``fundamental'' physics.

Michele Maggiore

2006-02-15T23:59:59.000Z

93

Gravitational Wave Sources: An Overview  

Science Conference Proceedings (OSTI)

With full?sensitivity operation of the first generation of gravitational wave detectors now just around the corner

Bernard F. Schutz

2003-01-01T23:59:59.000Z

94

Toward gravitational wave detection  

E-Print Network (OSTI)

An overview of some tools and techniques being developed for data conditioning (regression of instrumental and environmental artifacts from the data channel), detector design evaluation (modeling the science ``reach'' of alternative detector designs and configurations), noise simulations for mock data challenges and analysis system validation, and analyses for the detection of gravitational radiation from gamma-ray burst sources.

L. S. Finn; G. Gonzalez; J. Hough; M. F. Huq; S. Mohanty; J. Romano; S. Rowan; P. R. Saulson; K. A. Strain

1999-11-02T23:59:59.000Z

95

Preprint typeset using L ATEX style emulateapj v. 10/09/06 ENHANCED LENSING RATE BY CLUSTERING OF MASSIVE GALAXIES: NEWLY DISCOVERED SYSTEMS IN THE SLACS FIELDS  

E-Print Network (OSTI)

Galaxy-scale strong gravitational lens systems are useful for a variety of astrophysical applications. However, their use is limited by the relatively small samples of lenses known to date. It is thus important to develop efficient ways to discover new systems both in present and forthcoming datasets. For future large high-resolution imaging surveys we anticipate an ever-growing need for efficiency and for independence from spectroscopic data. In this paper, we exploit the clustering of massive galaxies to perform a high efficiency imaging search for gravitational lenses. Our dataset comprises 44 fields imaged by the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS), each of which is centered on a lens discovered by the Strong Lens ACS Survey (SLACS). We compare four different search methods: 1) automated detection with the HST Archive Galaxy-scale Gravitational Lens Survey (HAGGLeS) robot, 2) examining cutout images of bright galaxies (BGs) after subtraction of a smooth galaxy light distribution, 3) examining the unsubtracted BG cutouts, and 4) performing a full-frame visual inspection of the ACS images. We compute purity and completeness and consider investigator time for the four algorithms, using the main SLACS lenses as a testbed. The first and second algorithms perform the best. We present the four new lens systems discovered during this

Elisabeth R. Newton; Philip J. Marshall; Tommaso Treu

2008-01-01T23:59:59.000Z

96

Gravitation as Anholonomy  

E-Print Network (OSTI)

A gravitational field can be seen as the anholonomy of the tetrad fields. This is more explicit in the teleparallel approach, in which the gravitational field-strength is the torsion of the ensuing Weitzenboeck connection. In a tetrad frame, that torsion is just the anholonomy of that frame. The infinitely many tetrad fields taking the Lorentz metric into a given Riemannian metric differ by point-dependent Lorentz transformations. Inertial frames constitute a smaller infinity of them, differing by fixed-point Lorentz transformations. Holonomic tetrads take the Lorentz metric into itself, and correspond to Minkowski flat spacetime. An accelerated frame is necessarily anholonomic and sees the electromagnetic field strength with an additional term.

R. Aldrovandi; P. B. Barros; J. G. Pereira

2003-01-21T23:59:59.000Z

97

Gravitational-Wave Detection using Multivariate Analysis  

E-Print Network (OSTI)

Searches for gravitational-wave bursts (transient signals, typically of unknown waveform) require identification of weak signals in background detector noise. The sensitivity of such searches is often critically limited by non-Gaussian noise fluctuations which are difficult to distinguish from real signals, posing a key problem for transient gravitational-wave astronomy. Current noise rejection tests are based on the analysis of a relatively small number of measured properties of the candidate signal, typically correlations between detectors. Multivariate analysis (MVA) techniques probe the full space of measured properties of events in an attempt to maximise the power to accurately classify events as signal or background. This is done by taking samples of known background events and (simulated) signal events to train the MVA classifier, which can then be applied to classify events of unknown type. We apply the boosted decision tree (BDT) MVA technique to the problem of detecting gravitational-wave bursts associated with gamma-ray bursts. We find that BDTs are able to increase the sensitive distance reach of the search by as much as 50%, corresponding to a factor of ~3 increase in sensitive volume. This improvement is robust against trigger sky position, large sky localisation error, poor data quality, and the simulated signal waveforms that are used. Critically, we find that the BDT analysis is able to detect signals that have different morphologies to those used in the classifier training and that this improvement extends to false alarm probabilities beyond the 3{\\sigma} significance level. These findings indicate that MVA techniques may be used for the robust detection of gravitational-wave bursts with a priori unknown waveform.

Thomas S. Adams; Duncan Meacher; James Clark; Patrick J. Sutton; Gareth Jones; Ariana Minot

2013-05-24T23:59:59.000Z

98

Tachyons and Gravitational Cherenkov Radiation  

E-Print Network (OSTI)

We calculate the rate at which a free tachyon (faster than light particle) would emit gravitational radiation. It is very small.

Schwartz, Charles

2011-01-01T23:59:59.000Z

99

Spherically Symmetric Gravitational Collapse  

E-Print Network (OSTI)

In this paper, we discuss gravitational collapse of spherically symmetric spacetimes. We derive a general formalism by taking two arbitrary spherically symmetric spacetimes with $g_{00}=1$. Israel's junction conditions are used to develop this formalism. The formulae for extrinsic curvature tensor are obtained. The general form of the surface energy-momentum tensor depending on extrinsic curvature tensor components is derived. This leads us to the surface energy density and the tangential pressure. The formalism is applied to two known spherically symmetric spacetimes. The results obtained show the regions for the collapse and expansion of the shell.

M. Sharif; Khadija Iqbal

2008-12-03T23:59:59.000Z

100

Constraints on primordial density perturbations from induced gravitational waves  

SciTech Connect

We consider the stochastic background of gravitational waves produced during the radiation-dominated hot big bang as a constraint on the primordial density perturbation on comoving length scales much smaller than those directly probed by the cosmic microwave background or large-scale structure. We place weak upper bounds on the primordial density perturbation from current data. Future detectors such as BBO and DECIGO will place much stronger constraints on the primordial density perturbation on small scales.

Assadullahi, Hooshyar; Wands, David [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom)

2010-01-15T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Gravitational Waves II: Emitting Systems  

E-Print Network (OSTI)

We use the basic equations that predict the emission of gravitational waves according to the Einstein gravitation theory to calculate the luminosities and the amplitudes of the waves generated by binary stars, pulsations of neutron stars, wobbling of deformed neutron stars, oscillating quadrupoles, rotating bars and collapsing and bouncing cores of supernovas. This paper was written to graduate and postgraduate students of Physics.

M. Cattani

2010-03-10T23:59:59.000Z

102

Automation Enhancement of Multilayer Laue Lenses  

SciTech Connect

X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

Lauer K. R.; Conley R.

2010-12-01T23:59:59.000Z

103

GRAVITATIONAL LENS MODELING WITH GENETIC ALGORITHMS AND PARTICLE SWARM OPTIMIZERS  

Science Conference Proceedings (OSTI)

Strong gravitational lensing of an extended object is described by a mapping from source to image coordinates that is nonlinear and cannot generally be inverted analytically. Determining the structure of the source intensity distribution also requires a description of the blurring effect due to a point-spread function. This initial study uses an iterative gravitational lens modeling scheme based on the semilinear method to determine the linear parameters (source intensity profile) of a strongly lensed system. Our 'matrix-free' approach avoids construction of the lens and blurring operators while retaining the least-squares formulation of the problem. The parameters of an analytical lens model are found through nonlinear optimization by an advanced genetic algorithm (GA) and particle swarm optimizer (PSO). These global optimization routines are designed to explore the parameter space thoroughly, mapping model degeneracies in detail. We develop a novel method that determines the L-curve for each solution automatically, which represents the trade-off between the image {chi}{sup 2} and regularization effects, and allows an estimate of the optimally regularized solution for each lens parameter set. In the final step of the optimization procedure, the lens model with the lowest {chi}{sup 2} is used while the global optimizer solves for the source intensity distribution directly. This allows us to accurately determine the number of degrees of freedom in the problem to facilitate comparison between lens models and enforce positivity on the source profile. In practice, we find that the GA conducts a more thorough search of the parameter space than the PSO.

Rogers, Adam; Fiege, Jason D. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T-2N2 (Canada)

2011-02-01T23:59:59.000Z

104

A New Quadruple Gravitational Lens System: CLASS B0128+437  

E-Print Network (OSTI)

High resolution MERLIN observations of a newly-discovered four-image gravitational lens system, B0128+437, are presented. The system was found after a careful re-analysis of the entire CLASS dataset. The MERLIN observations resolve four components in a characteristic quadruple-image configuration; the maximum image separation is 542 mas and the total flux density is 48 mJy at 5 GHz. A best-fit lens model with a singular isothermal ellipsoid results in large errors in the image positions. A significantly improved fit is obtained after the addition of a shear component, suggesting that the lensing system is more complex and may consist of multiple deflectors. The integrated radio spectrum of the background source indicates that it is a GigaHertz-Peaked Spectrum (GPS) source. It may therefore be possible to resolve structure within the radio images with deep VLBI observations and thus better constrain the lensing mass distribution.

P. M. Phillips; M. A. Norbury; L. V. E. Koopmans; I. W. A. Browne; N. J. Jackson; P. N. Wilkinson; A. D. Biggs; R. D. Blandford; A. G. de Bruyn; C. D. Fassnacht; P. Helbig; S. Mao; D. R. Marlow; S. T. Myers; T. J. Pearson; A. C. S. Readhead; D. Rusin; E. Xanthopoulos

2000-09-20T23:59:59.000Z

105

High resolution observations and mass modelling of the CLASS gravitational lens B1152+199  

E-Print Network (OSTI)

We present a series of high resolution radio and optical observations of the CLASS gravitational lens system B1152+199 obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN), Very Long Baseline Array (VLBA) and Hubble Space Telescope (HST). Based on the milliarcsecond-scale substructure of the lensed radio components and precise optical astrometry for the lensing galaxy, we construct models for the system and place constraints on the galaxy mass profile. For a single galaxy model with surface mass density Sigma(r) propto r^-beta, we find that 0.95 < beta < 1.21 at 2-sigma confidence. Including a second deflector to represent a possible satellite galaxy of the primary lens leads to slightly steeper mass profiles.

D. Rusin; M. Norbury; A. D. Biggs; D. R. Marlow; N. J. Jackson; I. W. A. Browne; P. N. Wilkinson; S. T. Myers

2001-10-04T23:59:59.000Z

106

Mass profiles of clusters of galaxies : a comparison of X-ray and weak lensing observations  

E-Print Network (OSTI)

Clusters of galaxies are useful probes of cosmology because they are the most massive bound systems and fair representatives of the matter composition of the universe. For clusters to be used as tracers of cosmic evolution, ...

Peng, En-Hsin

2011-01-01T23:59:59.000Z

107

A RECIPE TO PROBE ALTERNATIVE THEORIES OF GRAVITATION VIA N-BODY NUMERICAL SIMULATIONS. I. SPIRAL GALAXIES  

SciTech Connect

A way to probe alternative theories of gravitation is to study if they could account for the structures of the universe. We therefore modified the well-known Gadget-2 code to probe alternative theories of gravitation through galactic dynamics. As an application, we simulate the evolution of spiral galaxies to probe alternative theories of gravitation whose weak field limits have a Yukawa-like gravitational potential. These simulations show that galactic dynamics can be used to constrain the parameters associated with alternative theories of gravitation. It is worth stressing that the recipe given in this study can be applied to any other alternative theory of gravitation in which the superposition principle is valid.

Brandao, C. S. S.; De Araujo, J. C. N., E-mail: claudiosoriano.uesc@gmail.com, E-mail: jcarlos.dearaujo@inpe.br [Divisao de Astrofisica, Instituto Nacional de Pesquisas Espaciais, S. J. Campos, SP 12227-010 (Brazil)

2012-05-01T23:59:59.000Z

108

Inevitability of gravitational collapse  

SciTech Connect

It is proven that a sufficient accumulation of cold, uncharged, nonrotating matter cannot be stable against gravitational collapse. The highlights of the proof are: (1) fewer assumptions are made than previous arguments for collapse, in particular, the plausible, but unproved, causality'' assumption. (2) The amount of matter is measured by its baryon number, not its mass, since mass can be radiated away. (3) The precise analog of the argument that the Schwarzschild radius is proportional to the radius cubed does not suffice as a proof of the theorem for a very simple reason. As a result, it may be that an incompressible fluid is not the most resistant to collapse. (4) A crucial step in the proof appears to result from the details of the equations, and obvious physical insight into this mechanism is not provided. (auth)

Henyey, F.S.

1974-04-30T23:59:59.000Z

109

The gravitational energy-momentum tensor and the gravitational pressure  

E-Print Network (OSTI)

In the framework of the teleparallel equivalent of general relativity it is possible to establish the energy-momentum tensor of the gravitational field. This tensor has the following essential features: (1) it is identified directly in Einstein's field equations; (2) it is conserved and traceless; (3) it yields expressions for the energy and momentum of the gravitational field; (4)it is free of second (and highest) derivatives of the field variables; (5) the gravitational and matter energy-momentum tensors take place in the field equations on the same footing; (6) it is unique. However, it is not symmetric. We show that the spatial components of this tensor yield a consistent definition of the gravitational pressure.

J. W. Maluf

2005-04-18T23:59:59.000Z

110

Non-gravitational exceptional supermultiplets  

E-Print Network (OSTI)

We examine non-gravitational minimal supermultiplets which are based on the tensor gauge fields appearing as matter fields in exceptional generalised geometry. When possible, off-shell multiplets are given. The fields in the multiplets describe non-gravitational parts of the internal dynamics of compactifications of M-theory. In flat backgrounds, they enjoy a global U-duality symmetry, but also provide multiplets with a possibility of coupling to a generalised exceptional geometry.

Martin Cederwall

2013-02-27T23:59:59.000Z

111

STRONG GRAVITATIONAL LENS MODELING WITH SPATIALLY VARIANT POINT-SPREAD FUNCTIONS  

Science Conference Proceedings (OSTI)

Astronomical instruments generally possess spatially variant point-spread functions, which determine the amount by which an image pixel is blurred as a function of position. Several techniques have been devised to handle this variability in the context of the standard image deconvolution problem. We have developed an iterative gravitational lens modeling code called Mirage that determines the parameters of pixelated source intensity distributions for a given lens model. We are able to include the effects of spatially variant point-spread functions using the iterative procedures in this lensing code. In this paper, we discuss the methods to include spatially variant blurring effects and test the results of the algorithm in the context of gravitational lens modeling problems.

Rogers, Adam; Fiege, Jason D. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, R3T-2N2 (Canada)

2011-12-10T23:59:59.000Z

112

B0850+054: a new gravitational lens system from CLASS  

E-Print Network (OSTI)

We report the discovery of a new gravitational lens system from the CLASS survey. Radio observations with the VLA, the WSRT and MERLIN show that the radio source B0850+054 is comprised of two compact components with identical spectra, a separation of 0.7 arcsec and a flux density ratio of 6:1. VLBA observations at 5 GHz reveal structures that are consistent with the gravitational lens hypothesis. The brighter of the two images is resolved into a linear string of at least six sub-components whilst the weaker image is radially stretched towards the lens galaxy. UKIRT K-band imaging detects an 18.7 mag extended object, but the resolution of the observations is not sufficient to resolve the lensed images and the lens galaxy. Mass modelling has not been possible with the present data and the acquisition of high-resolution optical data is a priority for this system.

A. D. Biggs; D. Rusin; I. W. A. Browne; A. G. de Bruyn; N. J. Jackson; L. V. E. Koopmans; J. P. McKean; S. T. Myers; R. D. Blandford; K. -H. Chae; C. D. Fassnacht; M. A. Norbury; T. J. Pearson; P. M. Phillips; A. C. S. Readhead

2002-10-23T23:59:59.000Z

113

Shearfree cylindrical gravitational collapse  

Science Conference Proceedings (OSTI)

We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O. [Escuela de Fisica, Facultad de Ciencias, Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of); School of Mathematical Sciences, Queen Mary University of London, London E1 4NS (United Kingdom); School of Mathematical Sciences, Queen Mary University of London, London E1 4NS (United Kingdom); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil)

2009-09-15T23:59:59.000Z

114

Steven Weinberg, Weak Interactions, and Electromagnetic Interactions  

NLE Websites -- All DOE Office Websites (Extended Search)

Steven Weinberg and Steven Weinberg and Weak and Electromagnetic Interactions Resources with Additional Information Steven Weinberg Courtesy Dr. Steven Weinberg Steven "Weinberg is a professor of physics and astronomy at UT [The University of Texas] Austin and is founding director of the Theory Group in the College of Natural Sciences. [He is] well known for his development of a field theory that unifies the electromagnetic and weak nuclear forces, and for other major contributions to physics and cosmology ... Weinberg's work has been honored with numerous prizes, including the Nobel Prize in Physics in 1979 and the National Medal of Science in 1991. Weinberg is the author of the prize-winning book The First Three Minutes: A Modern View of the Origin of the Universe (which has been translated into 22 foreign languages) as well as Gravitation and Cosmology, The Discovery of Subatomic Particles, Dreams of a Final Theory and The Quantum Theory of Fields. ... Weinberg was the recipient of the Scientist as Poet prize from Rockefeller University for "extraordinary achievements in conveying - with passionate clarity - the ideas, history, explanatory power and aesthetic dimensions of fundamental physics." The citation mentioned two of Weinberg's books.

115

Compound Refractive Lenses for Thermal Neutron Applications  

SciTech Connect

This project designed and built compound refractive lenses (CRLs) that are able to focus, collimate and image using thermal neutrons. Neutrons are difficult to manipulate compared to visible light or even x rays; however, CRLs can provide a powerful tool for focusing, collimating and imaging neutrons. Previous neutron CRLs were limited to long focal lengths, small fields of view and poor resolution due to the materials available and manufacturing techniques. By demonstrating a fabrication method that can produce accurate, small features, we have already dramatically improved the focal length of thermal neutron CRLs, and the manufacture of Fresnel lens CRLs that greatly increases the collection area, and thus efficiency, of neutron CRLs. Unlike a single lens, a compound lens is a row of N lenslets that combine to produce an N-fold increase in the refraction of neutrons. While CRLs can be made from a variety of materials, we have chosen to mold Teflon lenses. Teflon has excellent neutron refraction, yet can be molded into nearly arbitrary shapes. We designed, fabricated and tested Teflon CRLs for neutrons. We demonstrated imaging at wavelengths as short as 1.26 ? with large fields of view and achieved resolution finer than 250 ?m which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.

Gary, Charles K.

2013-11-12T23:59:59.000Z

116

Are vortices in rotating superfluids breaking the Weak Equivalence Principle?  

E-Print Network (OSTI)

Due to the breaking of gauge symmetry in rotating superfluid Helium, the inertial mass of a vortex diverges with the vortex size. The vortex inertial mass is thus much higher than the classical inertial mass of the vortex core. An equal increase of the vortex gravitational mass is questioned. The possibility that the vortices in a rotating superfluid could break the weak equivalence principle in relation with a variable speed of light in the superfluid vacuum is debated. Experiments to test this possibility are investigated on the bases that superfluid Helium vortices would not fall, under the single influence of a uniform gravitational field, at the same rate as the rest of the superfluid Helium mass.

Clovis Jacinto de Matos

2009-09-15T23:59:59.000Z

117

GALAXY SCALE LENSES IN THE RCS2. I. FIRST CATALOG OF CANDIDATE STRONG LENSES  

SciTech Connect

We present the first galaxy scale lens catalog from the second Red-Sequence Cluster Survey. The catalog contains 60 lensing system candidates comprised of Luminous Red Galaxy (LRG) lenses at 0.2 {approx}< z {approx}< 0.5 surrounded by blue arcs or apparent multiple images of background sources. The catalog is a valuable complement to previous galaxy-galaxy lens catalogs as it samples an intermediate lens redshift range and is composed of bright sources and lenses that allow easy follow-up for detailed analysis. Mass and mass-to-light ratio estimates reveal that the lens galaxies are massive ( M-bar {approx} 5.5 Multiplication-Sign 10{sup 11} [M{sub Sun} h{sup -1}]) and rich in dark matter (M/L-bar{approx} 14 [M{sub Sun }/L{sub Sun ,B} h]). Even though a slight increasing trend in the mass-to-light ratio is observed from z = 0.2 to z = 0.5, current redshift and light profile measurements do not allow stringent constraints on the mass-to-light ratio evolution of LRGs.

Anguita, T. [Centro de Astro-Ingenieria, Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile); Barrientos, L. F. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile); Gladders, M. D. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States); Faure, C. [Laboratoire d'Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Obervatoire de Sauverny, CH-1290 Versoix (Switzerland); Yee, H. K. C.; Gilbank, D. G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, Ontario, M5S 3H4 (Canada)

2012-04-01T23:59:59.000Z

118

Gravitational lens magnification by Abell 1689: Distortion of the background galaxy luminosity function  

E-Print Network (OSTI)

Gravitational lensing magnifies the luminosity of galaxies behind the lens. We use this effect to constrain the total mass in the cluster Abell 1689 by comparing the lensed luminosities of background galaxies with the luminosity function of an undistorted field. Since galaxies are assumed to be a random sampling of luminosity space, this method is not limited by clustering noise. We use photometric redshift information to estimate galaxy distance and intrinsic luminosity. Knowing the redshift distribution of the background population allows us to lift the mass/background degeneracy common to lensing analysis. In this paper we use 9 filters observed over 12 hours with the Calar Alto 3.5m telescope to determine the redshifts of 1000 galaxies in the field of Abell 1689. Using a complete sample of 151 background galaxies we measure the cluster mass profile. We find that the total projected mass interior to 0.25h^(-1)Mpc is (0.48 +/- 0.16) * 10^(15)h^(-1) solar masses, where our error budget includes uncertainties from the photometric redshift determination, the uncertainty in the off-set calibration and finite sampling. This result is in good agreement with that found by number count and shear-based methods and provides a new and independent method to determine cluster masses.

S. Dye; A. N. Taylor; E. M. Thommes; K. Meisenheimer; C. Wolf; J. A. Peacock

2000-02-01T23:59:59.000Z

119

Integral-field spectroscopy of SLACS lenses  

E-Print Network (OSTI)

The combination of two-dimensional kinematics and gravitational lens modelling permits detailed reconstruction of the phase-space structure of early-type galaxies and sets constraints on the dark-matter distribution in their inner regions. We describe a project which combines integral-field spectroscopy from an ESO Large Programme using VIMOS on the VLT with deep HST ACS and NICMOS images to study a sample of 17 early-type lens galaxies at redshifts between 0.1 and 0.3, drawn from the Sloan Lens ACS survey (SLACS).

Oliver Czoske; Matteo Barnabe; Leon Koopmans

2008-11-14T23:59:59.000Z

120

Theory of pixel lensing towards M31 I the density contribution and mass of MACHOs  

E-Print Network (OSTI)

POINT-AGAPE is an Anglo-French collaboration which is employing the IsaacNewton Telescope (INT) to conduct a pixel-lensing survey towards M31. In thispaper we investigate what we can learn from pixel-lensing observables about theMACHO mass and fractional contribution in M31 and the Galaxy for the case ofspherically-symmetric near-isothermal haloes. We employ detailed pixel-lensingsimulations which include many of the factors which affect the observables. Fora maximum MACHO halo we predict an event rate in V of up to 100 per season forM31 and 40 per season for the Galaxy. However, the Einstein radius crossingtime is generally not measurable and the observed full-width half-maximumduration provides only a weak tracer of lens mass. Nonetheless, we find thatthe near-far asymmetry in the spatial distribution of M31 MACHOs providessignificant information on their mass and density contribution. We present alikelihood estimator for measuring the fractional contribution and mass of bothM31 and Galaxy MACHOs which perm...

Kerins, E J; Evans, N W; Hewett, P C; Lastennet, E; Le Du, Y; Melchior, A L; Smartt, S J; Valls-Gabaud, D

2000-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Einstein, Black Holes Gravitational Waves  

E-Print Network (OSTI)

1 #12;Einstein, Black Holes and Gravitational Waves Gregory B. Cook Wake Forest University 2 #12 Relativity? · What are some of the consequences of GR? · What are Black Holes like and do they exist? · What? · What are Black Holes like and do they exist? · What can we learn from Gravity Waves? · To do all

Cook, Greg

122

Gravitational Waves from Supersymmetry Breaking  

E-Print Network (OSTI)

In theories of supersymmetry breaking, it is often the case that there is more than one metastable vacuum. First-order phase transitions among such metastable vacua may generate a stochastic background of gravitational waves, the observation of which would provide a direct window into the supersymmetry-breaking sector.

Craig, Nathaniel J

2009-01-01T23:59:59.000Z

123

The Cosmic Lens All-Sky Survey:II. Gravitational lens candidate selection and follow-up  

E-Print Network (OSTI)

We report the final results of the search for gravitationally lensed flat-spectrum radio sources found in the combination of CLASS (Cosmic Lens All Sky Survey) and JVAS (Jodrell-Bank VLA Astrometric Survey). VLA observations of 16,503 sources have been made, resulting in the largest sample of arcsec-scale lens systems available. Contained within the 16,503 sources is a complete sample of 11,685 sources having two-point spectral indices between 1.4 and 5 GHz flatter than -0.5 and 5 GHz flux densities $\\geq$30 mJy. A subset of 8,958 sources form a well-defined statistical sample suitable for analysis of the lens statistics. We describe the systematic process by which 149 candidate lensed sources were picked from the statistical sample on the basis of possessing multiple compact components in the 0.2 arcsec-resolution VLA maps. Candidates were followed up with 0.05 arcsec resolution MERLIN and 0.003 arcsec VLBA observations at 5 GHz and rejected as lens systems if they failed well-defined surface brightness and/or morphological tests. Maps for all the candidates can be found on the World Wide Web at http://www.jb.man.ac.uk/research/gravlens/index.html We summarize the properties of each of the 22 gravitational lens systems in JVAS/CLASS. Twelve are double-image systems, nine are four-image systems and one is a six-image system. Thirteen constitute a statistically well-defined sample giving a point-source lensing rate of 1:690$\\pm$190. The interpretation of the results in terms of the properties of the lensing galaxy population and cosmological parameters will be published elsewhere. (Abridged)

I. W. A. Browne; P. N. Wilkinson; N. J. F. Jackson; S. T. Myers; C. D. Fassnacht; L. V. E. Koopmans; D. R. Marlow; M. Norbury; D. Rusin; C. M. Sykes; A. D. Biggs; R. D. Blandford; A. G. de Bruyn; K-H. Chae; P. Helbig; L. J. King; J. P. McKean; T. J. Pearson; P. M. Phillips; A. C. S. Readhead; E. Xanthopoulos; T. York

2002-11-04T23:59:59.000Z

124

Thermal Gravitational Waves from Primordial Black Holes  

E-Print Network (OSTI)

Thermal gravitational waves can be generated in various sources such as, in the cores of stars, white dwarfs and neutron stars due to the fermion collisions in the dense degenerate Fermi gas. Such high frequency thermal gravitational waves can also be produced during the collisions in a gamma ray burst or during the final stages of the evaporation of primordial black holes. Here we estimate the thermal gravitational waves from primordial black holes and estimate the integrated energy of the gravitational wave emission over the entire volume of the universe and over Hubble time. We also estimate the gravitational wave flux from gamma ray bursts and jets.

C. Sivaram; Kenath Arun

2010-05-19T23:59:59.000Z

125

Constraints on Cosmological Parameters from the Analysis of the Cosmic Lens All Sky Survey Radio-Selected Gravitational Lens Statistics  

E-Print Network (OSTI)

We derive constraints on cosmological parameters and the properties of the lensing galaxies from gravitational lens statistics based on the final Cosmic Lens All Sky Survey (CLASS) data. For a flat universe with a classical cosmological constant, we find that the present matter fraction of the critical density is $\\Omega_{\\rm m}=0.31^{+0.27}_{-0.14}$ (68%) $^{+0.12}_{-0.10}$ (systematic). For a flat universe with a constant equation of state for dark energy $w = p_x({pressure})/\\rho_x({energy density})$, we find $w < -0.55^{+0.18}_{-0.11}$ (68%).

K. -H. Chae; A. D. Biggs; R. D. Blandford; I. W. A. Browne; A. G. de Bruyn; C. D. Fassnacht; P. Helbig; N. J. Jackson; L. J. King; L. V. E. Koopmans; S. Mao; D. R. Marlow; J. P. McKean; S. T. Myers; M. Norbury; T. J. Pearson; P. M. Phillips; A. C. S. Readhead; D. Rusin; C. M. Sykes; P. N. Wilkinson; E. Xanthopoulos; T. York

2002-09-28T23:59:59.000Z

126

Nonadiabatic charged spherical gravitational collapse  

Science Conference Proceedings (OSTI)

We present a complete set of the equations and matching conditions required for the description of physically meaningful charged, dissipative, spherically symmetric gravitational collapse with shear. Dissipation is described with both free-streaming and diffusion approximations. The effects of viscosity are also taken into account. The roles of different terms in the dynamical equation are analyzed in detail. The dynamical equation is coupled to a causal transport equation in the context of Israel-Stewart theory. The decrease of the inertial mass density of the fluid, by a factor which depends on its internal thermodynamic state, is reobtained, with the viscosity terms included. In accordance with the equivalence principle, the same decrease factor is obtained for the gravitational force term. The effect of the electric charge on the relation between the Weyl tensor and the inhomogeneity of the energy density is discussed.

Di Prisco, A.; Herrera, L. [Escuela de Fisica, Facultad de Ciencias, Universidad Central de Venezuela, Caracas (Venezuela); Le Denmat, G. [Universite Pierre et Marie Curie, CNRS/UMR 8112, LERMA/ERGA, Boite 142, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Observatoire de Paris (France); MacCallum, M. A. H. [School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS (United Kingdom); Santos, N. O. [School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS (United Kingdom); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis, Rio de Janeiro (Brazil)

2007-09-15T23:59:59.000Z

127

Hydro-gravitational fragmentation, diffusion and condensation of the primordial plasma, dark-matter and gas  

E-Print Network (OSTI)

The first structures were proto-voids formed in the primordial plasma. Viscous and weak turbulence forces balanced gravitational forces when the scale of causal connection at time 30,000 years matched the viscous and turbulent Schwarz scales of hydro-gravitational theory (Gibson 1996). The photon viscosity allows only weak turbulence from the Reynolds number Re = 200, with fragmentation to give proto-supercluster voids, buoyancy forces, fossil vorticity turbulence, and strong sonic damping. The expanding, cooling, plasma continued fragmentation to proto-galaxy-mass with the density and rate-of-strain preserved as fossils of the weak turbulence and first structure. Turbulence fossilization by self-gravitational buoyancy explains the cosmic microwave background temperature fluctuations, not sonic oscillations in cold-dark-matter fragments. After plasma to gas transition at 300,000 years, gas fragmentation occurred within the proto-galaxies to form proto-globular-star-cluster (PGCs) clouds of small-planetary-mass primordial-fog-particles (PFPs). Dark PGC clumps of frozen PFPs persist as the inner-galaxy-halo dark matter, supporting Schild's 1996 quasar-microlensing interpretation. Non-baryonic dark matter diffused into the plasma proto-cluster-voids and later fragmented as outer-galaxy-halos at diffusive Schwarz scales, indicating light, weakly-collisional fluid particles (possibly neutrinos). Observations support the theory (Gibson and Schild 2003).

Carl H. Gibson

1999-11-15T23:59:59.000Z

128

Weak Energy: Form and Function  

E-Print Network (OSTI)

The equation of motion for a time-independent weak value of a quantum mechanical observable contains a complex valued energy factor - the weak energy of evolution. This quantity is defined by the dynamics of the pre-selected and post-selected states which specify the observable's weak value. It is shown that this energy: (i) is manifested as dynamical and geometric phases that govern the evolution of the weak value during the measurement process; (ii) satisfies the Euler-Lagrange equations when expressed in terms of Pancharatnam (P) phase and Fubini-Study (FS) metric distance; (iii) provides for a PFS stationary action principle for quantum state evolution; (iv) time translates correlation amplitudes; (v) generalizes the temporal persistence of state normalization; and (vi) obeys a time-energy uncertainty relation. A similar complex valued quantity - the pointed weak energy of an evolving state - is also defined and several of its properties in PFS-coordinates are discussed. It is shown that the imaginary part of the pointed weak energy governs the state's survival probability and its real part is - to within a sign - the Mukunda-Simon geometric phase for arbitrary evolutions or the Aharonov-Anandan (AA) phase for cyclic evolutions. Pointed weak energy gauge transformations and the PFS 1-form are discussed and the relationship between the PFS 1-form and the AA connection 1-form is established.

Allen D. Parks

2013-04-09T23:59:59.000Z

129

Energy Conservation at the Gravitational Collapse  

E-Print Network (OSTI)

We apply the principle of energy conservation to the motion of the test particle in gravitational field by requiring that its energy, gained by gravitation, has to be balanced by decrease of its rest mass. Due to the change of mass in gravitational field Newton's force law between gravitating bodies is modified, too. With this modified force law we build up the the classical field theory of gravitation in which all relevant field quantities are in the definition domain $r\\in [0,\\infty)$ finite and positive. We show that under such circumstances, the energy release at any gravitational collapse is finite. On the other side, the energy conservation leads to an equation which relates the mass change of the test particle due to gravitation and the metric of the corresponding gravitational field. The mass change in Newton's gravitational field lead to a remarkable simple metric which shifts, in contrast to the Schwarzschild metric, the horizon of events to the gravity center of the gravitational collapse.

V. Majernik

2006-09-12T23:59:59.000Z

130

Prospect for using fresnel lenses for the concentrating systems of solar installations  

SciTech Connect

The state of development work on Fresnel lenses is reported. The possibility of using them in solar installations is analyzed. It is concluded that Fresnel lenses represent promising optical systems for solar installations.

Lidorenko, N.S.; Zhukov, K.V.; Nabiullin, F.Kh.; Tver' yanovich, E.V.

1977-01-01T23:59:59.000Z

131

Evolution of simple configurations of gravitating gas  

E-Print Network (OSTI)

We considered the dynamics of gravitating gas - a continuous media with peculiar properties. The exact solutions of its Euler equations for simple initial conditions is obtained.

G. P. Pronko

2011-04-23T23:59:59.000Z

132

Precise Gravitational Tests via the SEE Mission: A Proposal for Space-Based Measurements  

E-Print Network (OSTI)

The objective of a SEE mission is to support development of unification theory by carrying out sensitive gravitational tests capable of determining whether various alternative theories are compatible with nature. Gravitation is a key "missing link" in unification theory. Nearly all unification theories incorporate gravity at a fundamental level, and therefore precise measurements of gravitational forces will place important constraints on unification theories. Ground-based gravitational measurements to the accuracy required are impossible due to the many sources of noise present in the terrestrial environment. The proposed space-based Satellite Energy Exchange (SEE) mission will measure several important parameters to an accuracy between 100 and 10,000 times better than current or planned measurement capabilities. It will test for time variation of the gravitational "constant" G and for violations of the weak equivalence principle (WEP) and the inverse-square-law (ISL), and it will determine G. It is well-known that the discovery of breakdowns in WEP or ISL and the possible determination of a time-varying G would have significant consequences on virtually all aspects of unification theory.

Alvin J. Sanders; George T. Gillies

2010-05-20T23:59:59.000Z

133

VLBI phase-reference observations of the gravitational lens JVAS B0218+357  

E-Print Network (OSTI)

We present the results of phase-referenced VLBA+Effelsberg observations at five frequencies of the double-image gravitational lens JVAS B0218+357, made to establish the precise registration of the A and B lensed image positions. The motivation behind these observations is to investigate the anomalous variation of the image flux density ratio (A/B) with frequency - this ratio changes by almost a factor of two over a frequency range from 1.65 GHz to 15.35 GHz. We investigate whether frequency dependent image positions, combined with a magnification gradient across the image field, could give rise to the anomaly. Our observations confirm the variation of image flux ratio with frequency. The results from our phase-reference astrometry, taken together with the lens mass model of Wucknitz et al. (2004), show that shifts of the image peaks and centroids are too small to account for the observed frequency-dependent ratio.

Rupal Mittal; Richard Porcas; Olaf Wucknitz; Andy Biggs; Ian Browne

2005-08-09T23:59:59.000Z

134

Optimal filling factor of nanorod lenses for subwavelength imaging  

SciTech Connect

We analyze the effect of the filling factor on the imaging performance of metallic nanorod lenses. We observe that thicker nanorods allow lower reflection in the canalization regime and we find optimal values of the filling factor to achieve a transfer function with the characteristics of a perfect lens in a wide range of spatial frequencies.

Kosulnikov, Sergey Yu.; Yankovskaya, Elizaveta A. [Department of Photonics and Optoinformatics, St. Petersburg National Research University of Information Technologies, Mechanics and Optics, Kronverkskiy pr., 49, 197101 St. Petersburg (Russian Federation); Maslovski, Stanislav I. [Department of Electrical Engineering, Instituto de Telecomunicacoes, Universidade de Coimbra, Polo II, 3030-290 Coimbra (Portugal); Belov, Pavel A. [Department of Photonics and Optoinformatics, St. Petersburg National Research University of Information Technologies, Mechanics and Optics, Kronverkskiy pr., 49, 197101 St. Petersburg (Russian Federation); Queen Mary College, University of London, Mile End Road, London E1 4NS (United Kingdom); Kivshar, Yuri S. [Department of Photonics and Optoinformatics, St. Petersburg National Research University of Information Technologies, Mechanics and Optics, Kronverkskiy pr., 49, 197101 St. Petersburg (Russian Federation); School of Electronic Engineering and Computer Science, Nonlinear Physics Centre, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

2011-12-15T23:59:59.000Z

135

Large photon productions in a gravitational collapsing  

E-Print Network (OSTI)

We study a possible gravitational vacuum-effect, in which vacuum-energy variation is due to variation of gravitational field, vacuum state gains gravitational energy and releases it by spontaneous photon emissions. Based on the path-integral representation, we present a general formulation of vacuum transition matrix and energy-momentum tensor of a quantum scalar field theory in curved spacetime. Using analytical continuation of dimensionality of the phase space, we calculate the difference of vacuum-energy densities in the presence and absence of gravitational field. Using the dynamical equation of gravitational collapse, we compute the rate of vacuum state gaining gravitational energy. Computing the transition amplitude from initial vacuum state to final vacuum state in gravitational collapsing process, we show the rate and spectrum of spontaneous photon emissions for releasing gravitational energy. The possible connection of our study to the genuine origin of gamma ray bursts is discussed. We compare our idea with the Schwinger idea for Sonoluminiescence and contrast our scenario with the Hawking effect.

She-Sheng Xue

2002-05-09T23:59:59.000Z

136

Interaction of light with gravitational waves  

E-Print Network (OSTI)

The physical properties of electromagnetic waves in the presence of a gravitational plane wave are analyzed. Formulas for the Stokes parameters describing the polarization of light are obtained in closed form. The particular case of a constant amplitude gravitational wave is worked out explicitly.

Shahen Hacyan

2013-05-20T23:59:59.000Z

137

Gravitational Binary-lens Events with Prominent Effects of Lens Orbital Motion  

E-Print Network (OSTI)

Gravitational microlensing events produced by lenses composed of binary masses are important because they provide a major channel to determine physical parameters of lenses. In this work, we analyze the light curves of two binary-lens events OGLE-2006-BLG-277 and OGLE-2012-BLG-0031 for which the light curves exhibit strong deviations from standard models. From modeling considering various second-order effects, we find that the deviations are mostly explained by the effect of the lens orbital motion. We also find that lens parallax effects can mimic orbital effects to some extent. This implies that modeling light curves of binary-lens events not considering orbital effects can result in lens parallaxes that are substantially different from actual values and thus wrong determinations of physical lens parameters. This demonstrates the importance of routine consideration of orbital effects in interpreting light curves of binary-lens events. It is found that the lens of OGLE-2006-BLG-277 is a binary composed of a ...

Park, H; Han, C; Gould, A; Beaulieu, J -P; Tsapras, Y; Szyma?ski, M K; Kubiak, M; Soszy?ski, I; Pietrzy?ski, G; Poleski, R; Ulaczyk, K; Pietrukowicz, P; Koz?owski, S; Skowron, J; Wyrzykowski, ?; Choi, J -Y; Depoy, D L; Dong, Subo; Gaudi, B S; Hwang, K -H; Jung, Y K; Kavka, A; Lee, C -U; Monard, L A G; Park, B -G; Pogge, R W; Porritt, I; Shin, I -G; Yee, J C; Albrow, M D; Bennett, D P; Caldwell, J A R; Cassan, A; Coutures, C; Dominis, D; Donatowicz, J; Fouqué, P; Greenhill, J; Huber, M; Jřrgensen, U G; Kane, S; Kubas, D; Marquette, J -B; Menzies, J; Pitrou, C; Pollard, K R; Sahu, K C; Wambsganss, J; Williams, A; Zub, M; Allan, A; Bramich, D M; Browne, P; Dominik, M; Horne, K; Hundertmark, M; Kains, N; Snodgrass, C; Steele, I A; Street, R A

2013-01-01T23:59:59.000Z

138

MERLIN/VLA imaging of the gravitational lens system B0218+357  

E-Print Network (OSTI)

Gravitational lenses offer the possibility of accurately determining the Hubble parameter (H_0) over cosmological distances, and B0218+357 is one of the most promising systems for an application of this technique. In particular this system has an accurately measured time delay (10.5+/-0.4 d; Biggs et al. 1999) and preliminary mass modelling has given a value for H_0 of 69 +13/-19 km/s/Mpc. The error on this estimate is now dominated by the uncertainty in the mass modelling. As this system contains an Einstein ring it should be possible to constrain the model better by imaging the ring at high resolution. To achieve this we have combined data from MERLIN and the VLA at a frequency of 5 GHz. In particular MERLIN has been used in multi-frequency mode in order to improve substantially the aperture coverage of the combined data set. The resulting map is the best that has been made of the ring and contains many new and interesting features. Efforts are currently underway to exploit the new data for lensing constraints using the LensClean algorithm (Kochanek & Narayan 1992).

A. D. Biggs; I. W. A. Browne; T. W. B. Muxlow; P. N. Wilkinson

2000-11-07T23:59:59.000Z

139

Constraining gravitational and cosmological parameters with astrophysical data  

E-Print Network (OSTI)

We use astrophysical data to shed light on fundamental physics by constraining parametrized theoretical cosmological and gravitational models. Gravitational parameters are those constants that parametrize possible departures ...

Mao, Yi, Ph. D. Massachusetts Institute of Technology

2008-01-01T23:59:59.000Z

140

Detectability of gravitational waves from phase transitions  

Science Conference Proceedings (OSTI)

Gravitational waves potentially represent our only direct probe of the universe when it was less than one second old. In particular, first-order phase transitions in the early universe can generate a stochastic background of gravitational waves which may be detectable today. We briefly summarize the physical sources of gravitational radiation from phase transitions and present semianalytic expressions for the resulting gravitational wave spectra from three distinct realistic sources: bubble collisions, turbulent plasma motions, and inverse-cascade helical magnetohydrodynamic turbulence. Using phenomenological parameters to describe phase transition properties, we determine the region of parameter space for which gravitational waves can be detected by the proposed Laser Interferometer Space Antenna. The electroweak phase transition is detectable for a wide range of parameters.

Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); CCPP, New York University, 4 Washington Plaza, New York, New York 10003 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Kosowsky, Arthur [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, Pennsylvania 15260 (United States); Gogoberidze, Grigol [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Maravin, Yurii [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

2008-08-15T23:59:59.000Z

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141

Cobordisms to weakly splittable links  

E-Print Network (OSTI)

We show that if a link L with non-zero Alexander polynomial admits a locally flat cobordism to a `weakly m-split link', then the cobordism must have genus at least (m-1)/2. This generalises a recent result of J. Pardon.

Friedl, Stefan

2011-01-01T23:59:59.000Z

142

A test of Einstein's theory of gravitation: Velocity distribution of low-energy particles in a spherically symmetric gravitational field  

E-Print Network (OSTI)

We propose a new test of Einstein's theory of gravitation. It concerns the velocity distribution of low-energy particles in a spherically symmetric gravitational field.

Jian-Miin Liu

2002-06-17T23:59:59.000Z

143

BE condensates of weakly interacting bosons in gravity fields  

E-Print Network (OSTI)

The Bose-Einstein (BE) condensates of weakly interacting bosons in a strong gravity field, such as AGN (Active Galactic Nuclei), BHs (black holes) and neutron stars, are discussed. Being bound systems in gravity fields, these are stable reservoirs for the Higgs bosons, and vector bosons of Z and W as well as supersymmetric bosons. Upon gravitational disturbances, such as a gravitational collapse, these objects are relieved from the BE condensate bound states and decay or interact with each other freely. Using the repulsive nature of gravity at short distances which was obtained by the present author as quantum corrections to gravity, the particles produced by the decays or interactions of the bosons liberated from BE condensates can be emitted outside the horizon for our observation. It is suggested that the recently observed gamma ray peak at 129.8 +- 2.4 GeV from FERMI Large Area Telescope may be evidence for the existence of the Higgs boson condensates. The BE condensates of supersymmetric bosons are the most likely sources for the gamma rays from DMP (dark matter particle) and anti-DMP collisions. It is shown that the said process from DMPs spread in the galaxy is too small for the incident DMP with the intensity of the cosmic ray energy spectrum.

Yukio Tomozawa

2012-11-21T23:59:59.000Z

144

Subtraction-noise projection in gravitational-wave detector networks  

SciTech Connect

In this paper, we present a successful implementation of a subtraction-noise projection method into a simple, simulated data analysis pipeline of a gravitational-wave search. We investigate the problem to reveal a weak stochastic background signal which is covered by a strong foreground of compact-binary coalescences. The foreground, which is estimated by matched filters, has to be subtracted from the data. Even an optimal analysis of foreground signals will leave subtraction noise due to estimation errors of template parameters which may corrupt the measurement of the background signal. The subtraction noise can be removed by a noise projection. We apply our analysis pipeline to the proposed future-generation space-borne Big Bang Observer mission which seeks for a stochastic background of primordial gravitational waves in the frequency range {approx}0.1 Hz--1 Hz covered by a foreground of black-hole and neutron-star binaries. Our analysis is based on a simulation code which provides a dynamical model of a time-delay interferometer network. It generates the data as time series and incorporates the analysis pipeline together with the noise projection. Our results confirm previous ad hoc predictions which say that the Big Bang Observer will be sensitive to backgrounds with fractional energy densities below {omega}=10{sup -16}.

Harms, Jan; Mahrdt, Christoph; Otto, Markus; Priess, Malte [Institut fuer Gravitationsphysik, Universitaet Hannover and Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Callinstrasse 38, 30167 Hannover (Germany)

2008-06-15T23:59:59.000Z

145

Hydro-Gravitational-Dynamics of Planets and Dark Energy  

E-Print Network (OSTI)

Self-gravitational fluid mechanical methods termed hydro-gravitational-dynamics (HGD) predict plasma fragmentation 0.03 Myr after the turbulent big bang to form protosuperclustervoids, turbulent protosuperclusters, and protogalaxies at the 0.3 Myr transition from plasma to gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscous-inertial scales along turbulent vortex lines or in spirals, as observed. The plasma protogalaxies fragment on transition into white-hot planet-mass gas clouds (PFPs) in million-solar-mass clumps (PGCs) that become globular-star-clusters (GCs) from tidal forces or dark matter (PGCs) by freezing and diffusion into 0.3 Mpc halos with 97% of the galaxy mass. The weakly collisional non-baryonic dark matter diffuses to > Mpc scales and frag-ments to form galaxy cluster halos. Stars and larger planets form by binary mergers of the trillion PFPs per PGC on 0.03 Mpc galaxy accretion disks. Star deaths depend on rates of planet accretion and internal star mixing. Moderate accretion rates p...

Gibson, Carl H

2008-01-01T23:59:59.000Z

146

Search for Gravitational Waves from Intermediate Mass Binary Black Holes  

E-Print Network (OSTI)

We present the results of a weakly modeled burst search for gravitational waves from mergers of non-spinning intermediate mass black holes (IMBH) in the total mass range 100--450 solar masses and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the IMBH mergers as a function of the component masses. In the most efficiently detected bin centered on 88+88 solar masses, for non-spinning sources, the rate density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.

the LIGO Scientific Collaboration; the Virgo Collaboration; J. Abadie; B. P. Abbott; R. Abbott; T. D. Abbott; M. Abernathy; T. Accadia; F. Acernese; C. Adams; R. Adhikari; C. Affeldt; M. Agathos; K. Agatsuma; P. Ajith; B. Allen; E. Amador Ceron; D. Amariutei; S. B. Anderson; W. G. Anderson; K. Arai; M. A. Arain; M. C. Araya; S. M. Aston; P. Astone; D. Atkinson; P. Aufmuth; C. Aulbert; B. E. Aylott; S. Babak; P. Baker; G. Ballardin; S. Ballmer; J. C. B. Barayoga; D. Barker; F. Barone; B. Barr; L. Barsotti; M. Barsuglia; M. A. Barton; I. Bartos; R. Bassiri; M. Bastarrika; A. Basti; J. Batch; J. Bauchrowitz; Th. S. Bauer; M. Bebronne; D. Beck; B. Behnke; M. Bejger; M. G. Beker; A. S. Bell; A. Belletoile; I. Belopolski; M. Benacquista; J. M. Berliner; A. Bertolini; J. Betzwieser; N. Beveridge; P. T. Beyersdorf; I. A. Bilenko; G. Billingsley; J. Birch; R. Biswas; M. Bitossi; M. A. Bizouard; E. Black; J. K. Blackburn; L. Blackburn; D. Blair; B. Bland; M. Blom; O. Bock; T. P. Bodiya; C. Bogan; R. Bondarescu; F. Bondu; L. Bonelli; R. Bonnand; R. Bork; M. Born; V. Boschi; S. Bose; L. Bosi; B. Bouhou; S. Braccini; C. Bradaschia; P. R. Brady; V. B. Braginsky; M. Branchesi; J. E. Brau; J. Breyer; T. Briant; D. O. Bridges; A. Brillet; M. Brinkmann; V. Brisson; M. Britzger; A. F. Brooks; D. A. Brown; T. Bulik; H. J. Bulten; A. Buonanno; J. Burguet-Castell; D. Buskulic; C. Buy; R. L. Byer; L. Cadonati; G. Cagnoli; E. Calloni; J. B. Camp; P. Campsie; J. Cannizzo; K. Cannon; B. Canuel; J. Cao; C. D. Capano; F. Carbognani; L. Carbone; S. Caride; S. Caudill; M. Cavaglia; F. Cavalier; R. Cavalieri; G. Cella; C. Cepeda; E. Cesarini; O. Chaibi; T. Chalermsongsak; P. Charlton; E. Chassande-Mottin; S. Chelkowski; W. Chen; X. Chen; Y. Chen; A. Chincarini; A. Chiummo; H. Cho; J. Chow; N. Christensen; S. S. Y. Chua; C. T. Y. Chung; S. Chung; G. Ciani; F. Clara; D. E. Clark; J. Clark; J. H. Clayton; F. Cleva; E. Coccia; P. -F. Cohadon; C. N. Colacino; J. Colas; A. Colla; M. Colombini; A. Conte; R. Conte; D. Cook; T. R. Corbitt; M. Cordier; N. Cornish; A. Corsi; C. A. Costa; M. Coughlin; J. -P. Coulon; P. Couvares; D. M. Coward; M. Cowart; D. C. Coyne; J. D. E. Creighton; T. D. Creighton; A. M. Cruise; A. Cumming; L. Cunningham; E. Cuoco; R. M. Cutler; K. Dahl; S. L. Danilishin; R. Dannenberg; S. D'Antonio; K. Danzmann; V. Dattilo; B. Daudert; H. Daveloza; M. Davier; E. J. Daw; R. Day; T. Dayanga; R. De Rosa; D. DeBra; G. Debreczeni; W. Del Pozzo; M. del Prete; T. Dent; V. Dergachev; R. DeRosa; R. DeSalvo; S. Dhurandhar; L. Di Fiore; A. Di Lieto; I. Di Palma; M. Di Paolo Emilio; A. Di Virgilio; M. Diaz; A. Dietz; F. Donovan; K. L. Dooley; M. Drago; R. W. P. Drever; J. C. Driggers; Z. Du; J. -C. Dumas; S. Dwyer; T. Eberle; M. Edgar; M. Edwards; A. Effler; P. Ehrens; G. Endroczi; R. Engel; T. Etzel; K. Evans; M. Evans; T. Evans; M. Factourovich; V. Fafone; S. Fairhurst; Y. Fan; B. F. Farr; D. Fazi; H. Fehrmann; D. Feldbaum; F. Feroz; I. Ferrante; F. Fidecaro; L. S. Finn; I. Fiori; R. P. Fisher; R. Flaminio; M. Flanigan; S. Foley; E. Forsi; L. A. Forte; N. Fotopoulos; J. -D. Fournier; J. Franc; S. Frasca; F. Frasconi; M. Frede; M. Frei; Z. Frei; A. Freise; R. Frey; T. T. Fricke; D. Friedrich; P. Fritschel; V. V. Frolov; M. -K. Fujimoto; P. J. Fulda; M. Fyffe; J. Gair; M. Galimberti; L. Gammaitoni; J. Garcia; F. Garufi; M. E. Gaspar; G. Gemme; R. Geng; E. Genin; A. Gennai; L. A. Gergely; S. Ghosh; J. A. Giaime; S. Giampanis; K. D. Giardina; A. Giazotto; S. Gil; C. Gill; J. Gleason; E. Goetz; L. M. Goggin; G. Gonzalez; M. L. Gorodetsky; S. Gossler; R. Gouaty; C. Graef; P. B. Graff; M. Granata; A. Grant; S. Gras; C. Gray; N. Gray; R. J. S. Greenhalgh; A. M. Gretarsson; C. Greverie; R. Grosso; H. Grote; S. Grunewald; G. M. Guidi; C. Guido; R. Gupta; E. K. Gustafson; R. Gustafson; T. Ha; J. M. Hallam; D. Hammer; G. Hammond; J. Hanks; C. Hanna; J. Hanson; J. Harms; G. M. Harry; I. W. Harry; E. D. Harstad; M. T. Hartman; K. Haughian; K. Hayama; J. -F. Hayau; J. Heefner; A. Heidmann; M. C. Heintze; H. Heitmann; P. Hello; M. A. Hendry; I. S. Heng; A. W. Heptonstall; V. Herrera; M. Hewitson; S. Hild; D. Hoak; K. A. Hodge; K. Holt; M. Holtrop; T. Hong; S. Hooper; D. J. Hosken; J. Hough; E. J. Howell; B. Hughey; S. Husa; S. H. Huttner; T. Huynh-Dinh; D. R. Ingram; R. Inta; T. Isogai; A. Ivanov; K. Izumi; M. Jacobson; E. James; Y. J. Jang; P. Jaranowski; E. Jesse; W. W. Johnson; D. I. Jones; G. Jones; R. Jones; L. Ju; P. Kalmus; V. Kalogera; S. Kandhasamy; G. Kang; J. B. Kanner; R. Kasturi; E. Katsavounidis; W. Katzman; H. Kaufer; K. Kawabe; S. Kawamura; F. Kawazoe; D. Kelley; W. Kells; D. G. Keppel; Z. Keresztes; A. Khalaidovski; F. Y. Khalili; E. A. Khazanov; B. Kim; C. Kim; H. Kim; K. Kim; N. Kim; Y. -M. Kim; P. J. King; D. L. Kinzel; J. S. Kissel; S. Klimenko; K. Kokeyama; V. Kondrashov; S. Koranda; W. Z. Korth; I. Kowalska

2012-01-28T23:59:59.000Z

147

Search for Gravitational Waves from Intermediate Mass Binary Black Holes  

E-Print Network (OSTI)

We present the results of a weakly modeled burst search for gravitational waves from mergers of non-spinning intermediate mass black holes (IMBH) in the total mass range 100--450 solar masses and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the IMBH mergers as a function of the component masses. In the most efficiently detected bin centered on 88+88 solar masses, for non-spinning sources, the rate density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.

Abadie, J; Abbott, R; Abbott, T D; Abernathy, M; Accadia, T; Acernese, F; Adams, C; Adhikari, R; Affeldt, C; Agathos, M; Agatsuma, K; Ajith, P; Allen, B; Ceron, E Amador; Amariutei, D; Anderson, S B; Anderson, W G; Arai, K; Arain, M A; Araya, M C; Aston, S M; Astone, P; Atkinson, D; Aufmuth, P; Aulbert, C; Aylott, B E; Babak, S; Baker, P; Ballardin, G; Ballmer, S; Baragoya, J C B; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Bastarrika, M; Basti, A; Batch, J; Bauchrowitz, J; Bauer, Th S; Bebronne, M; Beck, D; Behnke, B; Bejger, M; Beker, M G; Bell, A S; Belletoile, A; Belopolski, I; Benacquista, M; Berliner, J M; Bertolini, A; Betzwieser, J; Beveridge, N; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Birch, J; Biswas, R; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bland, B; Blom, M; Bock, O; Bodiya, T P; Bogan, C; Bondarescu, R; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, S; Bosi, L; Bouhou, B; Braccini, S; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Breyer, J; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Bulik, T; Bulten, H J; Buonanno, A; Burguet-Castell, J; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Calloni, E; Camp, J B; Campsie, P; Cannizzo, J; Cannon, K; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Caudill, S; Cavaglia, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chaibi, O; Chalermsongsak, T; Charlton, P; Chassande-Mottin, E; Chelkowski, S; Chen, W; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H; Chow, J; Christensen, N; Chua, S S Y; Chung, C T Y; Chung, S; Ciani, G; Clark, D E; Clark, J; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P -F; Colacino, C N; Colas, J; Colla, A; Colombini, M; Conte, A; Conte, R; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corsi, A; Costa, C A; Coughlin, M; Coulon, J -P; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Creighton, J D E; Creighton, T D; Cruise, A M; Cumming, A; Cunningham, L; Cuoco, E; Cutler, R M; Dahl, K; Danilishin, S L; Dannenberg, R; D'Antonio, S; Danzmann, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Daw, E J; Day, R; Dayanga, T; De Rosa, R; DeBra, D; Debreczeni, G; Del Pozzo, W; del Prete, M; Dent, T; Dergachev, V; DeRosa, R; DeSalvo, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Emilio, M Di Paolo; Di Virgilio, A; Diaz, M; Dietz, A; Donovan, F; Dooley, K L; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dumas, J -C; Eberle, T; Edgar, M; Edwards, M; Effler, A; Ehrens, P; Endroczi, G; Engel, R; Etzel, T; Evans, K; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, Y; Farr, B F; Fazi, D; Fehrmann, H; Feldbaum, D; Feroz, F; Ferrante, I; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Flanigan, M; Foley, S; Forsi, E; Forte, L A; Fotopoulos, N; Fournier, J -D; Franc, J; Frasca, S; Frasconi, F; Frede, M; Frei, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Friedrich, D; Fritschel, P; Frolov, V V; Fujimoto, M -K; Fulda, P J; Fyffe, M; Gair, J; Galimberti, M; Gammaitoni, L; Garcia, J; Garufi, F; Gaspar, M E; Gemme, G; Geng, R; Genin, E; Gennai, A; Gergely, L A; Ghosh, S; Giaime, J A; Giampanis, S; Giardina, K D; Giazotto, A; Gil, S; Gill, C; Gleason, J; Goetz, E; Goggin, L M; Gonzalez, G; Gorodetsky, M L; Gossler, S; Gouaty, R; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Gray, N; Greenhalgh, R J S; Gretarsson, A M; Greverie, C; Grosso, R; Grote, H; Grunewald, S; Guidi, G M; Gupta, R; Gustafson, E K; Gustafson, R; Ha, T; Hallam, J M; Hammer, D; Hammond, G; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hartman, M T; Haughian, K; Hayama, K; Hayau, J -F; Heefner, J; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hendry, M A; Heng, I S; Heptonstall, A W; Herrera, V; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Holtrop, M; Hong, T; Hooper, S; Hosken, D J; Hough, J; Howell, E J; Hughey, B; Husa, S; Huttner, S H; Inta, R; Isogai, T; Ivanov, A; Izumi, K; Jacobson, M; James, E; Jang, Y J; Jaranowski, P; Jesse, E; Johnson, W W; Jones, D I; Jones, G; Jones, R; Ju, L; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kasturi, R; Katsavounidis, E; Katzman, W; Kaufer, H; Kawabe, K; Kawamura, S; Kawazoe, F; Kelley, D; Kells, W; Keppel, D G; Keresztes, Z; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, B; Kim, C; Kim, H; Kim, K; Kim, N; Kim, Y -M; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D; Kranz, O; Kringel, V; Krishnamurthy, S; Krishnan, B; Krolak, A; Kuehn, G; Kumar, R; Kwee, P; Lam, P K; Landry, M; Lantz, B; Lastzka, N; Lawrie, C; Lazzarini, A; Leaci, P; Lee, C H; Lee, H K; Lee, H M; Leong, J R; Leonor, I; Leroy, N; Letendre, N; Li, J

2012-01-01T23:59:59.000Z

148

Gravitational waves with distinct wavefronts  

E-Print Network (OSTI)

Exact solutions of Einstein's vacuum equations are considered which describe gravitational waves with distinct wavefronts. A family of such solutions presented recently in which the wavefronts have various geometries and which propagate into a number of physically significant backgrounds is here related to an integral representation which is a generalisation of the Rosen pulse solution for cylindrical waves. A nondiagonal solution is also constructed which is a generalisation of the Rosen pulse, being a cylindrical pulse wave with two states of polarization propagating into a Minkowski background. The solution is given in a complete and explicit form. A further generalisation to include electromagnetic waves with a distinct wavefront of the same type is also discussed.

G A Alekseev; J B Griffiths

1997-07-22T23:59:59.000Z

149

Self-gravitating branes again  

E-Print Network (OSTI)

We raise on theoretical grounds the question of the physical relevance of Israel matching conditions and their generalizations to higher codimensions, the standard cornerstone of the braneworld and other membrane scenarios. Our reasoning is twofold: First, the incapability of the conventional matching conditions to accept the Nambu-Goto probe limit (even the geodesic limit of the Israel matching conditions is not acceptable since being the geodesic equation a kinematical fact it should be preserved for all gravitational theories or defects, which is not the case for these conditions). Second, in our D-dimensional spacetime (maybe D=4), classical defects of any possible codimension should be compatible. These matching conditions fail to accept codimension-2 and 3 defects for D=4 (which represents effectively the spacetime at certain length and energy scales) and most probably fail to accept high enough codimensional defects for any D since there is no high enough Lovelock density to support them. Here, we propose alternative matching conditions which seem to satisfy the previous criteria. Instead of varying the brane-bulk action with respect to the bulk metric at the brane position, we vary with respect to the brane embedding fields so that the gravitational back-reaction is included. For a codimension-2 brane in 6-dim EGB gravity we prove its consistency for an axially symmetric cosmological configuration. The cosmologies found have the LFRW behaviour and extra correction terms. For a radiation brane one solution avoids a cosmological singularity and undergoes accelerated expansion near the minimum scale factor. In the presence of an induced gravity term, there naturally appears in the theory the effective cosmological constant scale lambda/(M_6^4 r_c^2), which for a brane tension lambda\\sim M_6^4 (e.g. TeV^4) and r_c \\sim H_0^{-1} gives the observed value of the cosmological constant.

Georgios Kofinas; Maria Irakleidou

2013-09-03T23:59:59.000Z

150

Bending of Light Near a Star and Gravitational Red/Blue Shift : Alternative Explanation Based on Refraction of Light  

E-Print Network (OSTI)

Many of the general-relativity-tests such as bending of light near a star and gravitational red/blue shift are explained without general-relativity and without Newtonian-approach. The author first casts doubts on both, the Newtonian and the relativistic approach; and proposes a novel alternative-explanation. The new alternative-explanation is based on refraction-phenomenon of optics. It predicts that as the ray passes through/near the stars atmospheric-medium, it bends due to refraction-phenomenon towards star-core, like a ray bends while passing through a prism or water-drop. A semi-empirical estimation of the atmospheric-height and its refractive-index are made to find the refraction-results. The refraction-based theory also suggests new explanation for gravitational red/blue shift; it tells that frequency remains constant (as it is so in refraction-phenomenon) and the red/blue shift is due to change in wavelength due to change in velocity of light in the medium . Estimated results for bending of light and the red/blue shift etc. with the new approach though agree well with known values, but important thing is that the physics is quite different. The proposed refraction-based theory proposes a new-look on black-hole, suggesting that black-hole formation is critically due to total-internal-reflection within atmosphere and subsequent absorption into the star-core. Gravitational-lensing is explained as real refraction-lensing. The present paper also suggests a possible-alternative and meaning to the curved geometry of space-time, and indicates that the fabric of space-time which warps(curves) around the mass is not the empty-vacuum but the atmospheric-medium.

Dr. R. C. Gupta

2004-09-24T23:59:59.000Z

151

Renormalized weak plasma turbulence theory  

SciTech Connect

A renormalized Vlasov turbulence theory, derived by neglecting a mode coupling term in the Direct Interaction Approximation, is discussed. The theory reduces correctly to weak turbulence theory; it predicts both diffusion and polarization effects of the turbulent medium on test particles, as well as the inverse effects of the test particles on the medium. A heuristic, physical algorithm is presented for constructing the equations. The theory of the renormalized dielectric function is reviewed.

Krommes, J.A.; Kleva, R.G.

1979-02-01T23:59:59.000Z

152

Linking electroweak and gravitational generators  

E-Print Network (OSTI)

Using complexified quaternions, an intriguing link between generators of two different and surprisingly commuting four-dimensional representations of the SU(2)xU(1) Lie group, and generators of two four-dimensional spin 1/2 representations of the Spin(3,1) Lie group is established: the former generators completely determine the latter ones, and cross-combined they constitute two different, but closely related, four-dimensional representations of Spin(3,1)xSU(2)xU(1). These representations are used to construct a Spin(3,1)xSU(2)xU(1) gauge invariant Lagrangian, containing two four-spinors consisting not as usual of Weyl two-spinors of opposite helicity and equal weak isospin, but instead of Weyl two-spinors of opposite weak isospin and equal helicity, a construction which arises naturally from the mathematical formalism itself. A possible future generalization, using complexified octonions, is discussed.

John Fredsted

2007-12-14T23:59:59.000Z

153

On Amplification by Weak Measurement  

E-Print Network (OSTI)

We analyze the amplification by the Aharonov-Albert-Vaidman weak quantum measurement on a Sagnac interferometer [P. B. Dixon et al., Phys. Rev. Lett. 102, 173601 (2009)] up to all orders of the coupling strength between the measured system and the measuring device. The amplifier transforms a small tilt of a mirror into a large transverse displacement of the laser beam. The conventional analysis has shown that the measured value is proportional to the weak value, so that the amplification can be made arbitrarily large in the cost of decreasing output laser intensity. It is shown that the measured displacement and the amplification factor are in fact not proportional to the weak value and rather vanish in the limit of infinitesimal output intensity. We derive the optimal overlap of the pre- and post-selected states with which the amplification become maximum. We also show that the nonlinear effects begin to arise in the performed experiments so that any improvements in the experiment, typically with an amplification greater than 100, should require the nonlinear theory in translating the observed value to the original displacement.

Tatsuhiko Koike; Saki Tanaka

2011-08-09T23:59:59.000Z

154

Ultraviolet structure in the lensed QSOs 0957+561  

E-Print Network (OSTI)

Imaging and spectra of the lensed QSO pair 0957+561 are presented and discussed. The data are principally those from the STIS NUV MAMA, and cover rest wavelengths from 850A to 1350A. The QSOs are both extended over about 1 arcsec, with morphology that matches with a small rotation, and includes one feature aligned with the VLBI radio jets. This is the first evidence of lensed structure in the host galaxy. The off-nuclear spectra arise from emission line gas and a young stellar population. The gas has velocity components with radial velocities at least 1000 km/s with respect to the QSO BLR, and may be related to the damped Ly alpha absorber in the nuclear spectra.

J. B. Hutchings

2003-03-24T23:59:59.000Z

155

Spectrum of gravitational radiation from primordial turbulence  

Science Conference Proceedings (OSTI)

Energy injection into the early universe can induce turbulent motions of the primordial plasma, which in turn act as a source for gravitational radiation. Earlier work computed the amplitude and characteristic frequency of the relic gravitational wave background, as a function of the total energy injected and the stirring scale of the turbulence. This paper computes the frequency spectrum of relic gravitational radiation from a turbulent source of the stationary Kolmogoroff form which acts for a given duration, making no other approximations. We also show that the limit of long source wavelengths, commonly employed in aeroacoustic problems, is an excellent approximation. The gravitational waves from cosmological turbulence around the electroweak energy scale will be detectable by future space-based laser interferometers for a substantial range of turbulence parameters.

Gogoberidze, Grigol [Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, GE-0160 Tbilisi (Georgia); Kahniashvili, Tina [Center for Cosmology and Particle Physics, New York University, 4 Washington Plaza, New York, New York 10003 (United States); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, GE-0160 Tbilisi (Georgia); Kosowsky, Arthur [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, Pennsylvania 15260 (United States)

2007-10-15T23:59:59.000Z

156

Biased Weak Polyform Achievement Games  

E-Print Network (OSTI)

In a biased weak $(a,b)$ polyform achievement game, the maker and the breaker alternately mark $a,b$ previously unmarked cells on an infinite board, respectively. The maker's goal is to mark a set of cells congruent to a polyform. The breaker tries to prevent the maker from achieving this goal. A winning maker strategy for the $(a,b)$ game can be built from winning strategies for games involving fewer marks for the maker and the breaker. A new type of breaker strategy called the priority strategy is introduced. The winners are determined for all $(a,b)$ pairs for polyiamonds and polyominoes up to size four.

Norris, Ian

2011-01-01T23:59:59.000Z

157

Electromagnetic weak turbulence theory revisited  

SciTech Connect

The statistical mechanical reformulation of weak turbulence theory for unmagnetized plasmas including fully electromagnetic effects was carried out by Yoon [Phys. Plasmas 13, 022302 (2006)]. However, the wave kinetic equation for the transverse wave ignores the nonlinear three-wave interaction that involves two transverse waves and a Langmuir wave, the incoherent analogue of the so-called Raman scattering process, which may account for the third and higher-harmonic plasma emissions. The present paper extends the previous formalism by including such a term.

Yoon, P. H. [IPST, University of Maryland, College Park, Maryland 20742 (United States); Ziebell, L. F. [Instituto de Fisica, UFRGS, Porto Alegre, RS (Brazil); Gaelzer, R.; Pavan, J. [Instituto de Fisica e Matematica, UFPel, Pelotas, RS (Brazil)

2012-10-15T23:59:59.000Z

158

A Master Equation for Gravitational Decoherence: Probing the Textures of Spacetime  

E-Print Network (OSTI)

We give a first principles derivation of a master equation for the evolution of a quantum matter field in a linearly perturbed Minkowski spacetime, based solely on quantum field theory and general relativity. We make no additional assumptions nor introduce extra ingredients, as is often done in alternative quantum theories. When the quantum matter field is projected to a one-particle state, the master equation for a non-relativistic quantum particle in a weak gravitational field predicts decoherence in the energy basis, in contrast to most existing theories of gravitational decoherence. We point out the gauge nature of time and space reparameterizations in matter-gravity couplings, and warn that `intrinsic' decoherence or alternative quantum theories invoking stochastic dynamics arising from temporal or spatial fluctuations violate this fundamental symmetry of classical general relativity. Interestingly we find that the decoherence rate depends on extra parameters other than the Planck scale, an important feature of gravitational decoherence. This is similar to the dependence of the decoherence rate of a quantum Brownian particle to the temperature and spectral density of the environment it interacts with. The corresponding features when gravity acts as an environment in decohering quantum objects are what we call the `textures' of spacetime. We point out the marked difference between the case when gravity is represented as a background spacetime versus the case when gravity acts like a thermodynamic bath to quantum particles. This points to the possibility of using gravitational decoherence measurements to discern whether gravity is intrinsically elemental or emergent.

C. Anastopoulos; B. L. Hu

2013-05-22T23:59:59.000Z

159

Quantum Weak Measurements and Cosmology  

E-Print Network (OSTI)

The indeterminism of quantum mechanics generally permits the independent specification of both an initial and a final condition on the state. Quantum pre-and-post-selection of states opens up a new, experimentally testable, sector of quantum mechanics, when combined with statistical averages of identical weak measurements. In this paper I apply the theory of weak quantum measurements combined with pre-and-post-selection to cosmology. Here, pre-selection means specifying the wave function of the universe or, in a popular semi-classical approximation, the initial quantum state of a subset of quantum fields propagating in a classical back-ground spacetime. The novel feature is post-selection: the additional specification of a condition on the quantum state in the far future. I discuss "natural" final conditions, and show how they may lead to potentially large and observable effects at the present cosmological epoch. I also discuss how pre-and-post-selected quantum contrast to the expectation value of the stress-energy-momentum tensor, resolving a vigorous debate from the 1970's. The paper thus provides a framework for computing large-scale cosmological effects arising from this new sector of quantum mechanics. A simple experimental test is proposed.

Paul Davies

2013-09-03T23:59:59.000Z

160

Modeling of the HERMES J105751.1+573027 submillimeter source lensed by a dark matter dominated foreground group of galaxies  

E-Print Network (OSTI)

We present the results of a gravitational lensing analysis of the bright $\\zs=2.957$ sub-millimeter galaxy (SMG), HERMES J105751.1+573027 found in {\\it Herschel}/SPIRE Science Demonstration Phase data from the Herschel Multi-tiered Extragalactic Survey (HerMES) project. The high resolution imaging available in optical and Near-IR channels, along with CO emission obtained with the Plateau de Bure Interferometer, allow us to precisely estimate the intrinsic source extension and hence estimate the total lensing magnification to be $\\mu=10.9\\pm 0.7$. We measure the half-light radius $R_{\\rm eff}$ of the source in the rest-frame Near-UV and $V$ bands that characterize the unobscured light coming from stars and find $R_{\\rm eff,*}= [2.0 \\pm 0.1]$ kpc, in good agreement with recent studies on the Submillimeter Galaxy population. This lens model is also used to estimate the size of the gas distribution ($R_{\\rm eff,gas}= [1.1\\pm0.5]$) kpc by mapping back in the source plane the CO (J=5-4) transition line emission. Th...

Gavazzi, R; Conley, A; Aguirre, J E; Amblard, A; Auld, R; Beelen, A; Blain, A; Blundell, R; Bock, J; Bradford, C M; Bridge, C; Brisbin, D; Burgarella, D; Chanial, P; Chapin, E; Christopher, N; Clements, D L; Cox, P; Djorgovski, S G; Dowell, C D; Eales, S; Earle, L; Ellsworth-Bowers, T P; Farrah, D; Franceschini, A; Fu, H; Glenn, J; Solares, E A González; Griffin, M; Gurwell, M A; Halpern, M; Ibar, E; Ivison, R J; Jarvis, M; Kamenetzky, J; Kim, S; Krips, M; Levenson, L; Lupu, R; Mahabal, A; Maloney, P D; Maraston, C; Marchetti, L; Marsden, G; Matsuhara, H; Mortier, A M J; Murphy, E; Naylor, B J; Neri, R; Nguyen, H T; Oliver, S J; Omont, A; Page, M J; Papageorgiou, A; Pearson, C P; Pérez-Fournon, I; Pohlen, M; Rangwala, N; Rawlings, J I; Raymond, G; Riechers, D; Rodighiero, G; Roseboom, I G; Rowan-Robinson, M; Schulz, B; Scott, Douglas; Scott, K S; Serra, P; Seymour, N; Shupe, D L; Smith, A J; Symeonidis, M; Tugwell, K E; Vaccari, M; Valiante, E; Valtchanov, I; Verma, A; Vieira, J D; Vigroux, L; Wang, L; Wardlow, J; Wiebe, D; Wright, G; Xu, C K; Zeimann, G; Zemcov, M; Zmuidzinas, J

2011-01-01T23:59:59.000Z

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161

Durability of Poly (Methyl Methacrylate) Lenses Used in Concentrating Photovoltaics (Presentation)  

DOE Green Energy (OSTI)

This presentation reports the findings of NREL's screen test to characterize the durability of poly (methyl methacrylate) lenses used in concentrated photovoltaics.

Miller, D.; Gedvilas, L.; To, B.; Kennedy, C.; Kurtz, S.

2010-10-21T23:59:59.000Z

162

The SDSS Discovery of a Strongly Lensed Post-Starburst Galaxy at z=0.766  

SciTech Connect

We present the first result of a survey for strong galaxy-galaxy lenses in Sloan Digital Sky Survey (SDSS) images. SDSS J082728.70+223256.4 was selected as a lensing candidate using selection criteria based on the color and positions of objects in the SDSS photometric catalog. Follow-up imaging and spectroscopy showed this object to be a lensing system. The lensing galaxy is an elliptical at z = 0.349 in a galaxy cluster. The lensed galaxy has the spectrum of a post-starburst galaxy at z = 0.766. The lensing galaxy has an estimated mass of {approx} 1.2 x 10{sup 12} M{sub {circle_dot}} and the corresponding mass to light ratio in the B-band is {approx} 26 M{sub {circle_dot}}/L{sub {circle_dot}} inside 1.1 effective radii of the lensing galaxy. Our study shows how catalogs drawn from multi-band surveys can be used to find strong galaxy-galaxy lenses having multiple lens images. Our strong lensing candidate selection based on photometry-only catalogs will be useful in future multi-band imaging surveys such as SNAP and LSST.

Shin, Min-Su; Strauss, Michael A.; Oguri, Masamune; Inada, Naohisa; Falco, Emilio E.; Broadhurst, Tom; Gunn, James E.

2008-09-30T23:59:59.000Z

163

Solid explosive plane-wave lenses pressed-to-shape with dies  

SciTech Connect

Solid-explosive plane-wave lenses 1", 2" and 4Ľ" in diameter have been mass-produced from components pressed-to-shape with aluminum dies. The method used to calculate the contour between the solid plane-wave lens components pressed-to-shape with the dies is explained. The steps taken to press, machine, and assemble the lenses are described. The method of testing the lenses, the results of those tests, and the corrections to the dies are reviewed. The work on the ˝", 8", and 12" diameter lenses is also discussed.

Olinger, B.

2007-11-01T23:59:59.000Z

164

Testing gravitational parity violation with coincident gravitational waves and short gamma-ray bursts  

E-Print Network (OSTI)

Gravitational parity violation is a possibility motivated by particle physics, string theory and loop quantum gravity. One effect of it is amplitude birefringence of gravitational waves, whereby left and right circularly-polarized waves propagate at the same speed but with different amplitude evolution. Here we propose a test of this effect through coincident observations of gravitational waves and short gamma-ray bursts from binary mergers involving neutron stars. Such gravitational waves are highly left or right circularly-polarized due to the geometry of the merger. Using localization information from the gamma-ray burst, ground-based gravitational wave detectors can measure the distance to the source with reasonable accuracy. An electromagnetic determination of the redshift from an afterglow or host galaxy yields an independent measure of this distance. Gravitational parity violation would manifest itself as a discrepancy between these two distance measurements. We exemplify such a test by considering one specific effective theory that leads to such gravitational parity-violation, Chern-Simons gravity. We show that the advanced LIGO-Virgo network and all-sky gamma-ray telescopes can be sensitive to the propagating sector of Chern-Simons gravitational parity violation to a level roughly two orders of magnitude better than current stationary constraints from the LAGEOS satellites.

Nicolas Yunes; Richard O'Shaughnessy; Benjamin J. Owen; Stephon Alexander

2010-05-18T23:59:59.000Z

165

Oceanic Internal Waves Are Not Weak Waves  

Science Conference Proceedings (OSTI)

It is shown that the oceanic internal wave field is too energetic by roughly two orders of magnitude to be treated theoretically as an assemblage of weakly interacting waves. This may be seen both from recent weak wave theoretical calculations ...

Greg Holloway

1980-06-01T23:59:59.000Z

166

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)

Mergers of two compact objects, like two neutron stars or a neutron star and a black hole, are the probable progenitor of short gamma-ray bursts. These events are also promising sources of gravitational waves, that are currently motivating related searches by an international network of gravitational wave detectors. Here we describe a search for gravitational waves from the in-spiral phase of two coalescing compact objects, in coincidence with short GRBs occurred during during LIGO's fifth science run and Virgo's first science run. The search includes 22 GRBs for which data from more than one of the detectors in the LIGO/Virgo network were available. No statistically significant gravitational-wave candidate has been found, and a parametric test shows no excess of weak gravitational-wave signals in our sample of GRBs. The 90\\%~C.L. median exclusion distance for GRBs in our sample is of 6.7 Mpc, under the hypothesis of a neutron star - black hole progenitor model.

Alexander Dietz

2010-06-17T23:59:59.000Z

167

Hydro-Gravitational-Dynamics of Planets and Dark Energy  

E-Print Network (OSTI)

Self-gravitational fluid mechanical methods termed hydro-gravitational-dynamics (HGD) predict plasma fragmentation 0.03 Myr after the turbulent big bang to form protosuperclustervoids, turbulent protosuperclusters, and protogalaxies at the 0.3 Myr transition from plasma to gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscous-inertial scales along turbulent vortex lines or in spirals, as observed. The plasma protogalaxies fragment on transition into white-hot planet-mass gas clouds (PFPs) in million-solar-mass clumps (PGCs) that become globular-star-clusters (GCs) from tidal forces or dark matter (PGCs) by freezing and diffusion into 0.3 Mpc halos with 97% of the galaxy mass. The weakly collisional non-baryonic dark matter diffuses to > Mpc scales and frag-ments to form galaxy cluster halos. Stars and larger planets form by binary mergers of the trillion PFPs per PGC on 0.03 Mpc galaxy accretion disks. Star deaths depend on rates of planet accretion and internal star mixing. Moderate accretion rates produce white dwarfs that evaporate surrounding gas planets by spin-radiation to form planetary nebulae before Supernova Ia events, dimming some events to give systematic distance errors misinterpreted as the dark energy hypothesis and overestimates of the universe age. Failures of standard LCDM cosmological models reflect not only obsolete Jeans 1902 fluid mechanical assumptions, but also failures of standard turbulence models that claim the cascade of turbulent kinetic energy is from large scales to small. Because turbulence is always driven at all scales by inertial-vortex forces the turbulence cascade is always from small scales to large.

Carl H. Gibson; Rudolph E. Schild

2008-08-24T23:59:59.000Z

168

Gravitational waves and gamma-ray bursts  

E-Print Network (OSTI)

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.

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

2012-04-18T23:59:59.000Z

169

The Fluid Mechanics of Gravitational Structure Formation  

E-Print Network (OSTI)

The standard model for gravitational structure formation in astrophysics, astronomy, and cosmology is questioned. Cold dark matter (CDM) hierarchical clustering cosmology neglects particle collisions, viscosity, turbulence and diffusion and makes predictions in conflict with observations. From Jeans 1902 and CDMHC, the non-baryonic dark matter NBDM forms small clumps during the plasma epoch after the big bang that ``cluster'' into larger clumps. CDM halo clusters collect the baryonic matter (H and He) by gravity so that after 300 Myr of ``dark ages'', huge, explosive (Population III) first stars appear, and then galaxies and galaxy clusters. Contrary to CDMHC cosmology, ``hydro-gravitational-dynamics'' HGD cosmology suggests the diffusive NBDM material cannot clump and the clumps cannot cluster. From HGD, the big bang results from an exothermic turbulent instability at Planck scales (10^{-35} m). Turbulent stresses cause an inflation of space and fossil density turbulence remnants that trigger gravitational i...

Gibson, C H

2006-01-01T23:59:59.000Z

170

Can dark energy be gravitational waves?  

E-Print Network (OSTI)

The idea that dark energy is gravitational waves may explain its strength and its time-evolution. A possible concept is that dark energy is the ensemble of coherent bursts (solitons) of gravitational waves originally produced when the first generation of super-massive black holes was formed. These solitons get their initial energy as well as keep up their energy density throughout the evolution of the universe by stimulating emission from a background, a process which we model by working out this energy transfer in a Boltzmann equation approach. New Planck data suggest that dark energy has increased in strength over cosmic time, supporting the concept here. The transit of these gravitational wave solitons may be detectable. Key tests include pulsar timing, clock jitter and the radio background.

Biermann, Peter L

2013-01-01T23:59:59.000Z

171

Fresnel lenses. (Latest citations from the US Patent Bibliographic file with exemplary claims). NewSearch  

SciTech Connect

The bibliography contains citations of selected patents concerning the design and implementation of Fresnel lenses. Citations focus on manufacturing methods and designs for specific applications. Fresnel lenses used in overhead projectors, solar concentrators, and infrared motion detectors are also described. (Contains a minimum of 71 citations and includes a subject term index and title list.)

Not Available

1994-10-01T23:59:59.000Z

172

Gravitational Field of a Spinning Cosmic String  

E-Print Network (OSTI)

We study the effect of internal space rotation on the gravitational properties of infinite straight and stationary cosmic string. From the approximate solution of Einsten equations for the spinning Q-lump string we obtain long range gravitational accelleration resembling that of a rotating massive cylindrical shell. We also compute the angular velocity of the inertial frame dragging and the angle of light deflection by the Q-lump string. Matter accretion on to spinning strings can play a role in galaxy formation when the angular velocity times the string width is comparable to the speed of light.

Eugen Simanek

2008-03-02T23:59:59.000Z

173

Light clocks in strong gravitational fields  

E-Print Network (OSTI)

We argue that the time measured by a light clock operating with photons rather than classical light requires a refinement of the standard clock postulate in general relativity. In the presence of a gravitational field, already the one-loop quantum corrections to classical Maxwell theory affect light propagation and the construction of observers' frames of reference. Carefully taking into account these kinematic effects, a concise geometric expression for the time shown by a light clock is obtained. This result has far-reaching implications for physics in strong gravitational fields.

Raffaele Punzi; Frederic P. Schuller; Mattias N. R. Wohlfarth

2009-02-11T23:59:59.000Z

174

Light clocks in strong gravitational fields  

E-Print Network (OSTI)

We argue that the time measured by a light clock operating with photons rather than classical light requires a refinement of the standard clock postulate in general relativity. In the presence of a gravitational field, already the one-loop quantum corrections to classical Maxwell theory affect light propagation and the construction of observers' frames of reference. Carefully taking into account these kinematic effects, a concise geometric expression for the time shown by a light clock is obtained. This result has far-reaching implications for physics in strong gravitational fields.

Punzi, Raffaele; Wohlfarth, Mattias N R

2009-01-01T23:59:59.000Z

175

An Einstein-like theory of gravity with a non-newtonian weak-field limit  

E-Print Network (OSTI)

We propose a model describing Einstein gravity coupled to a scalar field with an exponential potential. We show that the weak-field limit of the model has static solutions given by a gravitational potential behaving for large distances as \\ln r . The Newtonian term GM/r appears only as subleading. Our model can be used to give a phenomenological explanation of the rotation curves of the galaxies without postulating the presence of dark matter. This can be achieved only by giving up at galactic scales Einstein equivalence principle.

Mariano Cadoni

2003-12-09T23:59:59.000Z

176

On the history of fourth order metric theories of gravitation  

E-Print Network (OSTI)

We present the history of fourth order metric theories of gravitation from its beginning in 1918 until 1988.

R. Schimming; H. -J. Schmidt

2004-12-08T23:59:59.000Z

177

Numerical simulations of strong gravitational fields  

Science Conference Proceedings (OSTI)

Solutions to the Einstein equations of general relativity are constructed using numerical methods on high performance computing platforms. This article reviews the methods used to obtain numerical solutions to the Einstein equations and discusses some results from recent numerical simulations of highly nonlinear cosmological spacetimes as well as for time dependent black holes that emit gravitational waves.

David W. Hobill

1995-01-01T23:59:59.000Z

178

Nonperturbative unitarity of the gravitational Higgs mechanism  

SciTech Connect

In this paper, we discuss massive gravity in Minkowski space via the gravitational Higgs mechanism, which provides a nonperturbative definition thereof. Using this nonperturbative definition, we address the issue of unitarity by studying the full nonlinear Hamiltonian for the relevant metric degrees of freedom. While perturbatively unitarity is not evident, we argue that no negative norm state is present in the full nonlinear theory.

Iglesias, Alberto [Center for Cosmology and Particle Physics, New York University 4 Washington Place, New York, New York 10003 (United States); Kakushadze, Zurab [Quantigic registered Solutions LLC 200 Rector Place, 43C, New York, New York 10280 (United States)

2011-10-15T23:59:59.000Z

179

Parametric instability in scalar gravitational fields  

E-Print Network (OSTI)

We present a brief review on a new dynamical mechanism for a strong field effect in scalar tensor theory. Starting with a summary of the essential features of the theory and subsequent work by several authors, we analytically investigate the parametric excitation of a scalar gravitational field in a spherically symmetric radially pulsating neutron star.

T. B. Davies; C. H. -T. Wang; R. Bingham; J. T. Mendonca

2013-09-17T23:59:59.000Z

180

Spin effects in the weak interaction  

SciTech Connect

Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon.

Freedman, S.J. (Argonne National Lab., IL (USA) Chicago Univ., IL (USA). Dept. of Physics Chicago Univ., IL (USA). Enrico Fermi Inst.)

1990-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Weak measurements with a qubit meter  

E-Print Network (OSTI)

We derive schemes to measure the so-called weak values of quantum system observables by coupling of the system to a qubit meter system. We highlight, in particular, the meaning of the imaginary part of the weak values, and show how it can be measured directly on equal footing with the real part of the weak value. We present compact expressions for the weak value of single qubit observables and of product observables on qubit pairs. Experimental studies of the results are suggested with cold trapped ions.

Shengjun Wu; Klaus Mřlmer

2009-09-04T23:59:59.000Z

182

Gravitational field energy contribution to the neutron star mass  

E-Print Network (OSTI)

Neutron stars are discussed as laboratories of physics of strong gravitational fields. The mass of a neutron star is split into matter energy and gravitational field energy contributions. The energy of the gravitational field of neutron stars is calculated with three different approaches which give the same result. It is found that up to one half of the gravitational mass of maximum mass neutron stars is comprised by the gravitational field energy. Results are shown for a number of realistic equations of state of neutron star matter.

M. Dyrda; B. Kinasiewicz; M. Kutschera; A. Szmaglinski

2006-01-16T23:59:59.000Z

183

Gravitational-radiation losses from the pulsar-white-dwarf binary PSR J1141-6545  

E-Print Network (OSTI)

Pulsars in close binary orbit around another neutron star or a massive white dwarf make ideal laboratories for testing the predictions of gravitational radiation and self-gravitational effects. We report new timing measurements of the pulsar-white-dwarf binary PSR J1141-6545, providing strong evidence that such asymmetric systems have gravitational wave losses that are consistent with general relativity. The orbit is found to be decaying at a rate of $1.04\\pm0.06$ times the general relativistic prediction and the Shapiro delay is consistent with the orbital inclination angle derived from scintillation measurements. The system provides a unique test-bed for tensor-scalar theories of gravity; our current measurements place stringent constraints in the theory space, with a limit of $\\alpha_0^2 < 2.1 \\times 10^{-5}$ for weakly non-linear coupling and an asymptotic limit of $\\alpha_0^2 < 3.4 \\times 10^{-6}$ for strongly non-linear coupling, where $\\alpha_0$ is the linear coupling strength of matter to an underlying scalar field. This asymptotic limit is nearly three times smaller than the Cassini bound ($\\alpha_0^2 \\approx 10^{-5}$).

N. D. Ramesh Bhat; Matthew Bailes; Joris P. W. Verbiest

2008-04-07T23:59:59.000Z

184

THE IMPACT OF THERMODYNAMICS ON GRAVITATIONAL COLLAPSE: FILAMENT FORMATION AND MAGNETIC FIELD AMPLIFICATION  

Science Conference Proceedings (OSTI)

Stars form by the gravitational collapse of interstellar gas. The thermodynamic response of the gas can be characterized by an effective equation of state. It determines how gas heats up or cools as it gets compressed, and hence plays a key role in regulating the process of stellar birth on virtually all scales, ranging from individual star clusters up to the galaxy as a whole. We present a systematic study of the impact of thermodynamics on gravitational collapse in the context of high-redshift star formation, but argue that our findings are also relevant for present-day star formation in molecular clouds. We consider a polytropic equation of state, P = k{rho}{sup {Gamma}}, with both sub-isothermal exponents {Gamma} 1. We find significant differences between these two cases. For {Gamma} > 1, pressure gradients slow down the contraction and lead to the formation of a virialized, turbulent core. Weak magnetic fields are strongly tangled and efficiently amplified via the small-scale turbulent dynamo on timescales corresponding to the eddy-turnover time at the viscous scale. For {Gamma} < 1, on the other hand, pressure support is not sufficient for the formation of such a core. Gravitational contraction proceeds much more rapidly and the flow develops very strong shocks, creating a network of intersecting sheets and extended filaments. The resulting magnetic field lines are very coherent and exhibit a considerable degree of order. Nevertheless, even under these conditions we still find exponential growth of the magnetic energy density in the kinematic regime.

Peters, Thomas; Klessen, Ralf S.; Federrath, Christoph; Smith, Rowan J. [Zentrum fuer Astronomie, Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Schleicher, Dominik R. G. [Institut fuer Astrophysik, Georg-August-Universitaet, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Banerjee, Robi [Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany); Sur, Sharanya, E-mail: tpeters@physik.uzh.ch [Raman Research Institute, C. V. Raman Avenue, Sadashivnagar, Bangalore 560080 (India)

2012-12-01T23:59:59.000Z

185

CP Violation, Neutral Currents, and Weak Equivalence  

DOE R&D Accomplishments (OSTI)

Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

Fitch, V. L.

1972-03-23T23:59:59.000Z

186

Observing Lense-Thirring Precession in Tidal Disruption Flares  

E-Print Network (OSTI)

When a star is tidally disrupted by a supermassive black hole (SMBH), the streams of liberated gas form an accretion disk after their return to pericenter. We demonstrate that Lense-Thirring precession in the spacetime around a rotating SMBH can produce significant time evolution of the disk angular momentum vector, due to both the periodic precession of the disk and the nonperiodic, differential precession of the bound debris streams. Jet precession and periodic modulation of disk luminosity are possible consequences. The persistence of the jetted X-ray emission in the Swift J164449.3+573451 flare suggests that the jet axis was aligned with the spin axis of the SMBH during this event.

Nicholas Stone; Abraham Loeb

2011-09-29T23:59:59.000Z

187

On the Structure of Weakly Acyclic Games  

E-Print Network (OSTI)

The class of weakly acyclic games, which includes potential games and dominance-solvable games, captures many practical application domains. In a weakly acyclic game, from any starting state, there is a sequence of better-response moves that leads to a pure Nash equilibrium; informally, these are games in which natural distributed dynamics, such as better-response dynamics, cannot enter inescapable oscillations. We establish a novel link between such games and the existence of pure Nash equilibria in subgames. Specifically, we show that the existence of a unique pure Nash equilibrium in every subgame implies the weak acyclicity of a game. In contrast, the possible existence of multiple pure Nash equilibria in every subgame is insufficient for weak acyclicity in general; here, we also systematically identify the special cases (in terms of the number of players and strategies) for which this is sufficient to guarantee weak acyclicity.

Fabrikant, Alex; Schapira, Michael

2011-01-01T23:59:59.000Z

188

Gravitational Wave Sources from New Physics  

E-Print Network (OSTI)

Forthcoming advances in direct gravitational wave detection from kilohertz to nanohertz frequencies have unique capabilities to detect signatures from or set meaningful constraints on a wide range of new cosmological phenomena and new fundamental physics. A brief survey is presented of the post-inflationary gravitational radiation backgrounds predicted in cosmologies that include intense new classical sources such as first-order phase transitions, late-ending inflation, and dynamically active mesoscopic extra dimensions. LISA will provide the most sensitive direct probes of such phenomena near TeV energies or Terascale. LISA will also deeply probe the broadband background, and possibly bursts, from loops of cosmic superstrings predicted to form in current models of brane inflation.

Craig J. Hogan

2006-08-25T23:59:59.000Z

189

The New Science of Gravitational Waves  

E-Print Network (OSTI)

A brief survey is presented of new science that will emerge during the decades ahead from direct detection of gravitational radiation. Interferometers on earth and in space will probe the universe in an entirely new way by directly sensing motions of distant matter over a range of more than a million in frequency. The most powerful sources of gravitational (or indeed any form of) energy in the universe are inspiralling and merging binary black holes; with LISA data, they will become the most distant, most completely and precisely modeled, and most accurately measured systems in astronomy outside the solar system. Other sources range from already known and named nearby Galactic binary stars, to compact objects being swallowed by massive black holes, to possible effects of new physics: phase transitions and superstrings from the early universe, or holographic noise from quantum fluctuations of local spacetime.

Craig J. Hogan

2007-09-05T23:59:59.000Z

190

The New Science of Gravitational Waves  

E-Print Network (OSTI)

A brief survey is presented of new science that will emerge during the decades ahead from direct detection of gravitational radiation. Interferometers on earth and in space will probe the universe in an entirely new way by directly sensing motions of distant matter over a range of more than a million in frequency. The most powerful sources of gravitational (or indeed any form of) energy in the universe are inspiralling and merging binary black holes; with LISA data, they will become the most distant, most completely and precisely modeled, and most accurately measured systems in astronomy outside the solar system. Other sources range from already known and named nearby Galactic binary stars, to compact objects being swallowed by massive black holes, to possible effects of new physics: phase transitions and superstrings from the early universe, or holographic noise from quantum fluctuations of local spacetime.

Hogan, Craig J

2007-01-01T23:59:59.000Z

191

Interferometer Techniques for Gravitational-Wave Detection  

E-Print Network (OSTI)

Several km-scale gravitational-wave detectors have been constructed world wide. These instruments combine a number of advanced technologies to push the limits of precision length measurement. The core devices are laser interferometers of a new kind; developed from the classical Michelson topology these interferometers integrate additional optical elements, which significantly change the properties of the optical system. Much of the design and analysis of these laser interferometers can be performed using well-known classical optical techniques, however, the complex optical layouts provide a new challenge. In this review we give a textbook-style introduction to the optical science required for the understanding of modern gravitational wave detectors, as well as other high-precision laser interferometers. In addition, we provide a number of examples for a freely available interferometer simulation software and encourage the reader to use these examples to gain hands-on experience with the discussed optical methods.

Andreas Freise; Kenneth Strain

2009-09-21T23:59:59.000Z

192

On the running of the gravitational constant  

E-Print Network (OSTI)

We show that there is no useful and universal definition of a running gravitational constant, G(E), in the perturbative regime below the Planck scale. By consideration of the loop corrections to several physical processes, we show that the quantum corrections vary greatly, in both magnitude and sign, and do not exhibit the required properties of a running coupling constant. We comment on the potential challenges of these results for the Asymptotic Safety program.

Mohamed M. Anber; John F. Donoghue

2011-11-11T23:59:59.000Z

193

On the running of the gravitational constant  

E-Print Network (OSTI)

We show that there is no useful and universal definition of a running gravitational constant, G(E), in the perturbative regime below the Planck scale. By consideration of the loop corrections to several physical processes, we show that the quantum corrections vary greatly, in both magnitude and sign, and do not exhibit the required properties of a running coupling constant. We comment on the potential challenges of these results for the Asymptotic Safety program.

Anber, Mohamed M

2011-01-01T23:59:59.000Z

194

Time delay for the gravitational lens system B0218+357  

E-Print Network (OSTI)

Measurement of the time delay between multiple images of a gravitational lens system is potentially an accurate method of determining the Hubble constant over cosmological distances. One of the most promising candidates for an application of this technique is the system B0218+357 which was found in the Jodrell Bank/VLA Astrometric Survey (JVAS). This system consists of two images of a compact radio source, separated by 335 milliarcsec, and an Einstein ring which can provide a strong constraint on the mass distribution in the lens. We present here the results of a three-month VLA monitoring campaign at two frequencies. The data are of high quality and both images show clear variations in total flux density, percentage polarization and polarization position angle at both frequencies. The time delay between the variations in the two images has been calculated using a chi-squared minimization to be 10.5+/-0.4 days at 95 per cent confidence, with the error being derived from Monte-Carlo simulations of the light curves. Although mass modelling of the system is at a preliminary stage, taking the lensing galaxy to be a singular isothermal ellipsoid and using the new value for the time delay gives a value for the Hubble constant of 69+13/-19 km/s/Mpc, again at 95 per cent confidence.

A. D. Biggs; I. W. A. Browne; P. Helbig; L. V. E. Koopmans; P. N. Wilkinson; R. A. Perley

1998-11-18T23:59:59.000Z

195

Evidence for Hydro-Gravitational Structure Formation Theory versus Cold-Dark-Matter, Hierarchical-Clustering, and Jeans 1902  

E-Print Network (OSTI)

Observations are compared to conflicting predictions about self-gravitational structure formation by the hydro-gravitational theory (HGT) of Gibson 1996-2003 versus cold-dark-matter hierarchical-clustering-cosmology (CDMHCC) and the Jeans 1902 criterion. According to HGT, gravitational structures form immediately after mass-energy equality by plasma fragmentation at 30,000 years when viscous and weak turbulence forces first balance gravitational forces within the horizon L_H = ct < L_J = c/[3\\rho G]^1/2, contrary to the Jeans 1902 criterion. Buoyancy forces fossilize the 10^-12 s^-1 rate-of-strain and the 10^-17 kg m^-3 baryonic density. The non-baryonic dark matter (NBDM) diffuses into the voids rather than forming cold-dark-matter (CDM) halos required by CDMHCC. From HGT, supercluster-mass to galaxy-mass fragments exist at the plasma to gas transition, and these fragment further to form proto-globular-star clusters (PGCs) and planetary-mass primordial-fog-particles (PFPs): the baryonic dark matter of the interstellar-medium and inner-galaxy-dark-matter-halos, from which all planets and stars are formed by accretion (Gibson 1996, Schild 1996). From HGT and a rich cluster mass profile (Tyson and Fischer 1995), D_NBDM = 6 x10^28 m^2 s^-1, m_NBDM <= 10^-33 kg, and the NBDM forms outer-galaxy halos after 300,000 years.

Carl H. Gibson; Rudy Schild

2003-04-27T23:59:59.000Z

196

 

NLE Websites -- All DOE Office Websites (Extended Search)

Galaxies, Clusters, and Cosmology with Weak Lensing Magnification Galaxies, Clusters, and Cosmology with Weak Lensing Magnification Hendrik Hildebrandt University of British Columbia Abstract: Weak gravitational lensing is one of the major methods to study the dark sector of the Universe on a large variety of mass- and length-scales. So far most observations employed the shear effect of weak lensing. Recently, it has been shown that also the magnification effect can be turned into a powerful, complimentary tool. In this talk I will review the theory behind magnification measurements and highlight advantages and weaknesses of this approach in comparison to shear-based measurements. Furthermore, I will present observations of weak lensing magnification induced by galaxies and galaxy clusters and explain how those will help us to answer open questions

197

Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Technology (Revised) (Presentation)  

DOE Green Energy (OSTI)

Concentrating photovoltaic (CPV) technology recently gained interest based on its expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems employ Fresnel lenses composed of poly(methyl methacrylate) (PMMA) to obtain a high optical flux density on the cell. The optical and mechanical durability of these lenses, however, is not well established relative to the desired surface life of 30 years. Our research aims to quantify the expected lifetime of PMMA in key market locations (FL, AZ, and CO).

Miller, D. C.; Carloni, J. D.; Pankow, J. W.; Gjersing, E. L.; To, B.; Packard, C. E.; Kennedy, C. E.; Kurtz, S. R.

2012-01-01T23:59:59.000Z

198

Two-dimensional kinematics of SLACS lenses: I. Phase-space analysis of the early-type galaxy SDSS J2321-097 at z=0.1  

E-Print Network (OSTI)

We present the first results of a combined VLT VIMOS integral-field unit and Hubble Space Telescope (HST)/ACS study of the early-type lens galaxy SDSS J2321-097 at z=0.0819, extending kinematic studies to a look-back time of 1 Gyr. This system, discovered in the Sloan Lens ACS Survey (SLACS), has been observed as part of a VLT Large Programme with the goal of obtaining two-dimensional stellar kinematics of 17 early-type galaxies to z~0.35 and Keck spectroscopy of an additional dozen lens systems. Bayesian modelling of both the surface brightness distribution of the lensed source and the two-dimensional measurements of velocity and velocity dispersion has allowed us, under the only assumptions of axisymmetry and a two-integral stellar distribution function (DF) for the lens galaxy, to dissect this galaxy in three dimensions and break the classical mass--anisotropy, mass-sheet and inclination--oblateness degeneracies. Our main results are that the galaxy (i) has a total density profile well described by a single power-law rho propto r^{-gamma'} with gamma'=2.06^{+0.03}_{-0.06}; (ii) is a very slow rotator (specific stellar angular momentum parameter lambda_R = 0.075); (iii) shows only mild anisotropy (delta ~ 0.15); and (iv) has a dark matter contribution of ~30 per cent inside the effective radius. Our first results from this large combined imaging and spectroscopic effort with the VLT, Keck and HST show that the structure of massive early-type galaxies beyond the local Universe can now be studied in great detail using the combination of stellar kinematics and gravitational lensing. Extending these studies to look-back times where evolutionary effects become measurable holds great promise for the understanding of formation and evolution of early-type galaxies.

Oliver Czoske; Matteo Barnabe; Leon V. E. Koopmans; Tommaso Treu; Adam S. Bolton

2007-11-06T23:59:59.000Z

199

Gravitational Energy-Momentum Density in Teleparallel Gravity  

E-Print Network (OSTI)

In the context of a gauge theory for the translation group, a conserved energy-momentum gauge current for the gravitational field is obtained. It is a true spacetime and gauge tensor, and transforms covariantly under global Lorentz transformations. By rewriting the gauge gravitational field equation in a purely spacetime form, it becomes the teleparallel equivalent of Einstein's equation, and the gauge current reduces to the M{\\o}ller's canonical energy-momentum density of the gravitational field.

V. C. de Andrade; L. C. T. Guillen; J. G. Pereira

2000-03-27T23:59:59.000Z

200

Gravimagnetic shock waves and gravitational-wave experiments  

E-Print Network (OSTI)

Causes of the unsatisfactory condition of the gravitational-wave experiments are discussed and a new outlook at the detection of gravitational waves of astrophysical origin is proposed. It is shown that there are strong grounds for identifying the so-called giant pulses in the pulsar NP 0532 radiation with gravimagnetic shock waves (GMSW) excited in the neutron star magnetosphere by sporadic gravitational radiation of this pulsar.

Yu. G. Ignatyev

2011-01-09T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

The gravitation energy for a cylindrically and spherically symmetrical system  

E-Print Network (OSTI)

It has been shown that t00 component of the energy-momentum pseudotensor in the case of cylindrically symmetrical static gravitational field cannot be interpreted as energy density of the gravitation field. An approach has been suggested allows one to express the energy density of the cylindrically or spherically symmetrical static gravitation field in terms of the metric tensor components. The approach based on the consideration of the process of isothermal compression of a cylinder consisted of incoherent matter.

Roald Sosnovskiy

2005-07-04T23:59:59.000Z

202

The gravitational field energy density for symmetrical and asymmetrical systems  

E-Print Network (OSTI)

The relativistic theory of gravitation has the considerable difficulties by description of the gravitational field energy. Pseudotensor t00 in the some cases cannot be interpreted as energy density of the gravitational field. In [1] the approach was proposed, which allow to express the energy density of such a field through the components of a metric tensor. This approach based on the consideration of the isothermal compression of the layer consisted of the incoherent matter. It was employ to the cylindrically and spherically symmetrical static gravitational field. In presented paper the approach is developed.

Roald Sosnovskiy

2006-07-25T23:59:59.000Z

203

The earth's absolute gravitation potential function in the prospect 'gravitational potential metering' of geological objects and earthquake centers  

E-Print Network (OSTI)

The direct problem of the detection of the Earth's absolute gravitation potential maximum value (MGP) was solved. The inverse problem finding of the Earth maximum gravitation (where there is a maximum of gravitation field intensity and a potential function has a 'bending point') with the help of MGP was solved as well. The obtained results show that the revealed Earth maximum gravitation coincides quite strictly with the cseismic D" layer on the border of the inner and outer (liquid) core. The validity of the method of an absolute gravitation potential detection by the equal- potential velocity was proved as 'gravitation potential measurement' or 'Vs-gravity method'. The prospects of this method for detecting of low-power or distant geological objects with abnormal density and the possible earthquakes with low density was shown.

Aleksandr Fridrikson; Marina Kasatochkina

2009-04-08T23:59:59.000Z

204

Gravitational Instability in Radiation Pressure Dominated Backgrounds  

E-Print Network (OSTI)

I consider the physics of gravitational instabilities in the presence of dynamically important radiation pressure and gray radiative diffusion, governed by a constant opacity, kappa. For any non-zero radiation diffusion rate on an optically-thick scale, the medium is unstable unless the classical gas-only isothermal Jeans criterion is satisfied. When diffusion is "slow," although the dynamical Jeans instability is stabilized by radiation pressure on scales smaller than the adiabatic Jeans length, on these same spatial scales the medium is unstable to a diffusive mode. In this regime, neglecting gas pressure, the characteristic timescale for growth is independent of spatial scale and given by (3 kappa c_s^2)/(4 pi G c), where c_s is the adiabatic sound speed. This timescale is that required for a fluid parcel to radiate away its thermal energy content at the Eddington limit, the Kelvin-Helmholz timescale for a radiation pressure supported self-gravitating object. In the limit of "rapid" diffusion, radiation does nothing to suppress the Jeans instability and the medium is dynamically unstable unless the gas-only Jeans criterion is satisfied. I connect with treatments of Silk damping in the early universe. I discuss several applications, including photons diffusing in regions of extreme star formation (starburst galaxies & pc-scale AGN disks), and the diffusion of cosmic rays in normal galaxies and galaxy clusters. The former (particularly, starbursts) are "rapidly" diffusing and thus cannot be supported against dynamical instability in the linear regime by radiation pressure alone. The latter are more nearly "slowly" diffusing. I speculate that the turbulence in starbursts may be driven by the dynamical coupling between the radiation field and the self-gravitating gas, perhaps mediated by magnetic fields. (Abridged)

Todd A. Thompson

2008-04-21T23:59:59.000Z

205

The Fluid Mechanics of Gravitational Structure Formation  

E-Print Network (OSTI)

The standard model for gravitational structure formation in astrophysics, astronomy, and cosmology is questioned. Cold dark matter (CDM) hierarchical clustering cosmology neglects particle collisions, viscosity, turbulence and diffusion and makes predictions in conflict with observations. From Jeans 1902 and CDMHC, the non-baryonic dark matter NBDM forms small clumps during the plasma epoch after the big bang that ``cluster'' into larger clumps. CDM halo clusters collect the baryonic matter (H and He) by gravity so that after 300 Myr of ``dark ages'', huge, explosive (Population III) first stars appear, and then galaxies and galaxy clusters. Contrary to CDMHC cosmology, ``hydro-gravitational-dynamics'' HGD cosmology suggests the diffusive NBDM material cannot clump and the clumps cannot cluster. From HGD, the big bang results from an exothermic turbulent instability at Planck scales (10^{-35} m). Turbulent stresses cause an inflation of space and fossil density turbulence remnants that trigger gravitational instability at protosupercluster masses (10^{46} kg) in the H-He plasma. These fragment along plasma turbulence vortex lines to form protogalaxy masses (10^{42} kg) just before the transition to gas. The gas has x10^{-13} smaller viscosity, so it fragments at planetary and globular-star-cluster masses (10^{25} and 10^{36} kg) to form the baryonic dark matter (BDM). Observations from the Hubble Space Telescope show protogalaxies (PGs) in linear clusters reflecting their likely fragmentation on plasma vortex lines. From merging BDM planets, these PGs gently form small stars in globular clusters <1 Myr after the big bang without the dark ages, superstars, or reionization of CDM cosmology.

Carl H. Gibson

2006-10-20T23:59:59.000Z

206

Standing gravitational waves from domain walls  

SciTech Connect

We construct a plane symmetric, standing gravitational wave for a domain wall plus a massless scalar field. The scalar field can be associated with a fluid which has the properties of 'stiff' matter, i.e., matter in which the speed of sound equals the speed of light. Although domain walls are observationally ruled out in the present era, the solution has interesting features which might shed light on the character of exact nonlinear wave solutions to Einstein's equations. Additionally this solution may act as a template for higher dimensional 'brane-world' model standing waves.

Gogberashvili, Merab [Andronikashvili Institute of Physics, 6 Tamarashvili Street, Tbilisi 0177 (Georgia); Javakhishvili Tbilisi State University, 3 Chavchavadze Avenue, Tbilisi 0128 (Georgia); California State University, Fresno, Physics Department, Fresno, California 93740-8031 (United States); Myrzakul, Shynaray [Department of General and Theoretical Physics, Gumilev Eurasian National University, Astana, 010008 (Kazakhstan); California State University, Fresno, Physics Department, Fresno, California 93740-8031 (United States); Singleton, Douglas [California State University, Fresno, Physics Department, Fresno, California 93740-8031 (United States); Institute of Gravitation and Cosmology, Peoples' Friendship University of Russia, Moscow 117198 (Russian Federation)

2009-07-15T23:59:59.000Z

207

The road to gravitational-wave astronomy  

E-Print Network (OSTI)

Gravitational-wave astronomy is an area of great promise, yet to be realized. While we are waiting for the first (undisputed!) direct detection of these elusive waves it is useful to take stock and consider the challenges that need to be met if we want this field to reach its full potential. This write-up provides a brief introduction to some of the key ideas and the current state-of-play, and lists a range of modelling questions that need to be considered in the future.

Andersson, N

2010-01-01T23:59:59.000Z

208

Spherical gravitating condensers in general relativity  

Science Conference Proceedings (OSTI)

By a spherical gravitating condenser we mean two concentric charged shells made of perfect fluids restricted by the condition that the electric field is nonvanishing only between the shells. Flat space is assumed inside the inner shell. By using Israel's formalism we first analyze the general system of N shells and then concentrate on the two-shell condensers. Energy conditions are taken into account; physically interesting cases are summarized in two tables, but also more exotic situations in which, for example, the inner shell may occur below the inner horizon of the corresponding Reissner-Nordstroem geometry or the spacetime is curved only inside the condenser are considered. Classical limits are mentioned.

Bicak, J.; Guerlebeck, N. [Institute of Theoretical Physics, Charles University, V Holesovickach 2, 180 00 Praha 8-Holesovice (Czech Republic); Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Am Muehlenberg 1, D-14476 Golm (Germany)

2010-05-15T23:59:59.000Z

209

Does gravitational collapse lead to singularities?  

E-Print Network (OSTI)

According to conventional modelling by general relativity the collapse of radially symmetric gravitating objects may end in a singular state. But by inclusion of potential energy into the energy tensor, which is required to guarantee global energy conservation, the occurrence of singularities is avoided. Instead the final states of the collapse of mass concentrations of arbitrary size are nuclear matter objects, from which jets of matter can be recycled into space. The mysterious dark energy, supposed as the main constituent of the universe, may even be the potential energy of matter itself.

Ernst Fischer

2013-03-23T23:59:59.000Z

210

A high-frequency gravitational-wave burst search with LIGO's Hanford site  

E-Print Network (OSTI)

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a network of long-arm interferometers designed to directly measure gravitational-wave strain. Direct observation of gravitational waves would provide a test ...

Villadsen, Jacqueline Rose

2009-01-01T23:59:59.000Z

211

A high-frequency gravitational-wave burst search with LIGO's Hanford site.  

E-Print Network (OSTI)

??The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a network of long-arm interferometers designed to directly measure gravitational-wave strain. Direct observation of gravitational waves would provide… (more)

Villadsen, Jacqueline Rose

2009-01-01T23:59:59.000Z

212

Heat and Gravitation. I. The Action Principle  

E-Print Network (OSTI)

This first article of a series formulates the thermodynamics of ideal gases in a constant gravitational field in terms of an action principle that is closely integrated with thermodynamics. The theory, in its simplest form, does not deviate from standard practice, but it lays the foundations for a more systematic approach to the various extensions, such as the incorporation of radiation, the consideration of mixtures and the integration with General Relativity. We study the interaction between an ideal gas and the photon gas, and propose a new approach to this problem. We study the propagation of sound in a vertical, isothermal column and are led to suggest that the theory is incomplete, and to ask whether the true equilibrium state of an ideal gas may turn out be adiabatic, in which case the role of solar radiation is merely to compensate for the loss of energy by radiation into the cosmos. An experiment with a centrifuge is proposed, to determine the influence of gravitation on the equilibrium distribution with a very high degree of precision.

Christian Fronsdal

2008-12-30T23:59:59.000Z

213

Charge-Confining Gravitational Electrovacuum Shock Wave  

E-Print Network (OSTI)

In previous publications we have extensively studied spherically symmetric solutions of gravity coupled to a non-standard type of non-linear electrodynamics containing a square root of the ordinary Maxwell Lagrangian (the latter is known to yield QCD-like confinement in flat space-time). A class of these solutions describe non-standard black holes of Reissner-Nordstroem-(anti-)-de-Sitter type with an additional constant radial vacuum electric field, in particular, a non-asymptotically flat Reissner-Nordstroem-type black hole. Here we study the ultra-relativistic boost (Aichelburg-Sexl-type) limit of the latter and show that, unlike the ordinary Reissner-Nordstroem case, we obtain a gravitational electrovacuum shock wave as a result of the persistence of the gauge field due to the "square-root" Maxwell Lagrangian term. Next, we show that this gravitational electrovacuum shock wave confines charged test particles (both massive and massless) within a finite distance from its front.

Eduardo Guendelman; Emil Nissimov; Svetlana Pacheva

2013-10-06T23:59:59.000Z

214

AGAPE Andromeda Gravitational Amplification Pixel Experiment  

E-Print Network (OSTI)

The aim of the AGAPE (Andromeda Gravitational Amplification Pixel Experiment), experiment which has been first proposed in June 1992 is to examine the distribution of massive astrophysical compact halo objects ((MACHO's) which possibly are in the galactic haloes and which could account for the missing dark matter. Those objects have a mass which is a fraction of solar mass and could be detected by gravitational microlensing: the light of a star is amplified when a MACHO is crossing its line of sight from the earth. This technique has been proposed by Paczy\\'nski in 1986. The AGAPE collaboration applies this technique in an original way by using, as target stars, the stars of another galaxy without resolving them. The recent progresses in photometry with CCD allow now to see tiny variations of the surface brightness of a galaxy like M~31. Those tiny variations can be the result of a single microlensing event on the background stars contributing to the surface brightness. The AGAPE collaboration has now cumulat...

Ansari, R; Baillon, Paul; Bouquet, A; Coupinot, G; Coutures, C; Ghesquičre, C; Giraud-Héraud, Yannick; Gondolo, P; Hecquet, J; Kaplan, J; Le Du, Y; Melchior, A L; Moniez, M; Picat, J P; Soucail, G

1999-01-01T23:59:59.000Z

215

Heat and Gravitation. I. The Action Principle  

E-Print Network (OSTI)

In this first article of a series we formulate the thermodynamics of ideal gases in a constant gravitational field in terms of an action principle. The theory, in its simplest form, does not differ from standard practice, but it lays the foundations for a more systematic approach to the various extensions, such as the incorporation of radiation, the consideration of mixtures and the incorporation of General Relativty. An important conclusion is that a dynamical theory that incorporates the isothermal equilibrium of an ideal gas in a gravitational field does not seem to exist. The true equilibrium state of an ideal gas may in fact be adiabatic, in which case the role of solar radiation is merely to compensate for the loss of energy due to black body radiation into the cosmos. We study the interaction between an ideal gas and the photon gas, and propose a new approach to this problem. An experiment that involves a centrifuge and that has wider implications in view of the equivalence principle is proposed, to de...

Fronsdal, Christian

2008-01-01T23:59:59.000Z

216

Shock Waves in Weakly Compressed Granular Media  

E-Print Network (OSTI)

We experimentally probe nonlinear wave propagation in weakly compressed granular media, and observe a crossover from quasi-linear sound waves at low impact, to shock waves at high impact. We show that this crossover grows with the confining pressure $P_0$, whereas the shock wave speed is independent of $P_0$ --- two hallmarks of granular shocks predicted recently. The shocks exhibit powerlaw attenuation, which we model with a logarithmic law implying that local dissipation is weak. We show that elastic and potential energy balance in the leading part of the shocks.

Siet van den Wildenberg; Rogier van Loo; Martin van Hecke

2013-04-23T23:59:59.000Z

217

Hall Magnetohydrodynamics of weakly-ionized plasma  

E-Print Network (OSTI)

We show that the Hall scale in a weakly ionized plasma depends on the fractional ionization of the medium and, Hall MHD description becomes important whenever the ion-neutral collision frequency is comparable to the ion-gyration frequency, or, the ion-neutral collisional mean free path is smaller than the ion gyro-radius. Wave properties of a weakly-ionized plasma also depends on the fractional ionization and plasma Hall parameters, and whistler mode is the most dominant mode in such a medium. Thus Hall MHD description will be important in astrophysical disks, dark molecular clouds, neutron star crusts, and, solar and planetary atmosphere.

B. P. Pandey; Mark Wardle

2006-08-01T23:59:59.000Z

218

Weak Solutions for Dislocation Type Equations  

E-Print Network (OSTI)

We describe recent results obtained by G. Barles, P. Cardaliaguet, R. Monneau and the author recently. They are concerned with nonlocal Eikonal equations arising in the study of the dynamics of dislocation lines in crystals. These equations are nonlocal but also non monotone. We use a notion of weak solution to provide solutions for all time. Then, we discuss the link between these weak solutions and the classical viscosity solutions, and state some uniqueness results in particular cases. A counter-example to uniqueness is given.

Ley, Olivier

2008-01-01T23:59:59.000Z

219

Conservation laws in gravitational theories with general nonminimal coupling  

E-Print Network (OSTI)

We use the Lagrange-Noether methods to derive the conservation laws for models in which matter interacts nonminimally with the gravitational field. The nonminimal coupling function can depend arbitrarily on the gravitational field strength. The obtained result generalizes earlier findings. The generalized conservation laws provide the basis for the derivation of the equations of motion for the nonminimally coupled test bodies.

Yuri N. Obukhov; Dirk Puetzfeld

2013-03-25T23:59:59.000Z

220

M31 PIXEL LENSING EVENT OAB-N2: A STUDY OF THE LENS PROPER MOTION  

Science Conference Proceedings (OSTI)

We present an updated analysis of the M31 pixel lensing candidate event OAB-N2 previously reported by Calchi Novati et al. Here we take advantage of new data both astrometrical and photometrical. For astrometry: using archival 4 m KPNO and Hubble Space Telescope/WFPC2 data we perform a detailed analysis of the event source whose result, although not fully conclusive on the source magnitude determination, is confirmed by the following light curve photometry analysis. For photometry: first, unpublished WeCAPP data allow us to confirm OAB-N2, previously reported only as a viable candidate, as a well-constrained pixel lensing event. Second, this photometry enables a detailed analysis in the event parameter space including the effects due to a finite source size. The combined results of these analyses allow us to put a strong lower limit on the lens proper motion. This outcome favors the MACHO lensing hypothesis over self-lensing for this individual event and points the way toward distinguishing between the MACHO and self-lensing hypotheses from larger data sets.

Calchi Novati, S.; Bozza, V.; Mancini, L.; Scarpetta, G. [Dipartimento di Fisica 'E. R. Caianiello', Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano (Italy); Dall'Ora, M. [INAF-OAC, Naples (Italy); Gould, A. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Bruni, I.; Gualandi, R. [INAF-OAB, Bologna (Italy); De Paolis, F.; Ingrosso, G.; Strafella, F. [Dipartimento di Fisica, Universita del Salento, Via Arnesano, 73100 Lecce (Italy); Dominik, M. [SUPA, University of St. Andrews, School of Physics and Astronomy, North Haugh, St. Andrews, KY16 9SS (United Kingdom); Jetzer, Ph. [Institute for Theoretical Physics, University of Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Nucita, A. [XMM-Newton Science Operations Centre, ESAC, ESA, P.O. Box 78, 28691 Villanueva de la Canada, Madrid (Spain); Sereno, M. [Dipartimento di Fisica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

2010-07-10T23:59:59.000Z

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221

Dark matter, dark energy and gravitational proprieties of antimatter  

E-Print Network (OSTI)

We suggest that the eventual gravitational repulsion between matter and antimatter may be a key for understanding of the nature of dark matter and dark energy. If there is gravitational repulsion, virtual particle-antiparticle pairs in the vacuum, may be considered as gravitational dipoles. We use a simple toy model to reveal a first indication that the gravitational polarization of such a vacuum, caused by baryonic matter in a Galaxy, may produce the same effect as supposed existence of dark matter. In addition, we argue that cancellation of gravitational charges in virtual particle-antiparticle pairs, may be a basis for a solution of the cosmological constant problem and identification of dark energy with vacuum energy. Hence, it may be that dark matter and dark energy are not new, unknown forms of matter-energy but an effect of complex interaction between quantum vacuum and known baryonic matter.

Dragan Slavkov Hajdukovic

2008-10-19T23:59:59.000Z

222

Higgs Boson Production and Weak Boson Structure  

E-Print Network (OSTI)

The influence of the QCD structure of the weak bosons on the Higgs boson production in $e$-$p$ scattering is studied. The energy and Higgs boson mass dependence of the cross-section, following from the new contributions, is calculated.

Wojciech Slominski; Jerzy Szwed

1995-07-18T23:59:59.000Z

223

X-ray and optical flux ratio anomalies in quadruply lensed quasars. II. Mapping the dark matter content in elliptical galaxies  

E-Print Network (OSTI)

We present a microlensing analysis of 61 Chandra observations of 14 quadruply lensed quasars. X-ray flux measurements of the individual quasar images give a clean determination of the microlensing effects in the lensing ...

Pooley, David

224

Fully coherent follow-up of continuous gravitational-wave candidates  

E-Print Network (OSTI)

The search for continuous gravitational waves from unknown isolated sources is computationally limited due to the enormous parameter space that needs to be covered and the weakness of the expected signals. Therefore semi-coherent search strategies have been developed and applied in distributed computing environments such as Einstein@Home, in order to narrow down the parameter space and identify interesting candidates. However, in order to optimally confirm or dismiss a candidate as a possible gravitational-wave signal, a fully-coherent follow-up using all the available data is required. We present a general method and implementation of a direct (2-stage) transition to a fully-coherent follow-up on semi-coherent candidates. This method is based on a grid-less Mesh Adaptive Direct Search (MADS) algorithm using the F-statistic. We demonstrate the detection power and computing cost of this follow-up procedure using extensive Monte-Carlo simulations on (simulated) semi-coherent candidates from a directed as well a...

Shaltev, Miroslav

2013-01-01T23:59:59.000Z

225

Fully coherent follow-up of continuous gravitational-wave candidates  

E-Print Network (OSTI)

The search for continuous gravitational waves from unknown isolated sources is computationally limited due to the enormous parameter space that needs to be covered and the weakness of the expected signals. Therefore semi-coherent search strategies have been developed and applied in distributed computing environments such as Einstein@Home, in order to narrow down the parameter space and identify interesting candidates. However, in order to optimally confirm or dismiss a candidate as a possible gravitational-wave signal, a fully-coherent follow-up using all the available data is required. We present a general method and implementation of a direct (2-stage) transition to a fully-coherent follow-up on semi-coherent candidates. This method is based on a grid-less Mesh Adaptive Direct Search (MADS) algorithm using the F-statistic. We demonstrate the detection power and computing cost of this follow-up procedure using extensive Monte-Carlo simulations on (simulated) semi-coherent candidates from a directed as well as from an all-sky search setup.

Miroslav Shaltev; Reinhard Prix

2013-03-11T23:59:59.000Z

226

IIR Adaptive Filters for Detection of Gravitational Waves from Coalescing Binaries  

E-Print Network (OSTI)

In this paper we propose a new strategy for gravitational waves detection from coalescing binaries, using IIR Adaptive Line Enhancer (ALE) filters. This strategy is a classical hierarchical strategy in which the ALE filters have the role of triggers, used to select data chunks which may contain gravitational events, to be further analyzed with more refined optimal techniques, like the the classical Matched Filter Technique. After a direct comparison of the performances of ALE filters with the Wiener-Komolgoroff optimum filters (matched filters), necessary to discuss their performance and to evaluate the statistical limitation in their use as triggers, we performed a series of tests, demonstrating that these filters are quite promising both for the relatively small computational power needed and for the robustness of the algorithms used. The performed tests have shown a weak point of ALE filters, that we fixed by introducing a further strategy, based on a dynamic bank of ALE filters, running simultaneously, but started after fixed delay times. The results of this global trigger strategy seems to be very promising, and can be already used in the present interferometers, since it has the great advantage of requiring a quite small computational power and can easily run in real-time, in parallel with other data analysis algorithms.

F. Acernese; F. Barone; R. De Rosa; A. Eleuteri; L. Giordano; L. Milano

2004-04-07T23:59:59.000Z

227

Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors  

E-Print Network (OSTI)

The main goal of the AEgIS experiment at CERN is to test the weak equivalence principle for antimatter. AEgIS will measure the free-fall of an antihydrogen beam traversing a moir\\'e deflectometer. The goal is to determine the gravitational acceleration g for antihydrogen with an initial relative accuracy of 1% by using an emulsion detector combined with a silicon micro-strip detector to measure the time of flight. Nuclear emulsions can measure the annihilation vertex of antihydrogen atoms with a precision of about 1 - 2 microns r.m.s. We present here results for emulsion detectors operated in vacuum using low energy antiprotons from the CERN antiproton decelerator. We compare with Monte Carlo simulations, and discuss the impact on the AEgIS project.

AEgIS Collaboration; S. Aghion; O. Ahlén; C. Amsler; A. Ariga; T. Ariga; A. S. Belov; G. Bonomi; P. Bräunig; J. Bremer; R. S. Brusa; L. Cabaret; C. Canali; R. Caravita; F. Castelli; G. Cerchiari; S. Cialdi; D. Comparat; G. Consolati; J. H. Derking; S. Di Domizio; L. Di Noto; M. Doser; A. Dudarev; A. Ereditato; R. Ferragut; A. Fontana; P. Genova; M. Giammarchi; A. Gligorova; S. N. Gninenko; S. Haider; J. Harasimovicz; S. D. Hogan; T. Huse; E. Jordan; L. V. Jřrgensen; T. Kaltenbacher; J. Kawada; A. Kellerbauer; M. Kimura; A. Knecht; D. Krasnický; V. Lagomarsino; A. Magnani; S. Mariazzi; V. A. Matveev; F. Moia; G. Nebbia; P. Nédélec; M. K. Oberthaler; N. Pacifico; V. Petrácek; C. Pistillo; F. Prelz; M. Prevedelli; C. Regenfus; C. Riccardi; O. Rřhne; A. Rotondi; H. Sandaker; P. Scampoli; A. Sosa; J. Storey; M. A. Subieta Vasquez; M. Spacek; G. Testera; D. Trezzi; R. Vaccarone; C. P. Welsch; S. Zavatarelli

2013-06-24T23:59:59.000Z

228

LISA-2020: An Intermediate Scale Space Gravitational Wave Observatory for This Decade  

E-Print Network (OSTI)

Over the last three decades, an exceptionally good science case has been made for pursuing gravitational wave (GW) astronomy. This has engendered a worldwide effort to detect the extremely weak signals generated by expected sources. With the next round of upgrades the ground based instruments are likely to make the first detections of the sources, and a new era of astronomy will begin, possibly as early as 2017. Inconveniently, due to seismic noise and baseline length issues, the low frequency (2030 now seems very unlikely. This paper examines the case for a scaled down mission that is comparable in cost and duration to medium scale astrophysics missions such as the 1978 ($630M) Einstein (HEAO 2) x-ray Observatory...

Buchman, S; Byer, R L; DeBra, D; Balakrishnan, K; Cutler, G Dufresne; Al-Fauwaz, A; Hultgren, E; Al-Jadaan, A K; Saraf, S; Tan, S; Al-Thubiti, S; Zoellner, A

2013-01-01T23:59:59.000Z

229

On the nature of gravitational forces  

E-Print Network (OSTI)

In this paper I show how the statistics of the gravitational field is changed when the system is characterized by a non-uniform distribution of particles. I show how the distribution functions W(dF/dt) giving the joint probability that a test particle is subject to a force F and an associated rate of change of F given by dF/dt, are modified by inhomogeneity. Then I calculate the first moment of dF/dt to study the effects of inhomogenity on dynamical friction. Finally I test, by N-Body simulations, that the theoretical W(F) and dF/dt describes correctly the experimental data and I find that the stochastic force distribution obtained for the evolved system is in good agreement with theory. Moreover, I find that in an inhomogeneous background the friction force is actually enhanced relative to the homogeneous case.

A. Del Popolo

2008-01-07T23:59:59.000Z

230

On the nature of gravitational forces  

E-Print Network (OSTI)

In this paper I show how the statistics of the gravitational field is changed when the system is characterized by a non-uniform distribution of particles. I show how the distribution functions W(dF/dt) giving the joint probability that a test particle is subject to a force F and an associated rate of change of F given by dF/dt, are modified by inhomogeneity. Then I calculate the first moment of dF/dt to study the effects of inhomogenity on dynamical friction. Finally I test, by N-Body simulations, that the theoretical W(F) and dF/dt describes correctly the experimental data and I find that the stochastic force distribution obtained for the evolved system is in good agreement with theory. Moreover, I find that in an inhomogeneous background the friction force is actually enhanced relative to the homogeneous case.

Del Popolo, A

2008-01-01T23:59:59.000Z

231

A Characteristic Extraction Tool for Gravitational Waveforms  

E-Print Network (OSTI)

We develop and calibrate a characteristic waveform extraction tool whose major improvements and corrections of prior versions allow satisfaction of the accuracy standards required for advanced LIGO data analysis. The extraction tool uses a characteristic evolution code to propagate numerical data on an inner worldtube supplied by a 3+1 Cauchy evolution to obtain the gravitational waveform at null infinity. With the new extraction tool, high accuracy and convergence of the numerical error can be demonstrated for an inspiral and merger of mass M binary black holes even for an extraction worldtube radius as small as R = 20M. The tool provides a means for unambiguous comparison between waveforms generated by evolution codes based upon different formulations of the Einstein equations and based upon different numerical approximations.

M. C. Babiuc; B. Szilagyi; J. Winicour; Y. Zlochower

2010-11-18T23:59:59.000Z

232

Quantum Gravitational Uncertainty of Transverse Position  

E-Print Network (OSTI)

It is argued that holographic bounds on the information content of spacetime might be directly measurable. A new uncertainty principle is conjectured to arise from quantum indeterminacy of nearly flat spacetime: Angular orientations of null trajectories of spatial length L are uncertain, with standard deviation in each transverse direction \\Delta \\theta> \\sqrt{l_P/L}, where l_p denotes the Planck length. It is shown that this angular uncertainty corresponds to the information loss and nonlocality that occur if 3+1-D spacetime has a holographic dual description in terms of Planck-scale waves on a 2+1D screen with encoding close to the Planck diffraction limit, and agrees with covariant holographic entropy bounds on total number of degrees of freedom. The spectrum and spatial structure of predicted quantum-gravitational ``holographic noise'' are estimated to be directly measurable over a broad range of frequencies using interferometers with current technology.

Craig J. Hogan

2007-03-29T23:59:59.000Z

233

Geometric Boundary Data for the Gravitational Field  

E-Print Network (OSTI)

An outstanding issue in the treatment of boundaries in general relativity is the lack of a local geometric interpretation of the necessary boundary data. For the Cauchy problem, the initial data is supplied by the 3-metric and extrinsic curvature of the initial Cauchy hypersurface.. This Cauchy data determines a solution to Einstein's equations which is unique up to a diffeomorphism. Here, we show how three pieces of boundary data, which are associated locally with the geometry of the boundary, likewise determine a solution of the initial-boundary value problem which is unique up to a diffeomorphism. One piece of this data, constructed from the extrinsic curvature of the boundary, determines the dynamical evolution of the boundary. The other two pieces constitute a conformal class of rank-2, positive definite metrics, which represent the two gravitational degrees of freedom.

H-O. Kreiss; J. Winicour

2013-02-04T23:59:59.000Z

234

Massless Limit of Gravitational Higgs Mechanism  

E-Print Network (OSTI)

In gravitational Higgs mechanism graviton components acquire mass via spontaneous diffeomorphism breaking by scalar vacuum expectation values. We point out that in the massless limit the resulting theory is not Einstein-Hilbert gravity (EHG) but constrained gravity (CG). Consequently, massive solutions in the massless limit must be compared to those in CG (as opposed to EHG). We discuss spherically symmetric solutions in this context. The Schwarzschild solution in EHG can be coordinate-transformed such that it is also a solution in CG. The resulting solutions are non-perturbative in the asymptotic regime, and are reproduced in the massless limit of asymptotic massive solutions, hence no van Dam-Veltman-Zakharov discontinuity. We point out that higher curvature terms must be included to obtain non-singular spherically symmetric massive solutions and discuss a suitable framework.

Zurab Kakushadze

2007-11-02T23:59:59.000Z

235

Spontaneous breaking of conformal invariance, solitons and gravitational waves in theories of conformally invariant gravitation  

E-Print Network (OSTI)

We study conformal gravity as an alternative theory of gravitation. For conformal gravity to be phenomenologically viable requires that the conformal symmetry is not manifest at the energy scales of the other known physical forces. Hence we require a mechanism for the spontaneous breaking of conformal invariance. In this paper we study the possibility that conformal invariance is spontaneously broken due to interactions with conformally coupled matter fields. The vacuum of the theory admits conformally non-invariant solutions corresponding to maximally symmetric space-times and variants thereof. These are either de Sitter space-time or anti-de Sitter space-time in the full four space-time dimensions or in a lower dimensional sub-space. We consider in particular normalizable, linearized gravitational perturbations around the anti-de Sitter background. Exploiting the conformal flatness of this space-time, we show to second order, that these gravitational fluctuations, that are taken to be fourier decomposable, carry zero energy-momentum. This squares well with the theorem that asymptotically flat space-times conformal gravity contain zero energy and momentum \\cite{bhs}. We also show the possibility of domain wall solitons interpolating between the ground states of spontaneously broken conformal symmetry that we have found. These solitons necessarily require the vanishing of the scalar field, repudiating the recent suggestion \\cite{f} that the conformal symmetry could be quarantined to a sterile sector of the theory by choosing an appropriate field redefinition.

Jihene Bouchami; M. B. Paranjape

2007-10-29T23:59:59.000Z

236

Integration of diffractive lenses with addressable vertical-cavity laser arrays  

Science Conference Proceedings (OSTI)

An optical interconnection system is being developed to provide vertical, digital data channels for stacked multichip modules. A key component of the system is an array of individually addressable vertical-cavity surface-emitting lasers with diffractive lenses integrated into the substrate to control beam divergence and direction. The lenses were fabricated by direct-write e-beam lithography and reactive ion beam etching into the GaAs substrate. Preliminary device performance data and the design and fabrication issues are discussed.

Warren, M.E.; Du, T.C.; Wendt, J.R.; Vawter, G.A.; Carson, R.F.; Lear, K.L.; Kilcoyne, S.P.; Schneider, R.P.; Zolper, J.C.

1995-04-01T23:59:59.000Z

237

Gravitational-wave astronomy: the high-frequency window  

E-Print Network (OSTI)

This contribution is divided in two parts. The first part provides a text-book level introduction to gravitational radiation. The key concepts required for a discussion of gravitational-wave physics are introduced. In particular, the quadrupole formula is applied to the anticipated ``bread-and-butter'' source for detectors like LIGO, GEO600, EGO and TAMA300: inspiralling compact binaries. The second part provides a brief review of high frequency gravitational waves. In the frequency range above (say) 100Hz, gravitational collapse, rotational instabilities and oscillations of the remnant compact objects are potentially important sources of gravitational waves. Significant and unique information concerning the various stages of collapse, the evolution of protoneutron stars and the details of the supranuclear equation of state of such objects can be drawn from careful study of the gravitational-wave signal. As the amount of exciting physics one may be able to study via the detections of gravitational waves from these sources is truly inspiring, there is strong motivation for the development of future generations of ground based detectors sensitive in the range from hundreds of Hz to several kHz.

Nils Andersson; Kostas D Kokkotas

2004-03-20T23:59:59.000Z

238

Weak Viscoelastic Nematodynamics of Maxwell Type  

E-Print Network (OSTI)

A constitutive theory for weak viscoelastic nematodynamics of Maxwell type is developed using the standard local approach of non-equilibrium thermodynamics. Along with particular viscoelastic and nematic kinematics, the theory uses the weakly elastic potential proposed by de Gennes for nematic solids and the LEP constitutive equations for viscous nematic liquids, while ignoring the Frank (orientation) elasticity and inertia effects. In spite of many basic parameters, algebraic properties of nematic operations investigated in Appendix, allowed us to reveal a general group structure of the theory and present it in a simple form. It is shown that the evolution equation for director is also viscoelastic. An example of magnetization clarifies the situation with non-symmetric stresses. When the sources of stress asymmetry are absent, the theory is simplified and its relaxation properties are described by a symmetric subgroup of nematic algebraic operations. A purely linear constitutive behavior exemplifies the symmetric situation.

Arkady I. Leonov; Valery S. Volkov

2004-08-26T23:59:59.000Z

239

Teleparallel Gravity and the Gravitational Energy-Momentum Density  

E-Print Network (OSTI)

In the context of the teleparallel equivalent of general relativity, we show that the energy-momentum density for the gravitational field can be described by a true spacetime tensor. It is also invariant under local (gauge) translations of the tangent space coordinates, but transforms covariantly only under global Lorentz transformations. When the gauge gravitational field equation is written in a purely spacetime form, it becomes the teleparallel equivalent of Einstein's equation, and we recover M{\\o}ller's expression for the canonical gravitational energy-momentum pseudotensor.

V. C. de Andrade; L. C. T. Guillen; J. G. Pereira

2000-11-22T23:59:59.000Z

240

Correlation between Gamma-Ray bursts and Gravitational Waves  

E-Print Network (OSTI)

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.

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

2001-01-05T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Influence of geomagnetic perturbation on resonant gravitational wave detector  

E-Print Network (OSTI)

The level of background signals in modern cryogenic resonant mass gravitational wave antenna is discussed caused by (a) the geomagnetic field pulsations and (b) an atmosferic of very low frequency band, generated by a lightning flash. The analysis of our results show that the signals of this origin will generally exceed the signals from the gravitational wave sources. To suppress these artifacts in such gravitational antenna, it is necessary to use the magnetometer included as anti-coincidence protection and a system of magnetic screens.

Peter Vorob'ev; Valeri Ianovski; Igor Okunev

1996-02-12T23:59:59.000Z

242

Cerenkov radiation by charged particles in an external gravitational field  

E-Print Network (OSTI)

Charged particles in the geodesic trajectory of an external gravitational field do not emit electromagnetic radiation. This is expected from the application of the equivalence principle. We show here that charged particles propagating in an external gravitational field with non-zero components of the Ricci tensor can emit radiation by the \\v{C}erenkov process. The external gravitational field acts like an effective refractive index for light. Since the Ricci tensor cannot be eliminated by a change of coordinates, there is no violation of the equivalence principle in this process.

Anshu Gupta; Subhendra Mohanty; Manoj K. Samal

1995-09-05T23:59:59.000Z

243

Upper Limits on a Stochastic Background of Gravitational Waves  

E-Print Network (OSTI)

The Laser Interferometer Gravitational Wave Observatory (LIGO) has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of Omega_0<8.4e-4 in the 69-156 Hz band is ~10^5 times lower than the previous result in this frequency range.

Abbott, B; Adhikari, R; Ageev, A; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Ashley, M; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, C; Barker, D; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff, S J; Betzwieser, J; Bhawal, B; Bilenko, I A; Billingsley, G; Black, E; Blackburn, K; Blackburn, L; Bland, B; Bochner, B; Bogue, L; Bork, R; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brown, D A; Bullington, A; Bunkowski, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Cokelaer, T; Colacino, C; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Daw, E; De Bra, D; Delker, T; Dergachev, V; DeSalvo, R; Dhurandhar, S V; Di Credico, A; Ding, H; Drever, R W P; Dupuis, R J; Edlund, J A; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fairhurst, S; Fallnich, C; Farnham, D; Fejer, M M; Findley, T; Fine, M; Finn, L S; Franzen, K Y; Freise, A; Frey, R; Fritschel, P; Frolov, V V; Fyffe, M; Ganezer, K S; Garofoli, J; Giaime, J A; Gillespie, A; Goda, K; González, G; Goler, S; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Günther, M; Gustafson, E; Gustafson, R; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harms, J; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hild, S; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, B; Johnson, W W; Johnston, W R; Jones, D I; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonor, I; Libbrecht, K; Libson, A; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Luck, H; Lyons, T T; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNabb, J W C; Mendell, G; Mercer, R A; Meshkov, S; Messaritaki, E; Messenger, C; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Müller, G; Mukherjee, S; Murray, P; Myers, J; Nagano, S; Nash, T; Nayak, R; Newton, G; Nocera, F; Noel, J S; Nutzman, P; Olson, T; O'Reilly, B; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Pan, Y; Papa, M A; Parameshwaraiah, V; Parameswariah, C; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Prix, R; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Rawlins, K; Ray-Majumder, S; Re, V; Redding, D; Regehr, M W; Regimbau, T; Reid, S; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rivera, B; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Rüdiger, A; Russell, P; Ryan, K; Salzman, I; Sandberg, V; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Seader, S E; Searle, A C; Sears, B; Seel, S; Seifert, F; Sengupta, A S; Shapiro, C A; Shawhan, P; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Smith, J R; Smith, M; Smith, M R; Sneddon, P H; Spero, R; Stapfer, G; Steussy, D; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Taylor, R; Thorne, K A; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Tyler, W; Ugolini, D W; Ungarelli, C; Vallisneri, M; Van Putten, M H P M; Vass, S; Vecchio, A; Veitch, J; Vorvick, C; Vyachanin, S P; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Wiley, S; Wilkinson, C; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Wu, W; Yakushin, I; Yamamoto, H; Yoshida, S; Zaleski, K D; Zanolin, M; Zawischa, I; Zhang, L; Zhu, R; Zotov, N P; Zucker, M; Zweizig, J

2005-01-01T23:59:59.000Z

244

Stopping power of weakly unstable plasmas  

SciTech Connect

An expression for the additional contribution to the stopping power of a weakly unstable plasma due to the modification of the beam--plasma collision operator by the presence of the unstable modes is derived and evaluated for a plasma with a flowing hot-electron tail, i.e., a bump-on-tail instability. It is found that the unstable plasma oscillations do not substantially alter the screening of the beam--plasma interaction.

Perez, J.D.; Payne, G.L.

1984-02-01T23:59:59.000Z

245

Summary of the Hadronic Weak Interaction session  

Science Conference Proceedings (OSTI)

We summarize and discuss present and future experiments on decays of light mesons and muons that were presented in the Hadronic Weak Interaction working group session of the ``Workshop on Future Directions in Particle and Nuclear Physics at Multi-GeV Hadron Facilities.`` Precise measurements and rare-decay searches, which sense mass scales in the 1--1000 TeV region, are discussed in the context of the standard model and beyond.

Bock, G. [Fermi National Accelerator Lab., Batavia, IL (United States); Bryman, D.A.; Numao, T. [British Columbia Univ., Vancouver, BC (Canada). TRIUMF Facility

1993-07-01T23:59:59.000Z

246

Heat capacity in weakly correlated liquids  

Science Conference Proceedings (OSTI)

Previously unavailable numerical data related to the heat capacity in two- and three-dimensional liquid Yukawa systems are obtained by means of fluctuation theory. The relations between thermal conductivity and diffusion constants are numerically studied and discussed. New approximation for heat capacity dependence on non-ideality parameter for weakly correlated systems of particles is proposed. Comparison of the obtained results to the existing theoretical and numerical data is discussed.

Khrustalyov, Yu. V.; Vaulina, O. S. [Joint Institute for High Temperatures RAS, 125412, Izhorskaya St., 13 bld.2, Moscow (Russian Federation); Moscow Institute of Physics and Technology, 117303, Kerchenskaya St., 1A bld.1, Moscow (Russian Federation); Koss, X. G. [Joint Institute for High Temperatures RAS, 125412, Izhorskaya St., 13 bld.2, Moscow (Russian Federation)

2012-12-15T23:59:59.000Z

247

Higgs Quantum Numbers in Weak Boson Fusion  

E-Print Network (OSTI)

Recently, the ATLAS and CMS experiments have reported the discovery of a Higgs like resonance at the LHC. The next analysis step will include the determination of its spin and CP quantum numbers or the form of its interaction Lagrangian channel-by-channel. We show how weak-boson-fusion Higgs production and associated ZH production can be used to separate different spin and CP states.

C. Englert; D. Goncalves-Netto; K. Mawatari; T. Plehn

2012-12-04T23:59:59.000Z

248

Formation of ice lenses and frost heave A. W. Rempel1  

E-Print Network (OSTI)

are promoted by the influence of mineral surfaces on the phase behavior of ice. A large body of experimental, but nevertheless ad hoc parameterizations for the ice particle interactions, the choice of functional form beingFormation of ice lenses and frost heave A. W. Rempel1 Received 13 April 2006; revised 26 January

Rempel, Alan W.

249

Gradient-Index (GRIN) lenses by Slurry-based Three-Dimensional Printing (S-3DP)  

E-Print Network (OSTI)

GRIN lenses with vertical index variation and radial index variation have been successfully fabricated using S-3DPTM. Two silica-based material systems, A1203-SiO? and BaO-SiO?, have been studied and used for the fabrication ...

Wang, Hong-Ren, 1973-

2005-01-01T23:59:59.000Z

250

Numerical tests of dynamical friction in gravitational inhomogeneous systems  

E-Print Network (OSTI)

In this paper, I test by numerical simulations the results of Del Popolo & Gambera (1998),dealing with the extension of Chandrasekhar and von Neumann's analysis of the statistics of the gravitational field to systems in which particles (e.g., stars, galaxies) are inhomogeneously distributed. The paper is an extension of that of Ahmad & Cohen (1974), in which the authors tested some results of the stochastic theory of dynamical friction developed by Chandrasekhar & von Neumann (1943) in the case of homogeneous gravitational systems. It is also a continuation of the work developed in Del Popolo (1996a,b), which extended the results of Ahmad & Cohen (1973), (dealing with the study of the probability distribution of the stochastic force in homogeneous gravitational systems) to inhomogeneous gravitational systems. Similarly to what was done by Ahmad & Cohen (1974) in the case of homogeneous systems, I test, by means of the evolution of an inhomogeneous system of particles, that the theoretical ...

Popolo, A D

2003-01-01T23:59:59.000Z

251

A Gravitational Spreading Origin For The Socompa Debris Avalanche | Open  

Open Energy Info (EERE)

Gravitational Spreading Origin For The Socompa Debris Avalanche Gravitational Spreading Origin For The Socompa Debris Avalanche Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Gravitational Spreading Origin For The Socompa Debris Avalanche Details Activities (0) Areas (0) Regions (0) Abstract: Socompa Volcano arguably provides the world's best-exposed example of a sector collapse-derived debris avalanche deposit. New observations lead us to re-interpret the origin of the sector collapse. We show that it was triggered by failure of active thrust-anticlines in sediments and ignimbrites underlying the volcano. The thrust-anticlines were a result of gravitational spreading of substrata under the volcano load. About 80% of the resulting avalanche deposit is composed of substrata formerly residing under the volcano and in the anticlines. The collapse

252

Sensitivity Studies for Third-Generation Gravitational Wave Observatories  

E-Print Network (OSTI)

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.

S. Hild; M. Abernathy; F. Acernese; P. Amaro-Seoane; N. Andersson; K. Arun; F. Barone; B. Barr; M. Barsuglia; M. Beker; N. Beveridge; S. Birindelli; S. Bose; L. Bosi; S. Braccini; C. Bradaschia; T. Bulik; E. Calloni; G. Cella; E. Chassande Mottin; S. Chelkowski; A. Chincarini; J. Clark; E. Coccia; C. Colacino; J. Colas; A. Cumming; L. Cunningham; E. Cuoco; S. Danilishin; K. Danzmann; R. De Salvo; T. Dent; R. De Rosa; L. Di Fiore; A. Di Virgilio; M. Doets; V. Fafone; P. Falferi; R. Flaminio; J. Franc; F. Frasconi; A. Freise; D. Friedrich; P. Fulda; J. Gair; G. Gemme; E. Genin; A. Gennai; A. Giazotto; K. Glampedakis; C. Gräf; M. Granata; H. Grote; G. Guidi; A. Gurkovsky; G. Hammond; M. Hannam; J. Harms; D. Heinert; M. Hendry; I. Heng; E. Hennes; J. Hough; S. Husa; S. Huttner; G. Jones; F. Khalili; K. Kokeyama; K. Kokkotas; B. Krishnan; T. G. F. Li; M. Lorenzini; H. Lück; E. Majorana; I. Mandel; V. Mandic; M. Mantovani; I. Martin; C. Michel; Y. Minenkov; N. Morgado; S. Mosca; B Mours; H. Müller-Ebhardt; P. Murray; R. Nawrodt; J. Nelson; R. Oshaughnessy; C. D. Ott; C. Palomba; A. Paoli; G. Parguez; A. Pasqualetti; R. Passaquieti; D. Passuello; L. Pinard; W. Plastino; R. Poggiani1; P. Popolizio; M. Prato; M. Punturo; P. Puppo; D. Rabeling; P. Rapagnani; J. Read; T. Regimbau; H. Rehbein; S. Reid; F. Ricci; F. Richard; A. Rocchi; S. Rowan; A. Rüdiger; L. Santamaría; B. Sassolas; B. Sathyaprakash; R. Schnabel; C. Schwarz; P. Seidel; A. Sintes; K. Somiya; F. Speirits; K. Strain; S Strigin; P. Sutton; S. Tarabrin; A. Thüring; J. van den Brand; M. van Veggel; C. van den Broeck; A. Vecchio; J. Veitch; F. Vetrano; A. Vicere; S. Vyatchanin; B. Willke; G. Woan; K. Yamamoto

2010-12-04T23:59:59.000Z

253

Open Issues in the search for gravitational wave transients  

E-Print Network (OSTI)

The LIGO-Virgo network of kilometer-scale laser interferometric gravitational-wave detectors reached a major milestone with the successful operation of LIGO's fifth (S5) and Virgo's first (VSR1) science runs during 2005-2007. ...

Blackburn, Lindy L

2010-01-01T23:59:59.000Z

254

Polarized Gravitational Waves from Gamma-Ray Bursts  

E-Print Network (OSTI)

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.

Shiho Kobayashi; Peter Meszaros

2002-12-25T23:59:59.000Z

255

Gravitational Wave Memory of Gamma-Ray Burst Jets  

E-Print Network (OSTI)

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.

Norichika Sago; Kunihito Ioka; Takashi Nakamura; Ryo Yamazaki

2004-05-13T23:59:59.000Z

256

A study of the gravitational wave form from pulsars  

E-Print Network (OSTI)

We present analytical and numerical studies of the Fourier transform (FT) of the gravitational wave (GW) signal from a pulsar,taking into account the rotation of the Earth for a one day observation period.

S. R. Valluri; F. A. Chishtie; R. G. Biggs; M. Davison; Sanjeev V. Dhurandhar; B. S. Sathyaprakash

2000-12-01T23:59:59.000Z

257

Variational formulation of two scalar-tetradic theories of gravitation  

Science Conference Proceedings (OSTI)

In this paper we obtain two scalar-tetradic theories of gravitation (theories A and B) from a variational principle. In these theories the gravitational energy is localized and the principle of equivalence holds. They combine some aspects of Moller theory and the Brans-Dicke theory. The first-order approximations and an introduction to the study of both theories in the static spherically symmetric case are presented.

Saez, D.

1983-06-15T23:59:59.000Z

258

Fluid/Gravity Correspondence, Second Order Transport and Gravitational Anomaly  

E-Print Network (OSTI)

We study the transport properties of a relativistic fluid affected by chiral and gauge-gravitational anomalies. The computation is performed in the framework of the fluid/gravity correspondence for a 5 dim holographic model with Chern-Simons terms in the action. We find new anomalous and non anomalous transport coefficients, as well as new contributions to the existing ones coming from the mixed gauge-gravitational anomaly. Consequences for the shear waves dispersion relation are analyzed.

Eugenio Megias; Francisco Pena-Benitez

2013-07-29T23:59:59.000Z

259

An alternative method for calculating the energy of gravitational waves  

E-Print Network (OSTI)

In the expansive nondecelerative universe model, creation of matter occurs due to which the Vaidya metrics is applied. This fact allows for localizing gravitational energy and calculating the energy of gravitational waves using an approach alternative to the well established procedure based on quadrupole formula. Rationalization of the gradual increase in entropy of the Universe using relation describing the total curvature of space-time is given too.

Miroslav Sukenik; Jozef Sima

1999-09-21T23:59:59.000Z

260

Search for gravitational wave bursts in LIGO's third science run  

E-Print Network (OSTI)

We report on a search for gravitational wave bursts in data from the three LIGO interferometric detectors during their third science run. The search targets subsecond bursts in the frequency range 100-1100 Hz for which no waveform model is assumed, and has a sensitivity in terms of the root-sum-square (rss) strain amplitude of hrss ~ 10^{-20} / sqrt(Hz). No gravitational wave signals were detected in the 8 days of analyzed data.

LIGO Scientific Collaboration

2005-11-27T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

The Optical Gravitational Lensing Experiment. Internet Access to the OGLE Photometry Data Set: OGLE-II BVI maps and I-band data  

E-Print Network (OSTI)

We present on-line, interactive interface to the whole I-band photometry data set obtained in the second phase of the OGLE project (OGLE-II). The raw photometric database is accessed through an additional database using MySQL engine, allowing to select objects fulfilling any set of criteria including RA/Dec coordinates, mean brightness, error etc. The results of the queries can be browsed on-line, the light curves can be plotted interactively, the photometric data can be downloaded for the total of over 10^10 measurements of more than 40 million objects in the Galactic bulge and the Magellanic Clouds collected during OGLE-II. The MySQL database of parameters also includes the complete data set of the previously published photometric BVI maps of OGLE-II targets, allowing to interactively select objects from these maps.

M. K. Szymanski

2006-02-01T23:59:59.000Z

262

The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. VII. Classical Cepheids in the Small Magellanic Cloud  

E-Print Network (OSTI)

The seventh part of the OGLE-III Catalog of Variable Stars (OIII-CVS) consists of 4630 classical Cepheids in the Small Magellanic Cloud (SMC). The sample includes 2626 fundamental-mode (F), 1644 first-overtone (1O), 83 second-overtone (2O), 59 double-mode F/1O, 215 double-mode 1O/2O, and 3 triple-mode classical Cepheids. For each object basic parameters, multi-epoch VI photometry collected within 8 or 13 years of observations, and finding charts are provided in the OGLE Internet archive. We present objects of particular interest: exceptionally numerous sample of single-mode second-overtone pulsators, five double Cepheids, two Cepheids with eclipsing variations superimposed on the pulsation light curves. At least 139 first-overtone Cepheids exhibit low-amplitude secondary variations with periods in the range 0.60-0.65 of the primary ones. These stars populate three distinct sequences in the Petersen diagram. The origin of this secondary modulation is still unknown. Contrary to the Large Magellanic Cloud (LMC) ...

Soszynski, I; Udalski, A; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L; Szewczyk, O; Ulaczyk, K

2010-01-01T23:59:59.000Z

263

The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XI. RR Lyrae Stars in the Galactic Bulge  

E-Print Network (OSTI)

The eleventh part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains 16836 RR Lyr stars detected in the OGLE fields toward the Galactic bulge. The total sample is composed of 11756 RR Lyr stars pulsating in the fundamental mode (RRab), 4989 overtone pulsators (RRc), and 91 double-mode (RRd) stars. About 400 RR Lyr stars are members of the Sagittarius Dwarf Spheroidal Galaxy. The catalog includes the time-series photometry collected in the course of the OGLE survey, basic parameters of the stars, finding charts, and cross-identifications with other catalogs of RR Lyr stars toward the Milky Way center. We notice that some RRd stars in the Galactic bulge show unusually short periods and small ratio of periods, down to P_F=0.35 days and P_1O/P_F=0.726. In the Petersen diagram double-mode RR Lyr stars form a parabola-like structure, which connects shorter- and longer-period RRd stars. We show that the unique properties of the bulge RRd stars may be explained by allowing for the wide range of the metal a...

Soszynski, I; Udalski, A; Poleski, R; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L; Ulaczyk, K; Kozlowski, S; Pietrukowicz, P

2011-01-01T23:59:59.000Z

264

The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XIV. Classical and Type II Cepheids in the Galactic Bulge  

E-Print Network (OSTI)

The fourteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains Cepheid variables detected in the OGLE-II and OGLE-III fields toward the Galactic bulge. The catalog is divided into two main categories: 32 classical Cepheids (21 single-mode fundamental-mode F, four first-overtone 1O, two double-mode F/1O, three double-mode 1O/2O and two triple-mode 1O/2O/3O pulsators) and 335 type II Cepheids (156 BL Her, 128 W Vir and 51 RV Tau stars). Six of the type II Cepheids likely belong to the Sagittarius Dwarf Spheroidal Galaxy. The catalog data include the time-series photometry collected in the course of the OGLE survey, observational parameters of the stars, finding charts, and cross-identifications with the General Catalogue of Variable Stars. We discuss some statistical properties of the sample and compare it with the OGLE catalogs of Cepheids in the Large and Small Magellanic Clouds. Multi-mode classical Cepheids in the Galactic bulge show systematically smaller period ratios than their counter...

Soszynski, I; Pietrukowicz, P; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L; Ulaczyk, K; Poleski, R; Kozlowski, S

2011-01-01T23:59:59.000Z

265

The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. III. RR Lyrae Stars in the Large Magellanic Cloud  

E-Print Network (OSTI)

The third part of the OGLE-III Catalog of Variable Stars comprises 24906 RR Lyr stars in the Large Magellanic Cloud (LMC). This sample consist of 17693 fundamental-mode (RRab), 4958 first-overtone (RRc), 986 double-mode (RRd) and 1269 suspected second-overtone (RRe) pulsators. 66 objects are foreground Galactic RR Lyr stars. The catalog data include basic photometric and astrometric properties of the RR Lyr stars, multi-epoch VI photometry and finding charts. We detected one new RR Lyr star with additional eclipsing variations. The spatial distribution of RR Lyr stars in the LMC is distinctly non-spherical and it is elongated in the same direction as the LMC bar. The basic statistical features of RR Lyr stars in the LMC are provided. The apparent V-band magnitudes for RRab stars have the modal value at 19.36 mag, and for overtone RR Lyr stars it is about 19.32 mag. The mean periods for RRab, RRc and RRe stars are 0.576, 0.337 and 0.270 days, respectively.

Soszynski, I; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L; Szewczyk, O; Ulaczyk, K; Poleski, R

2009-01-01T23:59:59.000Z

266

The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. IX. RR Lyrae Stars in the Small Magellanic Cloud  

E-Print Network (OSTI)

The ninth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) comprises RR Lyrae stars in the Small Magellanic Cloud (SMC). Our sample consists of 2475 variables, of which 1933 pulsate in the fundamental mode (RRab), 175 are the first overtone pulsators (RRc), 258 oscillate simultaneously in both modes (RRd) and 109 stars are suspected second-overtone pulsators (RRe). 30 objects are Galactic RR Lyr stars seen in the foreground of the SMC. We discuss some statistical features of the sample. Period distributions show distinct differences between SMC and LMC populations of RR Lyr variables, with the SMC stars having on average longer periods. The mean periods for RRab, RRc and RRe stars are 0.596, 0.366 and 0.293 days, respectively. The mean apparent magnitudes of RRab stars are equal to 19.70 mag in the V band and 19.12 mag in the I band. Spatial distribution of RR Lyr stars shows that the halo of the SMC is roughly round in the sky, however the density map reveals two maxima near the center of the SMC. F...

Soszynski, I; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L; Ulaczyk, K; Poleski, R

2010-01-01T23:59:59.000Z

267

Equilibrium thermodynamics in modified gravitational theories  

E-Print Network (OSTI)

We show that it is possible to obtain a picture of equilibrium thermodynamics on the apparent horizon in the expanding cosmological background for a wide class of modified gravity theories with the Lagrangian density $f(R, \\phi, X)$, where $R$ is the Ricci scalar and $X$ is the kinetic energy of a scalar field $\\phi$. This comes from a suitable definition of an energy momentum tensor of the "dark" component that respects to a local energy conservation in the Jordan frame. In this framework the horizon entropy $S$ corresponding to equilibrium thermodynamics is equal to a quarter of the horizon area $A$ in units of gravitational constant $G$, as in Einstein gravity. For a flat cosmological background with a decreasing Hubble parameter, $S$ globally increases with time, as it happens for viable $f(R)$ inflation and dark energy models. We also show that the equilibrium description in terms of the horizon entropy $S$ is convenient because it takes into account the contribution of both the horizon entropy $\\hat{S}$ in non-equilibrium thermodynamics and an entropy production term.

Kazuharu Bamba; Chao-Qiang Geng; Shinji Tsujikawa

2009-09-11T23:59:59.000Z

268

The Higgs sector of gravitational gauge theories  

E-Print Network (OSTI)

Gravitational gauge theories with de Sitter, Poincare and affine symmetry group are investigated under the aspect of the breakdown of the initial symmetry group down to the Lorentz subgroup. We review the theory of spontaneously broken de Sitter gravity by Stelle and West and apply a similar approach to the case of the Poincare and affine groups. Especially, we find that the groundstate of the metric affine theory leads to the determination of the Lorentzian signature of the metric in the groundstate. We show that the Higgs field remains in its groundstate, i.e., that the metric will have Lorentzian signature, unless we introduce matter fields that explicitely couple to the symmetric part of the connection. We also show that some features, like the necessity of the introduction of a dilaton field, that seem artificial in the context of the affine theory, appear most natural if the gauge group is taken to be the special linear group in five dimensions. Finally, we present an alternative model which is based on the spinor representation of the Lorentz group and is especially adopted to the description of spinor fields in a general linear covariant way, without the use of the infinite dimensional representations which are usually considered to be unavoidable.

M. Leclerc

2005-02-02T23:59:59.000Z

269

Supersymmetric Higgs Bosons in Weak Boson Fusion  

E-Print Network (OSTI)

We compute the complete supersymmetric next-to-leading order corrections to the production of a light Higgs boson in weak boson fusion. The size of the electroweak corrections is of similar order as the next-to-leading order corrections in the Standard Model. The supersymmetric QCD corrections turn out to be significantly smaller than their electroweak counterparts. These higher--order corrections are an important ingredient to a precision analysis of the (supersymmetric) Higgs sector at the LHC, either as a known correction factor or as a contribution to the theory error.

W. Hollik; T. Plehn; M. Rauch; H. Rzehak

2008-04-17T23:59:59.000Z

270

Analysis of spatial mode sensitivity of gravitational wave interferometer and targeted search for gravitational radiation from the Crab pulsar  

E-Print Network (OSTI)

Over the last several years the Laser Interferometer Gravitational Wave Observatory (LIGO) has been making steady progress in improving the sensitivities of its three interferometers, two in Hanford, Washington, and one ...

Betzwieser, Joseph (Joseph Charles)

2008-01-01T23:59:59.000Z

271

Weak Pressure Gradient Approximation and Its Analytical Solutions  

Science Conference Proceedings (OSTI)

A weak pressure gradient (WPG) approximation is introduced for parameterizing supradomain-scale (SDS) dynamics, and this method is compared to the relaxed form of the weak temperature gradient (WTG) approximation in the context of 3D, linearized, ...

David M. Romps

2012-09-01T23:59:59.000Z

272

Numerical Tests of the Weak Pressure Gradient Approximation  

Science Conference Proceedings (OSTI)

Cloud-resolving simulations of convection over a surface temperature hot spot are used to evaluate the weak pressure gradient (WPG) and weak temperature gradient (WTG) approximations. The premise of the relaxed form of WTG—that vertical velocity ...

David M. Romps

2012-09-01T23:59:59.000Z

273

Fatigue Weak-Link Density and Strength Distribution in High ...  

Science Conference Proceedings (OSTI)

Symposium, Fatigue and Corrosion Damage in Metallic Materials: Fundamentals, Modeling and Prevention. Presentation Title, Fatigue Weak-Link Density and ...

274

Prospects for Multiple Weak Gauge Boson Production at Supercollider Energies  

E-Print Network (OSTI)

We discuss the prospects for observing multiple weak gauge boson production at the SSC and LHC. We summarize conventional perturbative cross sections for processes involving 1-6 final state weak gauge bosons and compare them with more speculative scenarios including 1) a toy model of a strongly interacting Higgs sector patterned after hadronic multipion production and 2) the nonperturbative production of O(30) weak gauge bosons in a weakly coupled gauge sector.

D. A. Morris

1993-08-24T23:59:59.000Z

275

Composite Weak Bosons at the Large Hadron Collider  

E-Print Network (OSTI)

In a composite model of the weak bosons the excited bosons, in particular the p-wave bosons, are studied. The state with the lowest mass is identified with the boson, which has been discovered recently at the "Large Hadron Collider" at CERN. Specific properties of the excited weak bosons are studied, in particular their decays into weak bosons and into photons.

Harald Fritzsch

2013-07-24T23:59:59.000Z

276

Modeling active electrolocation in weakly electric fish  

E-Print Network (OSTI)

In this paper, we provide a mathematical model for the electrolocation in weakly electric fishes. We first investigate the forward complex conductivity problem and derive the approx- imate boundary conditions on the skin of the fish. Then we provide a dipole approximation for small targets away from the fish. Based on this approximation, we obtain a non-iterative location search algorithm using multi-frequency measurements. We present numerical experi- ments to illustrate the performance and the stability of the proposed multi-frequency location search algorithm. Finally, in the case of disk- and ellipse-shaped targets, we provide a method to reconstruct separately the conductivity, the permittivity, and the size of the targets from multi-frequency measurements.

Ammari, Habib; Garnier, Josselin

2012-01-01T23:59:59.000Z

277

Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen  

Science Conference Proceedings (OSTI)

The application of electrostatic lenses is demonstrated to give a substantial improvement of the two-dimensional (2D) ion/electron imaging technique. This combination of ion lens optics and 2D detection makes “velocity map imaging” possible

André T. J. B. Eppink; David H. Parker

1997-01-01T23:59:59.000Z

278

THE THERMAL STRUCTURE OF GRAVITATIONALLY DARKENED CLASSICAL Be STAR DISKS  

Science Conference Proceedings (OSTI)

The effect of gravitational darkening on models of the thermal structure of Be star disks is systematically studied for a wide range of Be star spectral types and rotation rates. Gravitational darkening causes a reduction of the stellar effective temperature toward the equator and a redirection of energy toward the poles. It is an important physical effect in these star-disk systems because the photoionizing radiation from the central B star is the main energy source for the disk. We have added gravitational darkening to the BEDISK code to produce circumstellar disk models that include both the variation in the effective temperature with latitude and the non-spherical shape of the star in the calculation of the stellar photoionizing radiation field. The effect of gravitational darkening on global measures of disk temperature is generally significant for rotation rates above 80% of critical rotation. For example, a B0V model rotating at 95% of critical has a density-averaged disk temperature Almost-Equal-To 2500 K cooler than its non-rotating counterpart. However, detailed differences in the temperature structure of disks surrounding rotating and non-rotating stars reveal a complex pattern of heating and cooling. Spherical gravitational darkening, an approximation that ignores the changing shape of the star, gives good results for disk temperatures for rotation rates less than Almost-Equal-To 80% of critical. However for the highest rotation rates, the distortion of the stellar surface caused by rotation becomes important.

McGill, M. A.; Sigut, T. A. A.; Jones, C. E. [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

2011-12-20T23:59:59.000Z

279

Discriminating between a Stochastic Gravitational Wave Background and Instrument Noise  

E-Print Network (OSTI)

The detection of a stochastic background of gravitational waves could significantly impact our understanding of the physical processes that shaped the early Universe. The challenge lies in separating the cosmological signal from other stochastic processes such as instrument noise and astrophysical foregrounds. One approach is to build two or more detectors and cross correlate their output, thereby enhancing the common gravitational wave signal relative to the uncorrelated instrument noise. When only one detector is available, as will likely be the case with the Laser Interferometer Space Antenna (LISA), alternative analysis techniques must be developed. Here we show that models of the noise and signal transfer functions can be used to tease apart the gravitational and instrument noise contributions. We discuss the role of gravitational wave insensitive "null channels" formed from particular combinations of the time delay interferometry, and derive a new combination that maintains this insensitivity for unequal arm length detectors. We show that, in the absence of astrophysical foregrounds, LISA could detect signals with energy densities as low as $\\Omega_{\\rm gw} = 6 \\times 10^{-13}$ with just one month of data. We describe an end-to-end Bayesian analysis pipeline that is able to search for, characterize and assign confidence levels for the detection of a stochastic gravitational wave background, and demonstrate the effectiveness of this approach using simulated data from the third round of Mock LISA Data Challenges.

Matthew R. Adams; Neil J. Cornish

2010-02-05T23:59:59.000Z

280

The Monotonicity of the Gravitational Entropy Scalar within Quiescent Cosmology  

E-Print Network (OSTI)

In this paper we show that Quiescent Cosmology [1, 2, 3] is consistent with Penrose's Weyl Curvature Hypothesis and the notion of gravitational entropy [4]. Gravitational entropy, from a conceptual point of view, acts in an opposite fashion to the more familiar notion of entropy. A closed system of gravitating particles will coalesce whereas a collection of gas particles will tend to diffuse; regarding increasing entropy, these two scenarios are identical. What has been shown previously [2, 3] is that gravitational entropy at the initial singularity predicted by Quiescent Cosmology - the Isotropic Past Singularity (IPS) - tends to zero. The results from this paper show that not only is this the case but that gravitational entropy increases as this singularity evolves. In the first section of this paper we present relevant background information and motivation. In the second section of this paper we present the main results of this paper. Our third section contains a discussion of how this result will inspire future research before we make concluding remarks in our final section.

Philip Threlfall; Susan M. Scott

2012-11-26T23:59:59.000Z

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281

The Effect of Bright Lenses in the Astrometric Measurements of MACHO Proper Motion  

E-Print Network (OSTI)

In current microlensing experiments, the information about the physical parameters of individual lenses are obtained from the Einstein timescales. However, the nature of MACHOs is still very uncertain despite the large number of detected events. This uncertainty is mainly due to the degeneracy of the lens parameters in the measured Einstein timescales. The degeneracy can be lifted in a general fashion if the angular Einstein ring radius $\\theta_{\\rm E}$, and thus the MACHO proper motion, can be measured by conducting accurate astrometric measurements of centroid displacement in the source star image. In this paper, we analyze the influence of bright lenses on the astrometric measurements of the centroid displacement and investigate this effect on the determination of $\\theta_{\\rm E}$. We find that if an event is caused by a bright lens, the centroid displacement is distorted by the flux of the lens and resulting astrometric ellipse becomes rounder and smaller with increasing lens brightness, causing an incorr...

Jeong, Y; Park, S H; Jeong, Youngjin; Han, Cheongho; Park, Sung-Hong

1998-01-01T23:59:59.000Z

282

MHK Technologies/WEGA wave energy gravitational absorber | Open Energy  

Open Energy Info (EERE)

WEGA wave energy gravitational absorber WEGA wave energy gravitational absorber < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage WEGA wave energy gravitational absorber.jpg Technology Profile Primary Organization Sea for Life Technology Type Click here Oscillating Wave Surge Converter Technology Readiness Level Click here TRL 5 6 System Integration and Technology Laboratory Demonstration Technology Description The WEGA device is an articulated suspended body semi submerged attached to a mount structure that oscillates in an elliptical orbit with the passage of the waves The movement of the body drives an hydraulic cylinder which pushes high pressure fluid through an accumulator and an hydraulic motor driving the generator that produces energy The articulated body attaches to the mount structure through a rotary head which allows it to adapt to the direction wave propagation Multiple devices can be placed on a single mount structure according to the size and place of the structure

283

Entropy of singularities in self-gravitating radiation  

E-Print Network (OSTI)

The Bekenstein-Hawking entropy suggests that thermodynamics is an intrinsic ingredient of gravity. Here, we explore the idea that requirements of thermodynamic consistency could determine the gravitational entropy in other set-ups. We implement this idea in a simple model: static, spherically symmetric solutions to Einstein's equations corresponding to self-gravitating radiation. We find that the principle of maximum entropy provides a consistent thermodynamic description of the system, only if the entropy includes a contribution from the spacetime singularities that appear in the solutions of Einstein's equations. The form of the singularity entropy is stringently constrained from consistency requirements, so that the existence of a simple expression satisfying these constraints is highly non-trivial, and suggests of a fundamental origin. We find that the system is characterized by three equilibrium phases, and we conduct a preliminary investigation of the associated phase transitions. These results demonstrate the point that gravitational entities other than horizons are endowed with thermodynamic properties.

Charis Anastopoulos; Ntina Savvidou

2011-03-20T23:59:59.000Z

284

GRAVITATIONAL WAVES OF JET PRECESSION IN GAMMA-RAY BURSTS  

SciTech Connect

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.

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)

2012-06-10T23:59:59.000Z

285

Astrophysically Triggered Searches for Gravitational Waves: Status and Prospects  

E-Print Network (OSTI)

In gravitational-wave detection, special emphasis is put onto searches that focus on cosmic events detected by other types of astrophysical observatories. The astrophysical triggers, e.g. from gamma-ray and X-ray satellites, optical telescopes and neutrino observatories, provide a trigger time for analyzing gravitational wave data coincident with the event. In certain cases the expected frequency range, source energetics, directional and progenitor information is also available. Beyond allowing the recognition of gravitational waveforms with amplitudes closer to the noise floor of the detector, these triggered searches should also lead to rich science results even before the onset of Advanced LIGO. In this paper we provide a broad review of LIGO's astrophysically triggered searches and the sources they target.

Abbott, B; Adhikari, R; Ajith, P; Allen, B; Allen, G; Amin, R; Anderson, S B; Anderson, W G; Arain, M A; Araya, M; Armandula, H; Armor, P; Aso, Y; Aston, S; Aufmuth, P; Aulbert, C; Babak, S; Ballmer, S; Bantilan, H; Barish, B C; Barker, C; Barker, D; Barr, B; Barriga, P; Barton, M A; Bastarrika, M; Bayer, K; Betzwieser, J; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Biswas, R; Black, E; Blackburn, K; Blackburn, L; Blair, D; Bland, B; Bodiya, T P; Bogue, L; Bork, R; Boschi, V; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brinkmann, M; Brooks, A; Brown, D A; Brunet, G; Bullington, A; Buonanno, A; Burmeister, O; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cannizzo, J; Cannon, K; Cao, J; Cardenas, L; Casebolt, T; Castaldi, G; Cepeda, C; Chalkley, E; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Christensen, N; Clark, D; Clark, J; Cokelaer, T; Conte, R; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Cumming, A; Cunningham, L; Cutler, R M; Dalrymple, J; Danzmann, K; Davies, G; De Bra, D; Degallaix, J; Degree, M; Dergachev, V; Desai, S; DeSalvo, R; Dhurandhar, S; Daz, M; Dickson, J; Dietz, A; Donovan, iF; Dooley, K L; Doomes, E E; Drever, R W P; Duke, I; Dumas, J C; Dupuis, R J; Dwyer, J G; Echols, C; Eer, A; Ehrens, P; Espinoza, E; Etzel, T; Evans, T; Fairhurst, S; Fan, Y; Fazi, D; Fehrmann, H; Fejer, M M; Finn, L S; Flasch, K; Fotopoulos, N; Freise, A; Frey, R; Fricke, T; Fritschel, P; Frolov, V V; Fyffe, M; Garofoli, J; Gholami, I; Giaime, J A; Giampanis, S; Giardina, K D; Goda, K; Goetz, E; Goggin, L; González, G; Gossler, S; Gouaty, R; Grant, A; Gras, S; Gray, aC; Gray, M; Greenhalgh, R J S; Gretarsson, A M; Grimaldi, F; Grosso, R; Grote, H; Grünewald, S; Günther, M; Gustafson, E K; Gustafson, R; Hage, B; Hallam, J M; Hammer, D; Hanna, C; Hanson, J; Harms, J; Harry, G; Harstad, E; Hayama, K; Hayler, T; Heefner, J; Heng, I S; Hennessy, M; Heptonstall, A; Hewitson, M; Hild, S; Hirose, E; Hoak, D; Hosken, D; Hough, J; Huttner, S H; Ingram, D; Ito, M; Ivanov, A; Johnson, B; Johnson, W W; Jones, D I; Jones, G; Jones, R; Ju, L; Kalmus, Peter Ignaz Paul; Kalogera, V; Kamat, S; Kanner, J; Kasprzyk, D; Katsavounidis, E; Kawabe, K; Kawamura, S; Kawazoe, F; Kells, W; Keppel, D G; Khalili, F Ya; Khan, R; Khazanov, E; Kim, C; King, P; Kissel, J S; Klimenko, S; Kokeyama, K; Kondrashov, V; Kopparapu, R K; Kozak, D; Kozhevatov, I; Krishnan, B; Kwee, P; Lam, P K; Landry, M; Lang, M M; Lantz, B; Lazzarini, A; Lei, M; Leindecker, N; Leonhardt, V; Leonor, I; Libbrecht, K; Lin, H; Lindquist, P; Lockerbie, N A; Lodhia, D; Lormand, M; Lu, P; Lubinski, M; Lucianetti, A; Luck, H; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Mandic, V; Mrka, S; Mrka, Z; Markosyan, A; Markowitz, J; Maros, aaE; Martin, I; Martin, R M; Marx, J N; Mason, K; Matichard, F; Matone, L; Matzner, R; Mavalvala, N; McCarthy, R; McClelland, D E; McGuire, S C; McHugh, M; McIntyre, G; McIvor, G; McKechan, D; McKenzie, K; Meier, T; Melissinos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C J; Meyers, D; Miller, J; Minelli, J; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Moe, B; Mohanty, S; Moreno, G; Mossavi, K; Mow Lowry, C; Müller, G; Mukherjee, S; Mukhopadhyay, H; Muller-Ebhardt, H; Munch, J; Murray, P; Myers, E; Myers, J; Nash, T; Nelson, J; Newton, G; Nishizawa, A; Numata, K; O'Dell, J; Ogin, G; O'Reilly, B; O'Shaughnessy, R; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pan, Y; Pankow, C; Papa, M A; Parameshwaraiah, V; Patel, P; Pedraza, M; Penn, S; Perreca, A; Petrie, T; Pinto, I M; Pitkin, M; Pletsch, H J; Plissi, M V; Postiglione, F; Principe, M; Prix, R; Quetschke, V; Raab, F; Rabeling, D S; Radkins, H; Rainer, N; Rakhmanov, M; Ramsunder, M; Rehbein, H; Reid, S; Reitze, D H; Riesen, R; Riles, K; Rivera, B; Robertson, N A; Robinson, C; Robinson, E L; Roddy, S; Rodríguez, A; Rogan, A M; Rollins, J; Romano, J D; Romie, J; Route, R; Rowan, S; Rüdiger, A; Ruet, L; Russell, P; Ryan, K; Sakata, S; Samidi, M; Sanchodela Jordana, L; Sandberg, V; Sannibale, V; Saraf, S; Sarin, P; Sathyaprakash, B S; Sato, S; Saulson, P R; Savage, R; Savov, P; Schediwy, S W; Schilling, R; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seifert, F; Sellers, D; Sengupta, A S; Shawhan, P; Shoemaker, D H; Sibley, A; Siemens, X; Sigg, D; Sinha, S; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, N D; Somiya, K; Sorazu, B; Stein, L C; Stochino, A; Stone, R; Strain, K A; Strom, D M; Stuver, A; Summerscales, T Z; Sun, K X; Sung, M; Sutton, P J; Takahashi, H; Tanner, D B; Taylor, R; Taylor, R; Thacker, J; Thorne, K A; Thorne, K S; Thüring, A; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Trias, M; Tyler, W; Ugolini, D; Ulmen, J; Urbanek, K; Vahlbruch, H; Van Den Broeck, C; vander Sluys, M; Vass, S; Vaulin, R; Vecchio, A; Veitch, J; Veitch, P; Villar, A

2008-01-01T23:59:59.000Z

286

Bayesian detection of unmodeled bursts of gravitational waves  

E-Print Network (OSTI)

The data analysis problem of coherently searching for unmodeled gravitational-wave bursts in the data generated by a global network of gravitational-wave observatories has been at the center of research for almost two decades. As data from these detectors is starting to be analyzed, a renewed interest in this problem has been sparked. A Bayesian approach to the problem of coherently searching for gravitational wave bursts with a network of ground-based interferometers is here presented. We demonstrate how to systematically incorporate prior information on the burst signal and its source into the analysis. This information may range from the very minimal, such as best-guess durations, bandwidths, or polarization content, to complete prior knowledge of the signal waveforms and the distribution of sources through spacetime. We show that this comprehensive Bayesian formulation contains several previously proposed detection statistics as special limiting cases, and demonstrate that it outperforms them.

Antony C. Searle; Patrick J. Sutton; Massimo Tinto

2008-09-16T23:59:59.000Z

287

Tail terms in gravitational radiation reaction via effective field theory  

E-Print Network (OSTI)

Gravitational radiation reaction affects the dynamics of gravitationally bound binary systems. Here we focus on the leading "tail" term which modifies binary dynamics at fourth post-Newtonian order, as first computed by Blanchet and Damour. We re-produce this result using effective field theory techniques in the framework of the Lagrangian formalism suitably extended to include dissipation effects. We recover the known logarithmic tail term, consistently with the recent interpretation of the logarithmic tail term in the mass parameter as a renormalization group effect of the Bondi mass of the system.

S. Foffa; R. Sturani

2011-11-23T23:59:59.000Z

288

Gravitational radiation from long gamma-ray bursts  

E-Print Network (OSTI)

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.

Maurice H. P. M. van Putten

2001-02-11T23:59:59.000Z

289

Bayesian estimation of pulsar parameters from gravitational wave data  

E-Print Network (OSTI)

We present a method of searching for, and parameterizing, signals from known radio pulsars in data from interferometric gravitational wave detectors. This method has been applied to data from the LIGO and GEO 600 detectors to set upper limits on the gravitational wave emission from several radio pulsars. Here we discuss the nature of the signal and the performance of the technique on simulated data. We show how to perform a coherent multiple detector analysis and give some insight in the covariance between the signal parameters.

Réjean J. Dupuis; Graham Woan

2005-08-23T23:59:59.000Z

290

The Behavior of Gravitational Modes in Numerical Forecasts with the NCAR Community Climate Model  

Science Conference Proceedings (OSTI)

Characteristics of gravitational-wave noise in noninitialized forecasts were investigated with the NCAR Community Climate Model. Forecasts were begun from FGGE analyses. The behavior of individual, gravitational normal modes was examined. In ...

R. M. Errico; D. L. Williamson

1988-09-01T23:59:59.000Z

291

Effective gravitational wave stress-energy tensor in alternative theories of gravity  

E-Print Network (OSTI)

The inspiral of binary systems in vacuum is controlled by the stress-energy of gravitational radiation and any other propagating degrees of freedom. For gravitational waves, the dominant contribution is characterized by ...

Stein, Leo Chaim

292

The search for gravitational wave bursts in data from the second LIGO science run  

E-Print Network (OSTI)

The network of detectors comprising the Laser Interferometer Gravitational-wave Observatory (LIGO) are among a new generation of detectors that seek to make the first direct observation of gravitational waves. While providing ...

Chatterji, Shourov Keith

2005-01-01T23:59:59.000Z

293

First LIGO search for gravitational wave bursts from cosmic (super)strings  

E-Print Network (OSTI)

We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected ...

Zucker, Michael E.

294

 

NLE Websites -- All DOE Office Websites (Extended Search)

redshift requirements for lens galaxies in galaxy-galaxy redshift requirements for lens galaxies in galaxy-galaxy lensing analysis Reiko Nakajima (UC Berkeley / LBNL) Abstract: Weak gravitational lensing is a valuable probe of galaxy formation and cosmology. However, quantifying its signal to mass requires redshift information of lens and source. In this talk, I will discuss the use of photometric redshifts (photo-z) in weak gravitational lensing, in particular for applications with galaxy-galaxy lensing. We have used the ZEBRA template-based method to estimate the redshifts from SDSS DR8 photometry, for both lens and source catalogs. A heterogeneous set of spectroscopic surveys (zCOSMOS, EGS, VVDS, PRIMUS+DEEP2) were used to calibrate the photo-zs, which were modified to accurately represent the SDSS photometric sample. We find the photo-z errors to be large

295

Gravitational Waves versus Electromagnetic Emission in Gamma-Ray Bursts  

E-Print Network (OSTI)

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 electromagnetic emission in a Gamma-Ray Burst.

Jorge A. Rueda; Remo Ruffini

2012-05-31T23:59:59.000Z

296

Numerical tests of dynamical friction in gravitational inhomogeneous systems  

E-Print Network (OSTI)

In this paper, I test by numerical simulations the results of Del Popolo & Gambera (1998),dealing with the extension of Chandrasekhar and von Neumann's analysis of the statistics of the gravitational field to systems in which particles (e.g., stars, galaxies) are inhomogeneously distributed. The paper is an extension of that of Ahmad & Cohen (1974), in which the authors tested some results of the stochastic theory of dynamical friction developed by Chandrasekhar & von Neumann (1943) in the case of homogeneous gravitational systems. It is also a continuation of the work developed in Del Popolo (1996a,b), which extended the results of Ahmad & Cohen (1973), (dealing with the study of the probability distribution of the stochastic force in homogeneous gravitational systems) to inhomogeneous gravitational systems. Similarly to what was done by Ahmad & Cohen (1974) in the case of homogeneous systems, I test, by means of the evolution of an inhomogeneous system of particles, that the theoretical rate of force fluctuation d F/dt describes correctly the experimental one, I find that the stochastic force distribution obtained for the evolved system is in good agreement with the Del Popolo & Gambera (1998) theory. Moreover, in an inhomogeneous background the friction force is actually enhanced relative to the homogeneous case.

A. Del Popolo

2003-05-05T23:59:59.000Z

297

The extensions of gravitational soliton solutions with real poles  

E-Print Network (OSTI)

We analyse vacuum gravitational "soliton" solutions with real poles in the cosmological context. It is well known that these solutions contain singularities on certain null hypersurfaces. Using a Kasner seed solution, we demonstrate that these may contain thin sheets of null matter or may be simple coordinate singularities, and we describe a number of possible extensions through them.

J. B. Griffiths; S. Micciche

1998-11-02T23:59:59.000Z

298

Inflationary Behaviour in Axial-symmetric Gravitational Collapse  

E-Print Network (OSTI)

We show that the interior of a charged, spinning black hole formed from a general axially symmetric gravitational collapse is unstable to inflation of both its mass and angular momentum parameters. Although our results are formulated in the context of $(2+1)$-dimensional black holes, we argue that they are applicable to $(3+1)$ dimensions.

J. S. F. Chan; R. B. Mann

1994-11-25T23:59:59.000Z

299

Analysis of gravitational wave signals on heterogeneous architectures  

Science Conference Proceedings (OSTI)

Heterogeneous architectures and programming techniques will be very important in the development of exascale HPC applications. Adapting heterogeneous programming techniques to scientific programming is not always straightforward. Here we present an in-depth ... Keywords: gravitational waves, hybrid computing, parallel computations

Maciej Cytowski

2010-06-01T23:59:59.000Z

300

Gravitational Self-Energy and Black Holes in Newtonian Physics  

E-Print Network (OSTI)

A definition of a Newtonian black hole is possible which incorporates the mass-energy equivalence from special relativity. However, exploiting a double spherical shell model, it will be shown that the ensuing gravitational self-energy and mass renormalization prevent the formation of such an object.

G. Dillon

2013-02-15T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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301

Gravitational Self-Energy and Black Holes in Newtonian Physics  

E-Print Network (OSTI)

A definition of a Newtonian black hole is possible which incorporates the mass-energy equivalence from special relativity. However, exploiting a double spherical shell model, it will be shown that the ensuing gravitational self-energy and mass renormalization prevent the formation of such an object.

Dillon, G

2013-01-01T23:59:59.000Z

302

Phase estimation with weak measurement using a white light source  

E-Print Network (OSTI)

We report results of a high precision phase estimation based on a weak measurements scheme using commercial light-emitting diode. The method is based on a measurement of the imaginary part of the weak value of a polarization operator. The imaginary part of the weak value appeared due to the measurement interaction itself. The sensitivity of our method is equivalent to resolving light pulses of order of attosecond and it is robust against chromatic dispersion.

Xiao-Ye Xu; Yaron Kedem; Kai Sun; Lev Vaidman; Chuan-Feng Li; Guang-Can Guo

2013-06-20T23:59:59.000Z

303

Weak nuclear forces cause the strong nuclear force  

E-Print Network (OSTI)

We determine the strength of the weak nuclear force which holds the lattices of the elementary particles together. We also determine the strength of the strong nuclear force which emanates from the sides of the nuclear lattices. The strong force is the sum of the unsaturated weak forces at the surface of the nuclear lattices. The strong force is then about ten to the power of 6 times stronger than the weak force between two lattice points.

E. L. Koschmieder

2007-12-11T23:59:59.000Z

304

Interaction between Lattice Dislocation and Weak Interface in ...  

Science Conference Proceedings (OSTI)

We studied the interaction between lattice dislocations and weak interfaces in anisotropic bi-layer composites by using the Green's function method.

305

ElectroWeak theory after the first LHC phase  

E-Print Network (OSTI)

I summarize the status of the ElectroWeak Interactions after the first phase of the Large Hadron Collider and I give an outlook on its possible developments.

Riccardo Barbieri

2013-09-13T23:59:59.000Z

306

ElectroWeak theory after the first LHC phase  

E-Print Network (OSTI)

I summarize the status of the ElectroWeak Interactions after the first phase of the Large Hadron Collider and I give an outlook on its possible developments.

Barbieri, Riccardo

2013-01-01T23:59:59.000Z

307

Gravitational Quenching in Massive Galaxies and Clusters by Clumpy Accretion  

E-Print Network (OSTI)

We consider a simple gravitational-heating mechanism for the long-term quenching of cooling flows and star formation in massive dark-matter haloes hosting ellipticals and clusters. The virial shock heating in haloes >10^12 Mo triggers quenching in 10^12-13 Mo haloes (Birnboim, Dekel & Neistein 2007). We show that the long-term quenching in haloes >Mmin~7x10^12 Mo could be due to the gravitational energy of cosmological accretion delivered to the inner-halo hot gas by cold flows via ram-pressure drag and local shocks. Mmin is obtained by comparing the gravitational power of infall into the potential well with the overall radiative cooling rate. The heating wins if the gas inner density cusp is not steeper than r^-0.5 and if the masses in the cold and hot phases are comparable. The effect is stronger at higher redshifts, making the maintenance easier also at later times. Clumps >10^5 Mo penetrate to the inner halo with sufficient kinetic energy before they disintegrate, but they have to be Alternatively, such clumps may be embedded in dark-matter subhaloes if the ionizing flux is ineffective, but they separate from their subhaloes by ram pressure before entering the inner halo. Heating by dynamical friction becomes dominant for massive satellites, which can contribute up to one third of the total gravitational heating. We conclude that gravitational heating by cosmological accretion is a viable alternative to AGN feedback as a long-term quenching mechanism.

Avishai Dekel; Yuval Birnboim

2007-07-09T23:59:59.000Z

308

LISA-2020: An Intermediate Scale Space Gravitational Wave Observatory for This Decade  

E-Print Network (OSTI)

Over the last three decades, an exceptionally good science case has been made for pursuing gravitational wave (GW) astronomy. This has engendered a worldwide effort to detect the extremely weak signals generated by expected sources. With the next round of upgrades the ground based instruments are likely to make the first detections of the sources, and a new era of astronomy will begin, possibly as early as 2017. Inconveniently, due to seismic noise and baseline length issues, the low frequency (2030 now seems very unlikely. This paper examines the case for a scaled down mission that is comparable in cost and duration to medium scale astrophysics missions such as the 1978 ($630M) Einstein (HEAO 2) x-ray Observatory2, the 1989 ($680M) COBE Cosmic Background Explorer3, and the 1999 ($420M) FUSE Far Ultraviolet Spectroscopic Explorer4. We find that a mission of this class is possible if the measurement requirements are somewhat relaxed and a baseline smaller than LISA is used. It appears that such a mission could be launched by 2020 using a conventional program development plan, possibly including international collaboration. It would enable the timely development of this game-changing field of astrophysics, complementing the expected ground results with observations of massive black hole collisions. It would also serve as a stepping stone to LISA, greatly reducing the risk profile of that mission.

S. Buchman; J. A. Lipa; R. L. Byer; D. DeBra; K. Balakrishnan; G. Dufresne Cutler; A. Al-Fauwaz; E. Hultgren; A. K. Al-Jadaan; S. Saraf; S. Tan; S. Al-Thubiti; A. Zoellner

2013-02-10T23:59:59.000Z

309

End-point of the rp process and periodic gravitational wave emission  

E-Print Network (OSTI)

The general end-point of the rp process in rapidly accreting neutron stars is believed to be a surface distribution of matter whose nuclear composition may depend on position. Its evolution during compression beyond the neutron-drip threshold density is determined by the presence of nuclear formation enthalpy minima at the proton closed shells. At threshold, a sequence of weak interactions with capture or emission of neutron pairs rapidly transform nuclei to the most accessible proton closed shell. Therefore, angular asymmetries in nuclear composition present in accreted matter at neutron drip are preserved during further compression to higher densities provided transition rates between closed shells are negligible. Although it has been confirmed that this condition is satisfied for predicted internal temperatures and for the formation enthalpy distribution used in this work, it would not be so if the true enthalpy differences between maxima and minima in the distribution were a factor of two smaller. For this reason, it does not appear possible to assert with any confidence that position-dependent surface composition can lead to significant angle-dependence of the equation of state and to potentially observable gravitational radiation. The effect of non-radial internal temperature gradients on angle-dependency of the equation of state is also not quantifiable.

P. B. Jones

2005-02-09T23:59:59.000Z

310

Higgs Production via Gluon-Induced Weak Boson Fusion  

E-Print Network (OSTI)

We present a calculation that allows for an estimation of the NNLO contributions to the Higgs production in the weak boson fusion channel. A possible deterioration of this important channel for the Higgs discoveries at the LHC can be ruled out by this calculation due to the small remaining cross section after the weak boson cuts.

Jens Vollinga

2008-09-22T23:59:59.000Z

311

Constraints on Dark Energy Models from Weak Gravity Conjecture  

E-Print Network (OSTI)

We study the constraints on the dark energy model with constant equation of state parameter $w=p/\\rho$ and the holographic dark energy model by using the weak gravity conjecture. The combination of weak gravity conjecture and the observational data gives $wenergy model realized by a scalar field is in swampland.

Chen, Ximing; Gong, Yungui

2008-01-01T23:59:59.000Z

312

Constraints on Dark Energy Models from Weak Gravity Conjecture  

E-Print Network (OSTI)

We study the constraints on the dark energy model with constant equation of state parameter $w=p/\\rho$ and the holographic dark energy model by using the weak gravity conjecture. The combination of weak gravity conjecture and the observational data gives $wenergy model realized by a scalar field is in swampland.

Ximing Chen; Jie Liu; Yungui Gong

2008-06-15T23:59:59.000Z

313

The Perturbative Onset of Multiparticle Production in Weak Interactions  

E-Print Network (OSTI)

We use perturbation theory to estimate the energy scale beyond which multiparticle final states become a dominant feature of high energy weak interactions. Using estimates from a weak parton model and comparing two, three and four body final states we deduce that multiparticle states become important at energy scales in the range 10**7 - 10**9 GeV.

D. A. Morris; R. Rosenfeld

1992-10-19T23:59:59.000Z

314

Processing on Information Fusion of Weak Electrical Signals in Plants  

Science Conference Proceedings (OSTI)

Information transmission of weak electrical signals in Bellis perennis was inosculated by a touching test system of self-made double shields with platinum sensors. Tested data of electrical signals denoised by the wavelet soft threshold and using Gaussian ... Keywords: intelligent control, information fusion, RBF neural networks, wavelet soft threshold denoising, weak electrical signal, Bellis perennis

Lanzhou Wang; Jinli Ding

2010-06-01T23:59:59.000Z

315

Charge Management for Gravitational Wave Observatories using UV LEDs  

E-Print Network (OSTI)

Accumulation of electrical charge on the end mirrors of gravitational wave observatories, such as the space-based LISA mission and ground-based LIGO detectors, can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable Au-coated Cu plate brought near a Au-coated Si plate pendulum suspended from a non-conducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging of the pendulum with equivalent charging rates of $\\sim

Pollack, S E; Schlamminger, S; Hagedorn, C A; Gundlach, J H

2009-01-01T23:59:59.000Z

316

Improved time-domain accuracy standards for model gravitational waveforms  

Science Conference Proceedings (OSTI)

Model gravitational waveforms must be accurate enough to be useful for detection of signals and measurement of their parameters, so appropriate accuracy standards are needed. Yet these standards should not be unnecessarily restrictive, making them impractical for the numerical and analytical modelers to meet. The work of Lindblom, Owen, and Brown [Phys. Rev. D 78, 124020 (2008)] is extended by deriving new waveform accuracy standards which are significantly less restrictive while still ensuring the quality needed for gravitational-wave data analysis. These new standards are formulated as bounds on certain norms of the time-domain waveform errors, which makes it possible to enforce them in situations where frequency-domain errors may be difficult or impossible to estimate reliably. These standards are less restrictive by about a factor of 20 than the previously published time-domain standards for detection, and up to a factor of 60 for measurement. These new standards should therefore be much easier to use effectively.

Lindblom, Lee [Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125 (United States); Baker, John G. [Gravitational Astrophysics Laboratory, NASA/GSFC, Greenbelt, Maryland 20771 (United States); Owen, Benjamin J. [Institute for Gravitation and the Cosmos, Center for Gravitational Wave Physics, Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2010-10-15T23:59:59.000Z

317

Chemical potential as a source of stability for gravitating Skyrmions  

E-Print Network (OSTI)

A discussion of the stability of self gravitating Skyrmions, with a large winding number N, in a Schwarzschild type of metric, is presented for the case where an isospin chemical potential is introduced. It turns out that the chemical potential stabilizes the behavior of the Skyrmion discussed previously in the literature. This analysis is carried on in the framework of a variational approach using different ansaetze for the radial profile of the Skyrmion. We found a divergent behavior for the size of the Skyrmion, associated to a certain critical value $\\mu_c$ of the chemical potential. At this point, the mass of the Skyrmion vanishes. $\\mu_c$ is essentialy independent of gravitating effects. The stability of a large N skyrmion against decays into single particles is also discussed.

M. Loewe; S. Mendizabal; J. C. Rojas

2006-08-10T23:59:59.000Z

318

Practical speed meter designs for QND gravitational-wave interferometers  

E-Print Network (OSTI)

In the quest to develop viable designs for third-generation optical interferometric gravitational-wave detectors (e.g., LIGO-III and EURO), one strategy is to monitor the relative momentum or speed of the test-mass mirrors, rather than monitoring their relative position. A previous paper analyzed a straightforward but impractical design for a {\\it speed-meter interferometer} that accomplishes this. This paper describes some practical variants of speed-meter interferometers. Like the original interferometric speed meter, these designs {\\it in principle} can beat the gravitational-wave standard quantum limit (SQL) by an arbitrarily large amount, over an arbitrarily wide range of frequencies. These variants essentially consist of a Michelson interferometer plus an extra "sloshing" cavity that sends the signal back into the interferometer with opposite phase shift, thereby cancelling the position information and leaving a net phase shift proportional to the relative velocity. {\\it In practice}, the sensitivity of...

Purdue, P; Purdue, Patricia; Chen, Yanbei

2002-01-01T23:59:59.000Z

319

Quantum Limits of Interferometer Topologies for Gravitational Radiation Detection  

E-Print Network (OSTI)

In order to expand the astrophysical reach of gravitational wave detectors, several interferometer topologies have been proposed to evade the thermodynamic and quantum mechanical limits in future detectors. In this work, we make a systematic comparison among them by considering their sensitivities and complexities. We numerically optimize their sensitivities by introducing a cost function that tries to maximize the broadband improvement over the sensitivity of current detectors. We find that frequency-dependent squeezed-light injection with a hundred-meter scale filter cavity yields a good broadband sensitivity, with low complexity, and good robustness against optical loss. This study gives us a guideline for the near-term experimental research programs in enhancing the performance of future gravitational-wave detectors.

Haixing Miao; Huan Yang; Rana X Adhikari; Yanbei Chen

2013-05-17T23:59:59.000Z

320

First upper limits from LIGO on gravitational wave bursts  

E-Print Network (OSTI)

We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h_{rss}; typical sensitivities lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.

Abbott, B; Adhikari, R; Ageev, A N; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S V; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, D; Barker-Patton, C; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff,S J; Betzwieser, J; Bhawal, B; Bilenko, I A; Billingsley, G; Black, E; Blackburn, K; Bland-Weaver, B; Bochner, B; Bogue, L; Bork, R G; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brown, D A; Brozek, S; Bullington, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Colacino, C N; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Davies, R; Daw, E; De Bra, D; Delker, T; DeSalvo, R; Dhurandhar, S V; Ding, H; Drever, R W P; Dupuis, R J; Ebeling, C; Edlund, J; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fallnich, C; Farnham, D; Fejer, M M; Fine, M; Finn, L S; Flanagan, E; Freise, A; Frey, R; Fritschel, P; Frolov, V; Fyffe, M; Ganezer, K S; Giaime, J A; Gillespie, A; Goda, K; González, G; Goler, S; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Günther, M; Gustafson, E; Gustafson, R; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ingley, R; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, W W; Johnston, W; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Kloevekorn, P; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonhardt, V; Leonor, I; Libbrecht, K; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Lück, H B; Lyons, T T; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K O; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNamara, P; Mendell, G; Meshkov, S; Messenger, C; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Mours, B; Müller, G; Mukherjee, S; Myers, J; Nagano, S; Nash, T; Naundorf, H; Nayak, R; Newton, G; Nocera, F; Nutzman, P; Olson, T; O'Reilly, B; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Papa, M A; Parameswariah, C; Parameshwaraiah, V; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Pratt, M; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Redding, D; Regehr, M W; Regimbau, T; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Rüdiger, A; Russell, P; Ryan, K; Salzman, I; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schofield, R; Schrempel, M; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seel, S; Sengupta, A S; Shapiro, C A; Shawhan, P S; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Skeldon, K D; Smith, J R; Smith, M; Smith, M R; Sneddon, P; Spero, R; Stapfer, G; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Tokmakov, K V; Torres, C; Torrie, C; Traeger, S; Traylor, G; Tyler, W; Ugolini, D W; Vallisneri, M; Van, M; Putten; Vass, S; Vecchio, A; Vorvick, C; Vyachanin, S P; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Yakushin, I; Yamamoto, H; Yoshida, S; Zawischa, I; Zhang, L; Zotov, N P; Zucker, M; Zweizig, J

2004-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Boosted static multipole particles as sources of impulsive gravitational waves  

E-Print Network (OSTI)

It is shown that the known solutions for nonexpanding impulsive gravitational waves generated by null particles of arbitrary multipole structure can be obtained by boosting the Weyl solutions describing static sources with arbitrary multipole moments, at least in a Minkowski background. We also discuss the possibility of boosting static sources in (anti-) de Sitter backgrounds, for which exact solutions are not known, to obtain the known solutions for null multipole particles in these backgrounds.

J. Podolsky; J. B. Griffiths

1998-09-01T23:59:59.000Z

322

Shear-free gravitational collapse is strongly censored  

E-Print Network (OSTI)

We consider spherically symmetric spacetimes with matter whose timelike flow is assumed to be shear-free. A number of results on the formation and visibility of spacetime singularities is proven, with the main one being that shear-free collapse cannot admit locally naked singularities (which implies absence of globally naked singularities). We conjecture that shear is a necessary condition for the occurrence of locally naked singularities in generic gravitational collapse.

Sergio M. C. V. Goncalves

2003-12-30T23:59:59.000Z

323

Probing the Brans-Dicke Gravitational Field by Cerenkov Radiation  

E-Print Network (OSTI)

The possibility that a charged particle propagating in a gravitational field described by Brans-Dicke theory of gravity could emit Cerenkov radiation is explored. This process is kinematically allowed depending on parameters occurring in the theory. The Cerenkov effect disappears as the BD parameter ? ? ?, i.e. in the limit in which the Einstein theory is recovered, giving a signature to probe the validity of the Brans-Dicke theory.

G. Lambiase A B

2001-01-01T23:59:59.000Z

324

Probing the Brans-Dicke Gravitational Field by Cerenkov Radiation  

E-Print Network (OSTI)

The possibility that a charged particle propagating in a gravitational field described by Brans-Dicke theory of gravity could emit Cerenkov radiation is explored. This process is kinematically allowed depending on parameters occurring in the theory. The Cerenkov effect disappears as the BD parameter omega tends to inftinity, i.e. in the limit in which the Einstein theory is recovered, giving a signature to probe the validity of the Brans-Dicke theory.

G. Lambiase

2001-10-25T23:59:59.000Z

325

A study of the gravitational wave form from pulsars II  

E-Print Network (OSTI)

We present analytical and numerical studies of the Fourier transform (FT) of the gravitational wave (GW) signal from a pulsar, taking into account the rotation and orbital motion of the Earth. We also briefly discuss the Zak-Gelfand Integral Transform. The Zak-Gelfand Integral Transform that arises in our analytic approach has also been useful for Schrodinger operators in periodic potentials in condensed matter physics (Bloch wave functions).

S. R. Valluri; J. J. Drozd; F. A. Chishtie; R. G. Biggs; M. Davison; S. V. Dhurandhar; B. S. Sathyaprakash

2001-10-29T23:59:59.000Z

326

Optics Elements for Modeling Electrostatic Lenses and Accelerator Components: III. Electrostatic Deflectors  

DOE Green Energy (OSTI)

Ion-beam optics models for simulating electrostatic prisms (deflectors) of different geometries have been developed for the computer code TRACE 3-D. TRACE 3-D is an envelope (matrix) code, which includes a linear space charge model, that was originally developed to model bunched beams in magnetic transport systems and radiofrequency (RF) accelerators. Several new optical models for a number of electrostatic lenses and accelerator columns have been developed recently that allow the code to be used for modeling beamlines and accelerators with electrostatic components. The new models include a number of options for: (1) Einzel lenses, (2) accelerator columns, (3) electrostatic prisms, and (4) electrostatic quadrupoles. A prescription for setting up the initial beam appropriate to modeling 2-D (continuous) beams has also been developed. The models for electrostatic prisms are described in this paper. The electrostatic prism model options allow the modeling of cylindrical, spherical, and toroidal electrostatic deflectors. The application of these models in the development of ion-beam transport systems is illustrated through the modeling of a spherical electrostatic analyzer as a component of the new low energy beamline at CAMS.

Brown, T.A.; Gillespie, G.H.

1999-10-21T23:59:59.000Z

327

Universality of the subsolar mass distribution from critical gravitational collapse  

E-Print Network (OSTI)

Self-similarity induced by critical gravitational collapse is used as a paradigm to probe the mass distribution of subsolar objects. At large mass (solar mass and above) there is widespread agreement as to both the form and parameter values arising in the mass distribution of stellar objects. At subsolar mass there is still considerable disagreement as to the qualitative form of the mass distribution, let alone the specific parameter values characterizing that distribution. For the first time, the paradigm of critical gravitational collapse is applied to several concrete astrophysical scenarios to derive robust qualitative features of the subsolar mass distribution. We further contrast these theoretically derived ideas with the observational situation. In particular, we demonstrate that at very low mass the distribution is given by a power law, with an exponent opposite in sign to that observed in the high-mass regime. The value of this low-mass exponent is in principle calculable via dynamical systems theory applied to gravitational collapse. Qualitative agreement between theory, numerical experiments, and observational data is good, though quantitative issues remain troublesome.

Matt Visser; Nicolas Yunes

2004-04-21T23:59:59.000Z

328

Circular, elliptic and oval billiards in a gravitational field  

E-Print Network (OSTI)

We consider classical dynamical properties of a particle in a constant gravitational force and making specular reflections with circular, elliptic or oval boundaries. The model and collision map are described and a detailed study of the energy regimes is made. The linear stability of fixed points is studied, yielding exact analytical expressions for parameter values at which a period-doubling bifurcation occurs. The dynamics is apparently ergodic at certain energies in all three models, in contrast to the regularity of the circular and elliptic billiard dynamics in the field-free case. This finding is confirmed using a sensitive test involving Lyapunov weighted dynamics. In the last part of the paper a time dependence is introduced in the billiard boundary, where it is shown that for the circular billiard the average velocity saturates for zero gravitational force but in the presence of gravitational it increases with a very slow growth rate, which may be explained using Arnold diffusion. For the oval billiard, where chaos is present in the static case, the particle has an unlimited velocity growth with an exponent of approximately 1/6.

D. R. da Costa; C. P. Dettmann; E. D. Leonel

2013-08-01T23:59:59.000Z

329

A single-spin precessing gravitational wave in closed form  

E-Print Network (OSTI)

In coming years, gravitational wave detectors should find black hole-neutron star binaries, potentially coincident with astronomical phenomena like short GRBs. These binaries are expected to precess. Gravitational wave science requires a tractable model for precessing binaries, to disentangle precession physics from other phenomena like modified strong field gravity, tidal deformability, or Hubble flow; and to measure compact object masses, spins, and alignments. Moreover, current searches for gravitational waves from compact binaries use templates where the binary does not precess and are ill-suited for detection of generic precessing sources. In this paper we provide a closed-form representation of the single-spin precessing waveform in the frequency domain by reorganizing the signal as a sum over harmonics, each of which resembles a nonprecessing waveform. This form enables simple analytic calculations (e.g., a Fisher matrix) with easily-interpreted results. We have verified that for generic BH-NS binaries, our model agress with the time-domain waveform to 2\\%. Straightforward extensions of the derivations outlined here [and provided in full online] allow higher accuracy and error estimates.

A. Lundgren; R. O'Shaughnessy

2013-04-11T23:59:59.000Z

330

DARK MATTER AS AN ACTIVE GRAVITATIONAL AGENT IN CLOUD COMPLEXES  

SciTech Connect

We study the effect that the dark matter background (DMB) has on the gravitational energy content and, in general, on the star formation efficiency (SFE) of a molecular cloud (MC). We first analyze the effect that a dark matter halo, described by the Navarro-Frenk-White density profile, has on the energy budget of a spherical, homogeneous cloud located at different distances from the halo center. We found that MCs located in the innermost regions of a massive galaxy can feel a contraction force greater than their self-gravity due to the incorporation of the potential of the galaxy's dark matter halo. We also calculated analytically the gravitational perturbation that an MC produces over a uniform DMB (uniform at the scales of an MC) and how this perturbation will affect the evolution of the MC itself. The study shows that the star formation in an MC will be considerably enhanced if the cloud is located in a dense and low velocity dark matter environment. We confirm our results by measuring the SFE in numerical simulations of the formation and evolution of MCs within different DMBs. Our study indicates that there are situations where the dark matter's gravitational contribution to the evolution of the MCs should not be neglected.

Suarez-Madrigal, Andres; Ballesteros-Paredes, Javier; Colin, Pedro; D'Alessio, Paola, E-mail: a.suarez@crya.unam.mx [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 72-3 (Xangari), Morelia, Michocan, Mexico C.P. 58089 (Mexico)

2012-04-01T23:59:59.000Z

331

Theory of superconductivity of gravitation and the dark matter enigma  

E-Print Network (OSTI)

In this article, the question of the nature of cold dark matter is approached from a new angle. By invoking the Cauchy problem of relativity it is shown how, under very precise astrophysical conditions, the Einstein general theory of relativity is formally equivalent to the Ginzburg-Landau theory of superconductivity. This fact lead us to suspect that the superconductivity of gravitation ought to be a real physical process occurring in the outskirts of galaxies. It is found that quantum mechanically gravity can achieve a type-II superconductor state characterised by the Gizburg-Landau parameter $\\kappa=1.5$, and it is suggested that a probability flux of Cooper pairs (quantum gravitational geons charged with vacuum energy) are directly responsible for the flatness exhibited by the rotation curves in spiral galaxies, as well as the exotic behaviour observed in galactic cluster collisions. If this hypothesis proves correct, the whole phenomenon of dark matter may count, after all, as another triumph for Einstein's theory of gravity. The tension between gravitation and quantum mechanics is explored further by a subtle consideration of the Hamilton-Jacobi theory of the York-time action, providing additional motivation for the above line of reasoning. In particular, Penrose's estimate for the rate of collapse of the wavefunction is recovered, and connected to the instability of Misner space.

Wenceslao Santiago-Germán

2011-12-06T23:59:59.000Z

332

Microoptic lenses  

DOE Patents (OSTI)

The present invention provides several novel diffraction limited microlens configurations which are especially valuable for use in conjunction with laser diodes, and optical fibers. Collimators, circularizers and focusers (couplers) are provided.

Snyder, J.J.

1993-01-19T23:59:59.000Z

333

T-705: Linux Kernel Weakness in Sequence Number Generation Facilitates  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

05: Linux Kernel Weakness in Sequence Number Generation 05: Linux Kernel Weakness in Sequence Number Generation Facilitates Packet Injection Attacks T-705: Linux Kernel Weakness in Sequence Number Generation Facilitates Packet Injection Attacks August 30, 2011 - 3:46am Addthis PROBLEM: A remote user can conduct packet injection attacks. PLATFORM: Linux Kernel ABSTRACT: Linux Kernel Weakness in Sequence Number Generation Facilitates Packet Injection Attacks. reference LINKS: SecurityTracker Alert ID: 1025977 CVE-2011-3188 (under review) The Linux Kernel Archives IMPACT ASSESSMENT: Medium Discussion: A vulnerability was reported in the Linux Kernel. A remote user can conduct packet injection attacks. The kernel's sequence number generation function uses partial MD4 with 24-bits unguessable. A remote user may be able to brute-force guess a valid sequence number to inject a packet into a

334

Violation of the Weak Equivalence Principle in Bekenstein's theory  

E-Print Network (OSTI)

Bekenstein has shown that violation of Weak Equivalence Principle is strongly supressed in his model of charge variation. In this paper, it is shown that nuclear magnetic energy is large enough to produce observable effects in Eotvos experiments.

L. Kraiselburd; H. Vucetich

2009-02-24T23:59:59.000Z

335

Multiscale Large Eddy States in Weakly Stratified Planetary Boundary Layers  

Science Conference Proceedings (OSTI)

We first discuss observations of two classes of two-dimensional large eddy states in weakly stratified atmospheric boundary layers. One class is characterized by large eddies with a single horizontal scale. The other contains multiscale large ...

Pierre D. Mourad; Robert A. Brown

1990-02-01T23:59:59.000Z

336

T-728: Apache Tomcat HTTP DIGEST Authentication Weaknesses Let...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

not checked realm values were not checked the server secret was hard-coded to a known string The result of these weaknesses is that DIGEST authentication was only as secure as...

337

DISCIPLE-1: interactive apprentice system in weak theory fields  

Science Conference Proceedings (OSTI)

The paper presents an interactive approach to learning apprentice systems for weak theory domains. The approach consists of a combination of teaming by analogy and learning by generalizing instances. One main point of this approach is that it uses the ...

Yves Kodratoff; Gheorghe Tecuci

1987-08-01T23:59:59.000Z

338

Corbino-geometry Josephson weak links in thin superconducting films  

Science Conference Proceedings (OSTI)

I consider a Corbino-geometry superconducting-normal-superconducting Josephson weak link in a thin superconducting film, in which current enters at the origin, flows outward, passes through an annular Josephson weak link, and leaves radially. In contrast to sandwich-type annular Josephson junctions, in which the gauge-invariant phase difference obeys the sine-Gordon equation, here the gauge-invariant phase difference obeys an integral equation. I present exact solutions for the gauge-invariant phase difference across the weak link when it contains an integral number N of Josephson vortices and the current is zero. I then study the dynamics when a current is applied, and I derive the effective resistance and the viscous drag coefficient; I compare these results with those in sandwich-type junctions. I also calculate the critical current when there is no Josephson vortex in the weak link but there is a Pearl vortex nearby.

Clem, John R.

2010-11-29T23:59:59.000Z

339

Boils and Turbulence in a Weakly Stratified Shallow Tidal Sea  

Science Conference Proceedings (OSTI)

Measurements of turbulence are made in a weakly but variably stratified region of tidal straining in the eastern Irish Sea using turbulence sensors profiling vertically through the water column on the Fast Light Yo-yo (FLY) profiler and ...

S. A. Thorpe; J. A. M. Green; J. H. Simpson; T. R. Osborn; W. A. M. Nimmo Smith

2008-08-01T23:59:59.000Z

340

Nuclear Constraints on the Weak Nucleon-Nucleon Interaction  

E-Print Network (OSTI)

I discuss the current status of efforts to constrain the strangeness-conserving weak hadronic interaction, which can be isolated in nuclear systems because of the associated parity violation.

W. C. Haxton

2008-02-21T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Weak and strong regimes of incompressible magnetohydrodynamic turbulence  

Science Conference Proceedings (OSTI)

It is shown that in the framework of the weak turbulence theory, the autocorrelation and cascade time scales are always of the same order of magnitude. This means that, contrary to the general belief, any model of turbulence that implies a large number of collisions among wave packets for an efficient energy cascade (such as the Iroshnikov-Kraichnan model) is not compatible with the weak turbulence theory.

Gogoberidze, G. [Centre for Plasma Astrophysics, K. U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Georgian National Astrophysical Observatory, 2a Kazbegi Ave., 0160 Tbilisi, Georgia (United States); Mahajan, S. M. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Poedts, S. [Centre for Plasma Astrophysics, K. U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium)

2009-07-15T23:59:59.000Z

342

Weak rigidity in almost-thermodynamic material schemes  

SciTech Connect

To avoid the restrictions that the Born rigidity supposes for the motions in relativity, the definition of a weakly rigid almost-thermodynamic material scheme is proposed. From it the relativistic incompressibility condition given by Ferrando and Olivert is obtained. Moreover, it is proved that, for the weakly rigid irrotational and geodesic almost-thermodynamic material schemes, the scalar curvature of the Landau manifolds is constant along the streamlines.

del Olmo, V.; Olivert, J.

1985-06-01T23:59:59.000Z

343

Weak coupling limits in a stochastic model of heat conduction  

E-Print Network (OSTI)

We study the Brownian momentum process, a model of heat conduction, weakly coupled to heat baths. In two different settings of weak coupling to the heat baths, we study the non-equilibrium steady state and its proximity to the local equilibrium measure in terms of the strength of coupling. For three and four site systems, we obtain the two-point correlation function and show it is generically not multilinear.

Redig, Frank

2011-01-01T23:59:59.000Z

344

Beating the spin-down limit on gravitational wave emission from the Crab pulsar  

E-Print Network (OSTI)

We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first nine months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the energetics of the nebula. In the second we allow for a small mismatch between the gravitational and radio signal frequencies and interpret our results in the context of two possible gravitational wave emission mechanisms.

The LIGO Scientific Collaboration; B. Abbott; R. Abbott; R. Adhikari; P. Ajith; B. Allen; G. Allen; R. Amin; S. B. Anderson; W. G. Anderson; M. A. Arain; M. Araya; H. Armandula; P. Armor; Y. Aso; S. Aston; P. Aufmuth; C. Aulbert; S. Babak; S. Ballmer; H. Bantilan; B. C. Barish; C. Barker; D. Barker; B. Barr; P. Barriga; M. A. Barton; M. Bastarrika; K. Bayer; J. Betzwieser; P. T. Beyersdorf; I. A. Bilenko; G. Billingsley; R. Biswas; E. Black; K. Blackburn; L. Blackburn; D. Blair; B. Bland; T. P. Bodiya; L. Bogue; R. Bork; V. Boschi; S. Bose; P. R. Brady; V. B. Braginsky; J. E. Brau; M. Brinkmann; A. Brooks; D. A. Brown; G. Brunet; A. Bullington; A. Buonanno; O. Burmeister; R. L. Byer; L. Cadonati; G. Cagnoli; J. B. Camp; J. Cannizzo; K. Cannon; J. Cao; L. Cardenas; T. Casebolt; G. Castaldi; C. Cepeda; E. Chalkley; P. Charlton; S. Chatterji; S. Chelkowski; Y. Chen; N. Christensen; D. Clark; J. Clark; T. Cokelaer; R. Conte; D. Cook; T. Corbitt; D. Coyne; J. D. E. Creighton; A. Cumming; L. Cunningham; R. M. Cutler; J. Dalrymple; K. Danzmann; G. Davies; D. DeBra; J. Degallaix; M. Degree; V. Dergachev; S. Desai; R. DeSalvo; S. Dhurandhar; M. Díaz; J. Dickson; A. Dietz; F. Donovan; K. L. Dooley; E. E. Doomes; R. W. P. Drever; I. Duke; J. -C. Dumas; R. J. Dupuis; J. G. Dwyer; C. Echols; A. Effler; P. Ehrens; E. Espinoza; T. Etzel; T. Evans; S. Fairhurst; Y. Fan; D. Fazi; H. Fehrmann; M. M. Fejer; L. S. Finn; K. Flasch; N. Fotopoulos; A. Freise; R. Frey; T. Fricke; P. Fritschel; V. V. Frolov; M. Fyffe; J. Garofoli; I. Gholami; J. A. Giaime; S. Giampanis; K. D. Giardina; K. Goda; E. Goetz; L. Goggin; G. González; S. Gossler; R. Gouaty; A. Grant; S. Gras; C. Gray; M. Gray; R. J. S. Greenhalgh; A. M. Gretarsson; F. Grimaldi; R. Grosso; H. Grote; S. Grunewald; M. Guenther; E. K. Gustafson; R. Gustafson; B. Hage; J. M. Hallam; D. Hammer; C. Hanna; J. Hanson; J. Harms; G. Harry; E. Harstad; K. Hayama; T. Hayler; J. Heefner; I. S. Heng; M. Hennessy; A. Heptonstall; M. Hewitson; S. Hild; E. Hirose; D. Hoak; D. Hosken; J. Hough; S. H. Huttner; D. Ingram; M. Ito; A. Ivanov; B. Johnson; W. W. Johnson; D. I. Jones; G. Jones; R. Jones; L. Ju; P. Kalmus; V. Kalogera; S. Kamat; J. Kanner; D. Kasprzyk; E. Katsavounidis; K. Kawabe; S. Kawamura; F. Kawazoe; W. Kells; D. G. Keppel; F. Ya. Khalili; R. Khan; E. Khazanov; C. Kim; P. King; J. S. Kissel; S. Klimenko; K. Kokeyama; V. Kondrashov; R. K. Kopparapu; D. Kozak; I. Kozhevatov; B. Krishnan; P. Kwee; P. K. Lam; M. Landry; M. M. Lang; B. Lantz; A. Lazzarini; M. Lei; N. Leindecker; V. Leonhardt; I. Leonor; K. Libbrecht; H. Lin; P. Lindquist; N. A. Lockerbie; D. Lodhia; M. Lormand; P. Lu; M. Lubinski; A. Lucianetti; H. Lück; B. Machenschalk; M. MacInnis; M. Mageswaran; K. Mailand; V. Mandic; S. Márka; Z. Márka; A. Markosyan; J. Markowitz; E. Maros; I. Martin; R. M. Martin; J. N. Marx; K. Mason; F. Matichard; L. Matone; R. Matzner; N. Mavalvala; R. McCarthy; D. E. McClelland; S. C. McGuire; M. McHugh; G. McIntyre; G. McIvor; D. McKechan; K. McKenzie; T. Meier; A. Melissinos; G. Mendell; R. A. Mercer; S. Meshkov; C. J. Messenger; D. Meyers; J. Miller; J. Minelli; S. Mitra; V. P. Mitrofanov; G. Mitselmakher; R. Mittleman; O. Miyakawa; B. Moe; S. Mohanty; G. Moreno; K. Mossavi; C. MowLowry; G. Mueller; S. Mukherjee; H. Mukhopadhyay; H. Müller-Ebhardt; J. Munch; P. Murray; E. Myers; J. Myers; T. Nash; J. Nelson; G. Newton; A. Nishizawa; K. Numata; J. O'Dell; G. Ogin; B. O'Reilly; R. O'Shaughnessy; D. J. Ottaway; R. S. Ottens; H. Overmier; B. J. Owen; Y. Pan; C. Pankow; M. A. Papa; V. Parameshwaraiah; P. Patel; M. Pedraza; S. Penn; A. Perreca; T. Petrie; I. M. Pinto; M. Pitkin; H. J. Pletsch; M. V. Plissi; F. Postiglione; M. Principe; R. Prix; V. Quetschke; F. Raab; D. S. Rabeling; H. Radkins; N. Rainer; M. Rakhmanov; M. Ramsunder; H. Rehbein; S. Reid; D. H. Reitze; R. Riesen; K. Riles; B. Rivera; N. A. Robertson; C. Robinson; E. L. Robinson; S. Roddy; A. Rodriguez; A. M. Rogan; J. Rollins; J. D. Romano; J. Romie; R. Route; S. Rowan; A. Rüdiger; L. Ruet; P. Russell; K. Ryan; S. Sakata; M. Samidi; L. Sancho de la Jordana; V. Sandberg; V. Sannibale; S. Saraf; P. Sarin; B. S. Sathyaprakash; S. Sato; P. R. Saulson; R. Savage; P. Savov; S. W. Schediwy; R. Schilling; R. Schnabel; R. Schofield; B. F. Schutz; P. Schwinberg; S. M. Scott; A. C. Searle; B. Sears; F. Seifert; D. Sellers; A. S. Sengupta; P. Shawhan; D. H. Shoemaker; A. Sibley; X. Siemens; D. Sigg; S. Sinha; A. M. Sintes; B. J. J. Slagmolen; J. Slutsky; J. R. Smith; M. R. Smith; N. D. Smith; K. Somiya; B. Sorazu; L. C. Stein; A. Stochino; R. Stone; K. A. Strain; D. M. Strom; A. Stuver; T. Z. Summerscales; K. -X. Sun; M. Sung; P. J. Sutton; H. Takahashi; D. B. Tanner; R. Taylor; R. Taylor; J. Thacker; K. A. Thorne; K. S. Thorne; A. Thüring; K. V. Tokmakov; C. Torres; C. Torrie; G. Traylor; M. Trias; W. Tyler

2008-05-30T23:59:59.000Z

345

Might quantum-induced deviations from the Einstein equations detectably affect gravitational wave propagation?  

E-Print Network (OSTI)

A quantum measurement-like event can produce any of a number of macroscopically distinct results, with corresponding macroscopically distinct gravitational fields, from the same initial state. Hence the probabilistically evolving large-scale structure of space-time is not precisely or even always approximately described by the deterministic Einstein equations. Since the standard treatment of gravitational wave propagation assumes the validity of the Einstein equations, it is questionable whether we should expect all its predictions to be empirically verified. In particular, one might expect the stochasticity of amplified quantum indeterminacy to cause coherent gravitational wave signals to decay faster than standard predictions suggest. This need not imply that the radiated energy flux from gravitational wave sources differs from standard theoretical predictions. An underappreciated bonus of gravitational wave astronomy is that either detecting or failing to detect predicted gravitational wave signals would constrain the form of the semi-classical theory of gravity that we presently lack.

Adrian Kent

2013-04-17T23:59:59.000Z

346

Fuzzy multi-criteria decision making in stereovision matching for fish-eye lenses in forest analysis  

Science Conference Proceedings (OSTI)

This paper describes a novel stereovision matching approach based on omni-directional images obtained with fish-eye lenses in forest environments. The goal is to obtain a disparity map as a previous step for determining the volume of wood in the imaged ... Keywords: fish-eye stereo vision, fuzzy multi-criteria decision making, omni-directional forest images, stereovision matching

P. J. Herrera; G. Pajares; M. Guijarro; J. J. Ruz; J. M. De La Cruz

2009-09-01T23:59:59.000Z

347

arXiv:astro-ph/0208093v327Nov2002 Dark Energy and Matter Evolution from Lensing Tomography  

E-Print Network (OSTI)

arXiv:astro-ph/0208093v327Nov2002 Dark Energy and Matter Evolution from Lensing Tomography Wayne Hu on the growth function of structure and the evolution of the dark energy density. We examine this potential tests for the existence of multiple dark matter components or a dark energy component

Hu, Wayne

348

Understanding the Fundamental Properties of Dark Matter & Dark Energy in Structure formation and Cosmology  

Science Conference Proceedings (OSTI)

This program is concerned with developing and verifying the validityof observational methods for constraining the properties of dark matter and dark energy in the universe. Excellent progress has been made in comparing observational projects involving weak gravitational lensing using both ground and space-based instruments, in further constraining the nature of dark matter via precise measures of its distribution in clusters of galaxies using strong gravitational lensing, in demonstrating the possible limitations of using distant supernovae in future dark energy missions, and in investigating the requirement for ground-based surveys of baryonic acoustic oscillations.

Ellis, Richard, S.

2008-02-01T23:59:59.000Z

349

LISA and ground-based detectors for gravitational waves: An overview  

Science Conference Proceedings (OSTI)

The gravitational wave spectrum covers many decades in frequency. Sources in the audio-frequency regime above 1 Hz are accessible to ground-based detectors while sources in the low-frequency regime can only be observed from space because of the unshieldable background of local gravitational noise on the ground and because ground-based interferometers are limited in length to a few kilometers. Laser interferometry is a promising technique to observe the minute distance changes caused by gravitational waves

Karsten Danzmann LISA Study Team

1998-01-01T23:59:59.000Z

350

Probing strong-field gravity and black holes with gravitational waves  

E-Print Network (OSTI)

Gravitational wave observations will be excellent tools for making precise measurements of processes that occur in very strong- field regions of space time. Extreme mass

Hughes, Scott A.

351

On the problem of uniqueness of energy-momentum tensor of gravitational field  

E-Print Network (OSTI)

For an island-like distribution of matter the gravitational energy-momentum tensor is defined according to Weinberg as a source of metric. If this source is formed by self-interactions of gravitons, so that nonphysical degrees of freedom are excluded, then this source is a reasonable candidate for the energy-momentum tensor of gravitational field. The disastrous influence of the nonphysical degrees of freedom is demonstrated by comparing the gravitational energy-momentum tensors in the harmonic, isotropic and standard frames for the Schwarzschild solution. The harmonic frame is clearly preferable for defining the gravitational energy-momentum tensor.

A. I. Nikishov

2003-10-14T23:59:59.000Z

352

Anomalous effects due to the inertial anti-gravitational potential of the sun  

E-Print Network (OSTI)

It is introduced inertial anti-gravitational potential into the theory of gravity to stop gravitational collapse at the nuclear density and thus prevent singularities. It is considered effective gravity which includes Newtonian potential and inertial anti-gravitational potential. It is investigated footprints of the effective gravity in the solar system. The inertial anti-gravitational potential of the sun allows to explain the anomalous acceleration of Pioneer 10 and 11, the anomalous increase in the lunar semi-major axis, the residuals of the seasonal variation of the proper angular velocity of the earth, the anomalous increase of the Astronomical Unit, the anomalous shift of the perihelion of mercury.

D. L. Khokhlov

2007-10-31T23:59:59.000Z

353

Tests of Bayesian Model Selection Techniques for Gravitational Wave Astronomy  

E-Print Network (OSTI)

The analysis of gravitational wave data involves many model selection problems. The most important example is the detection problem of selecting between the data being consistent with instrument noise alone, or instrument noise and a gravitational wave signal. The analysis of data from ground based gravitational wave detectors is mostly conducted using classical statistics, and methods such as the Neyman-Pearson criteria are used for model selection. Future space based detectors, such as the \\emph{Laser Interferometer Space Antenna} (LISA), are expected to produced rich data streams containing the signals from many millions of sources. Determining the number of sources that are resolvable, and the most appropriate description of each source poses a challenging model selection problem that may best be addressed in a Bayesian framework. An important class of LISA sources are the millions of low-mass binary systems within our own galaxy, tens of thousands of which will be detectable. Not only are the number of sources unknown, but so are the number of parameters required to model the waveforms. For example, a significant subset of the resolvable galactic binaries will exhibit orbital frequency evolution, while a smaller number will have measurable eccentricity. In the Bayesian approach to model selection one needs to compute the Bayes factor between competing models. Here we explore various methods for computing Bayes factors in the context of determining which galactic binaries have measurable frequency evolution. The methods explored include a Reverse Jump Markov Chain Monte Carlo (RJMCMC) algorithm, Savage-Dickie density ratios, the Schwarz-Bayes Information Criterion (BIC), and the Laplace approximation to the model evidence. We find good agreement between all of the approaches.

Neil J. Cornish; Tyson B. Littenberg

2007-04-13T23:59:59.000Z

354

Gravitational Collapse and Radiation of Grand Unified Theory  

E-Print Network (OSTI)

The infinite gravitational collapse of any supermassive stars should pass through an energy scale of the grand unified theory (GUT). After nucleon-decays, the supermassive star will convert nearly all its mass into energy, and produce the radiation of GUT. It may probably explain some ultrahigh energy puzzles in astrophysics, for example, quasars and gamma-ray bursts (GRB), etc. This is similar with a process of the Big Bang Universe with a time-reversal evolution in much smaller space scale and mass scale. In this process the star seems be a true white hole.

Yi-Fang Chang

2007-10-02T23:59:59.000Z

355

Searching for Gravitational-Wave Bursts with LIGO  

E-Print Network (OSTI)

We present recent results from searches by the LIGO Science Collaboration for bursts of gravitational-wave radiation, as well as the status of other ongoing searches. These include directed searches for bursts associated with observed sources (gamma-ray bursts, soft gamma repeaters) and untriggered searches for bursts from unknown sources. We also present the status of some newer investigations, such as coherent network methods. We show methods for interpreting our search results in terms of astrophysical source distributions that improve their accessibility to the wider community.

K. A. Thorne

2007-06-28T23:59:59.000Z

356

Bayesian methods for gravitational waves and neural networks  

E-Print Network (OSTI)

can be found in [48]. Follow-up searches to find GWs associated with observed gamma-ray bursts have been performed [49] and studies are underway to cross-correlate GW and neutrino observations [50]. Gravitational wave detections can be used to test... in the detectors. These same tools and lessons can also be applied to the type of data expected from planned space-based detectors. Using simulations from the Mock LISA Data Challenges, I analyse our ability to detect and characterise both burst and continuous...

Graff, Philip B.

2012-10-09T23:59:59.000Z

357

Gravitation and regular Universe without dark energy and dark matter  

E-Print Network (OSTI)

It is shown that isotropic cosmology in the Riemann-Cartan spacetime allows to solve the problem of cosmological singularity as well as the problems of invisible matter components - dark energy and dark matter. All cosmological models filled with usual gravitating matter satisfying energy dominance conditions are regular with respect to energy density, spacetime metrics and the Hubble parameter. At asymptotics cosmological solutions of spatially flat models describe accelerating Universe without dark energy and dark matter, and quantitatively their behaviour is identical to that of standard cosmological \\Lambda CDM-model.

A. V. Minkevich

2011-02-03T23:59:59.000Z

358

Technical advantages for weak value amplification: When less is more  

E-Print Network (OSTI)

The technical merits of weak value amplification techniques are analyzed. We consider models of several different types of technical noise in an optical context and show that weak value amplification techniques (which only use a small fraction of the photons) compare favorably with standard techniques (which uses all of them). Using the Fisher information metric, we demonstrate that weak value techniques can put all of the Fisher information about the detected parameter into a small portion of the events and show how this fact alone gives technical advantages. We go on to consider a time correlated noise model, and find that a Fisher information analysis indicates that while the standard method can have much larger information about the detected parameter than the postselected technique. However, the estimator needed to gather the information is technically difficult to implement, showing that the inefficient (but practical) signal-to-noise estimation of the parameter is usually superior. We also describe other technical advantages unique to imaginary weak value amplification techniques, focusing on beam deflection measurements. In this case, we discuss combined noise types (such as detector transverse jitter, angular beam jitter before the interferometer and turbulence) for which the interferometric weak value technique gives higher Fisher information over conventional methods. We go on to calculate the Fisher information of the recently proposed photon recycling scheme for beam deflection measurements, and show it further boosts the Fisher information by the inverse postselection probability relative to the standard measurement case.

Andrew N. Jordan; Julián Martínez-Rincón; John C. Howell

2013-09-19T23:59:59.000Z

359

GRAVITATIONAL INSTABILITY OF ROTATING, PRESSURE-CONFINED, POLYTROPIC GAS DISKS WITH VERTICAL STRATIFICATION  

SciTech Connect

We investigate the gravitational instability (GI) of rotating, vertically stratified, pressure-confined, polytropic gas disks using a linear stability analysis as well as analytic approximations. The disks are initially in vertical hydrostatic equilibrium and bounded by a constant external pressure. We find that the GI of a pressure-confined disk is in general a mixed mode of the conventional Jeans and distortional instabilities, and is thus an unstable version of acoustic-surface-gravity waves. The Jeans mode dominates in weakly confined disks or disks with rigid boundaries. On the other hand, when the disk has free boundaries and is strongly pressure confined, the mixed GI is dominated by the distortional mode that is surface-gravity waves driven unstable under their own gravity and thus incompressible. We demonstrate that the Jeans mode is gravity-modified acoustic waves rather than inertial waves and that inertial waves are almost unaffected by self-gravity. We derive an analytic expression for the effective sound speed c{sub eff} of acoustic-surface-gravity waves. We also find expressions for the gravity reduction factors relative to a razor-thin counterpart that are appropriate for the Jeans and distortional modes. The usual razor-thin dispersion relation, after correcting for c{sub eff} and the reduction factors, closely matches the numerical results obtained by solving a full set of linearized equations. The effective sound speed generalizes the Toomre stability parameter of the Jeans mode to allow for the mixed GI of vertically stratified, pressure-confined disks.

Kim, Jeong-Gyu; Kim, Woong-Tae [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Seo, Young Min; Hong, Seung Soo, E-mail: jgkim@astro.snu.ac.kr, E-mail: wkim@astro.snu.ac.kr, E-mail: seo3919@email.arizona.edu, E-mail: sshong@astro.snu.ac.kr [FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

2012-12-20T23:59:59.000Z

360

Verifying the no-hair property of massive compact objects with intermediate-mass-ratio inspirals in advanced gravitational-wave detectors  

E-Print Network (OSTI)

The detection of gravitational waves from the inspiral of a neutron star or stellar-mass black hole into an intermediate-mass black hole (IMBH) promises an entirely new look at strong-field gravitational physics. Gravitational ...

Gair, Jonathan R.

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361

Malaria Researchers Find Weakness in Global Killer | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Malaria Researchers Find Weakness in Global Killer Malaria Researchers Find Weakness in Global Killer Malaria Researchers Find Weakness in Global Killer February 1, 2012 - 9:16am Addthis The protozoan Plasmodium falciparum gliding through a cell in the gut of a mosquito, its primary host. Although five different species of Plasmodium can cause malaria, Plasmodium falciparum causes the most severe disease. | Photo courtesy of Wikipedia Commons. The protozoan Plasmodium falciparum gliding through a cell in the gut of a mosquito, its primary host. Although five different species of Plasmodium can cause malaria, Plasmodium falciparum causes the most severe disease. | Photo courtesy of Wikipedia Commons. Charles Rousseaux Charles Rousseaux Senior Writer, Office of Science

362

Role of Weak Ties in Link Prediction of Complex Networks  

E-Print Network (OSTI)

Plenty of algorithms for link prediction have been proposed and were applied to various real networks. Among these works, the weights of links are rarely taken into account. In this paper, we use local similarity indices to estimate the likelihood of the existence of links in weighted networks, including Common Neighbor, Adamic-Adar Index, Resource Allocation Index, and their weighted versions. In both the unweighted and weighted cases, the resource allocation index performs the best. To our surprise, the weighted indices perform worse, which reminds us of the well-known Weak Tie Theory. Further extensive experimental study shows that the weak ties play a significant role in the link prediction problem, and to emphasize the contribution of weak ties can remarkably enhance the predicting accuracy.

Lu, Linyuan

2009-01-01T23:59:59.000Z

363

Mechanical and acoustic properties of weakly cemented granular rocks  

SciTech Connect

This paper presents the results of laboratory measurements on the mechanical and acoustic properties of weakly cemented granular rock. Artificial rock samples were fabricated by cementing sand and glass beads with sodium silicate binder. During uniaxial compression tests, the rock samples showed stress-strain behavior which was more similar to that of soils than competent rocks, exhibiting large permanent deformations with frictional slip. The mechanical behavior of the samples approached that of competent rocks as the amount of binder was increased. For very weak samples, acoustic waves propagating in these rocks showed very low velocities of less than 1000 m/sec for compressional waves. A borehole made within this weakly cemented rock exhibited a unique mode of failure that is called ''anti-KI mode fracture'' in this paper. The effect of cementation, grain type, and boundary conditions on this mode of failure was also examined experimentally.

Nakagawa, S.; Myer, L.R.

2001-05-09T23:59:59.000Z

364

Observing the Galaxy's massive black hole with gravitational wave bursts  

E-Print Network (OSTI)

An extreme-mass-ratio burst (EMRB) is a gravitational wave signal emitted when a compact object passes through periapsis on a highly eccentric orbit about a much more massive object, in our case a stellar mass object about a 10^6 M_sol black hole. EMRBs are a relatively unexplored means of probing the spacetime of massive black holes (MBHs). We conduct an investigation of the properties of EMRBs and how they could allow us to constrain the parameters, such as spin, of the Galaxy's MBH. We find that if an EMRB event occurs in the Galaxy, it should be detectable for periapse distances r_p < 65 r_g for a \\mu = 10 M_sol orbiting object, where r_g = GM/c^2 is the gravitational radius. The signal-to-noise ratio scales as \\rho ~ -2.7 log(r_p/r_g) + log(\\mu/M_sol) + 4.9. For periapses r_p < 10 r_g, EMRBs can be informative, and provide good constraints on both the MBH's mass and spin. Closer orbits provide better constraints, with the best giving accuracies of better than one part in 10^4 for both the mass and ...

Berry, C P L

2012-01-01T23:59:59.000Z

365

New directions for gravitational wave physics via "Millikan oil drops"  

E-Print Network (OSTI)

"Millikan oil drops" are drops of superfluid helium coated with electrons, and levitated in a strong, inhomogeneous magnetic field. When the temperature of the system becomes very low compared to the cyclotron gap energy, the system remains in its quantum ground state. Two such levitated charged drops can have their charge-to-mass ratio critically adjusted so that the forces of gravity and electricity between the drops are in balance. Then it is predicted that the amount of scattered electromagnetic and gravitational radiation from the drops are equalized, along with these two kinds of forces. The cross sections for the scattering of the two kinds of radiation can become large, hard-sphere cross-sections at the first Mie resonance, due to the hard-wall boundary conditions on the surfaces of the spheres for both kinds of radiations. An efficient quantum transduction process between electromagnetic and gravitational radiation by such a pair of drops is predicted at microwave frequencies, and a Hertz-like experiment is proposed. A more practical implementation of these ideas to use pairs of levitated, charged superconducting spheres is briefly discussed.

Raymond Y. Chiao

2009-04-25T23:59:59.000Z

366

Geometric gravitational origin of neutrino oscillations and mass-energy  

E-Print Network (OSTI)

A mass-energy scale for neutrinos was calculated from the null cone curvature using geometric concepts. The scale is variable depending on the gravitational potential and the trajectory inclination with respect to the field direction. The mass-energy at the Earth surface varies from a horizontal value 0.402 eV to a vertical value 0.569 eV. Earth spinor waves with winding numbers n show squared energy differences within ranges from 2.05 x 10*(-3) to 4.10 x 10*(-3) eV*2 for n=0,1 neutrinos and from 3.89 x 10*(-5) to 7.79 x 10*(-5) eV*2 for n=1,2 neutrinos. These waves interfere and the different phase velocities produce neutrino-like oscillations. The experimental results for atmospheric and solar neutrino oscillation mass parameters respectivelly fall within these theoretical ranges. Neutrinos in outer space, where interactions may be neglected, appear as particles travelling with zero mass on null geodesics. These gravitational curvature energies are consistent with neutrino oscillations, zero neutrino rest masses and Einstein's General Relativity and energy mass equivalence principle. When analyzing or averaging experimental neutrino mass-energy results of different experiments on the Earth it is of interest to consider the possible influence of the trajectory inclination angle.

Gustavo R. Gonzalez-Martin

2012-12-10T23:59:59.000Z

367

Charge Management for Gravitational Wave Observatories using UV LEDs  

E-Print Network (OSTI)

Accumulation of electrical charge on the end mirrors of gravitational wave observatories, such as the space-based LISA mission and ground-based LIGO detectors, can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable Au-coated Cu plate brought near a Au-coated Si plate pendulum suspended from a non-conducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging of the pendulum with equivalent charging rates of $\\sim$$10^5 e/\\mathrm{s}$, as well as spectral measurements of the pendulum charge resulting in a white noise level equivalent to $3\\times10^5 e/\\sqrt{Hz}$.

S. E. Pollack; M. D. Turner; S. Schlamminger; C. A. Hagedorn; J. H. Gundlach

2009-12-09T23:59:59.000Z

368

Events trigger generator for resonant spherical detectors of gravitational waves  

E-Print Network (OSTI)

We have set up and tested a pipeline for processing the data from a spherical gravitational wave detector with six transducers. The algorithm exploits the multichannel capability of the system and provides a list of candidate events with their arrival direction. The analysis starts with the conversion of the six detector outputs into the scalar and the five quadrupolar modes of the sphere, which are proportional to the corresponding gravitational wave spherical components. Event triggers are then generated by an adaptation of the WaveBurst algorithm. Event validation and direction reconstruction are made by cross-checking two methods of different inspiration: geometrical (lowest eigenvalue) and probabilistic (maximum likelihood). The combination of the two methods is able to keep substantially unaltered the efficiency and can reduce drastically the detections of fake events (to less than ten per cent). We show a quantitative test of these ideas by simulating the operation of the resonant spherical detector miniGRAIL, whose planned sensitivity in its frequency band (few hundred Hertz's around 3 kHz) is comparable with the present LIGO one.

Stefano Foffa; Riccardo Sturani

2008-05-06T23:59:59.000Z

369

Coherent detection method of gravitational wave bursts for spherical antennas  

E-Print Network (OSTI)

We provide a comprehensive theoretical framework and a quantitative test of the method we recently proposed for processing data from a spherical detector with five or six transducers. Our algorithm is a trigger event generator performing a coherent analysis of the sphere channels. In order to test our pipeline we first built a detailed numerical model of the detector, including deviations from the ideal case such as quadrupole modes splitting, and non-identical transducer readout chains. This model, coupled with a Gaussian noise generator, has then been used to produce six time series, corresponding to the outputs of the six transducers attached to the sphere. We finally injected gravitational wave burst signals into the data stream, as well as bursts of non-gravitational origin in order to mimic the presence of non-Gaussian noise, and then processed the mock data. We report quantitative results for the detection efficiency versus false alarm rate and for the affordability of the reconstruction of the direction of arrival. In particular, the combination of the two direction reconstruction methods can reduce by a factor of 10 the number false alarms due to the non-Gaussian noise.

S. Foffa; R. Sturani

2008-12-22T23:59:59.000Z

370

Geometric gravitational origin of neutrino oscillations and mass-energy  

E-Print Network (OSTI)

A mass-energy scale for neutrinos was calculated from the null cone curvature using geometric concepts. The scale is variable depending on the gravitational potential and the trajectory inclination with respect to the field direction. The proposed neutrino covariant equation provides the adequate curvature. The mass-energy at the Earth surface varies from a horizontal value 0.402 eV to a vertical value 0.569 eV. Earth spinor waves with winding numbers n show squared energy differences within ranges from 2.05 x 10*(-3) to 4.10 x 10*(-3) eV*2 for n=0,1 neutrinos and from 3.89 x 10*(-5) to 7.79 x 10*(-5) eV*2 for n=1,2 neutrinos. These waves interfere and the different phase velocities produce neutrino-like oscillations. The experimental results for atmospheric and solar neutrino oscillation mass parameters respectivelly fall within these theoretical ranges. Neutrinos in outer space, where interactions may be neglected, appear as particles travelling with zero mass on null geodesics. These gravitational curvature energies are consistent with neutrino oscillations, zero neutrino rest masses and Einstein's General Relativity and energy mass equivalence principle. When analyzing or averaging experimental neutrino mass-energy results of different experiments on the Earth it is of interest to consider the possible influence of the trajectory inclination angle.

Gustavo R. Gonzalez-Martin

2012-12-10T23:59:59.000Z

371

Reissner-Nordström Spacetime in the Tetrad Theory of Gravitation  

E-Print Network (OSTI)

We give two classes of spherically symmetric exact solutions of the couple gravitational and electromagnetic fields with charged source in the tetrad theory of gravitation. The first solution depends on an arbitrary function $H({R},t)$. The second solution depends on a constant parameter $\\eta$. These solutions reproduce the same metric, i.e., the Reissner--Nordstr$\\ddot{o}$m metric. If the arbitrary function which characterizes the first solution and the arbitrary constant of the second solution are set to be zero, then the two exact solutions will coincide with each other. We then calculate the energy content associated with these analytic solutions using the superpotential method. In particular, we examine whether these solutions meet the condition which M{\\o}ller required for a consistent energy-momentum complex: Namely, we check whether the total four-momentum of an isolated system behaves as a four-vector under Lorentz transformations. It is then found that the arbitrary function should decrease faster than $1/\\sqrt{R}$ for $R\\to \\infty$. It is also shown that the second exact solution meets the M{\\o}ller's condition.

Gamal G. L. Nashed; Takeshi Shirafuji

2007-04-30T23:59:59.000Z

372

QCD Corrections to Jet Correlations in Weak Boson Fusion  

E-Print Network (OSTI)

Higgs boson production via weak boson fusion is sensitive to the tensor structure of the HVV (V=W,Z) couplings, which distinguishes loop induced vertices from SM expectations. At the CERN Large Hadron Collider this information shows up most clearly in the azimuthal angle correlations of the two forward and backward quark jets which are typical for weak boson fusion. We calculate the next-to-leading order QCD corrections to this process, in the presence of anomalous HVV couplings. Gluon emission does not significantly change the azimuthal jet correlations.

Terrance Figy; Dieter Zeppenfeld

2004-03-30T23:59:59.000Z

373

Algebraic Definition of weak ($\\infty$; n)-Categories.  

E-Print Network (OSTI)

In this paper we define a sequence of monads $\\mathbb{T}^(\\infty;n)$ $(n\\in\\mathbb{N})$ on $\\infty$-$\\mathbb{G}\\text{r}$, the category of the $\\infty$-graphs. We conjecture that algebras for $\\mathbb{T}^(0;n)$ which are defined in a purely algebraic setting, are models of weak $\\infty$-groupoids. And for all $n>1$ we conjecture that algebras for $\\mathbb{T}^(\\infty;n)$ which are defined in a purely algebraic setting, are models of weak $(\\infty; n)$-categories.

Camell Kachour

374

A Chemical Potential 'Battery' for Superfluid 4He Weak Links  

Science Conference Proceedings (OSTI)

Research and development of superfluid weak links has been hindered by the absence of a source of dc chemical potential, similar to a simple battery or voltage source for analogous superconducting devices. We describe here a method for generating a dc chemical potential difference, {delta}{mu} across a weak link array in superfluid 4He. The presence of a {delta}{mu} forces quantum oscillations at a Josephson frequency, selectable by the adjustment of input power to a heater. We discuss a case in which the frequency locks onto a resonance feature where it exhibits remarkable stability, and amplitude magnification by a factor of 40.

Hoskinson, E.; Sato, Y.; Packard, R. E. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Penanen, K. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2006-09-07T23:59:59.000Z

375

Persistent Currents in the Heisenberg chain with a weak link  

E-Print Network (OSTI)

The Heisenberg chain with a weak link is studied, as a simple example of a quantum ring with a constriction or defect. The Heisenberg chain is equivalent to a spinless electron gas under a Jordan-Wigner transformation. Using density matrix renormalization group and quantum Monte Carlo methods we calculate the spin/charge stiffness of the model, which determines the strength of the ‘persistent currents’. The stiffness is found to scale to zero in the weak link case, in agreement with renormalization group arguments of Eggert and Affleck, and Kane and Fisher.

T. M. R. Byrnes; R. J. Bursill; H. -p. Eckle; C. J. Hamer; A. W. Sandvik

2002-01-01T23:59:59.000Z

376

Design of a Quantum Source of High-Frequency Gravitational Waves (HFGW) and Test Methodology  

E-Print Network (OSTI)

The generation of High-Frequency Gravitational Waves (HFGW) has been identified as the required breakthrough that will lead to new forms of space propulsion. Many techniques have been devised to generate HFGW, but most of them exhibit marginal efficiency, therefore the power emitted in form of gravitational waves (GW) is orders of magnitude lower than the input power. The gravitational wave counterpart of the LASER, termed Gravitational-wave LASER or "GASER" is the quantum approach to the efficient generation of gravitational waves. Electrons, protons, muons, etc, all have charge and mass, if accelerated they usually lose energy through the very fast electric and magnetic channels, this causes a negligible emission through the gravitational channel. Quantum systems can be engineered to forbid electric and magnetic transitions, therefore the gravitational spin-2 transitions can take place. A class of active materials, suitable for making a GASER based on electronic transitions in the solid state, is identified along with their relevant physical properties. Means for creating coherence and population inversion and means to increase the emission probability are described. The expected performances of the device are derived from quantum gravitational theories. Additional properties of the active materials are considered to enforce the theoretical foundation of the device. A proof-of-concept device, operating at about 1 THz, is described. Experiments are proposed as a natural starting point of the research.

Giorgio Fontana

2004-10-04T23:59:59.000Z

377

Wave polarizations for a beam-like gravitational wave in quadratic curvature gravity  

E-Print Network (OSTI)

We compute analytically the tidal field and polarizations of an exact gravitational wave generated by a cylindrical beam of null matter of finite width and length in quadratic curvature gravity. We propose that this wave can represent the gravitational wave that keep up with the high energy photons produced in a gamma ray burst (GRB) source.

E. C. de Rey Neto; J. C. N. de Araujo; O. D. Aguiar

2003-11-14T23:59:59.000Z

378

The Active Gravitational Mass of a Heat Conducting Sphere Out of Hydrostatic Equilibrium  

E-Print Network (OSTI)

We obtain an expression for the active gravitational mass of a relativistic heat conducting fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of relaxation time. It is shown that an increase of a characteristic parameter leads to larger (smaller) values of active gravitational mass of collapsing (expanding) spheres, enhacing thereby the instability of the system.

L. Herrera; A. Di Prisco

1998-10-06T23:59:59.000Z

379

Fifth ASTROD Symposium and Outlook of Direct Gravitational-Wave Detection  

E-Print Network (OSTI)

From July 11 to July 13, 2012, Raman Research Institute (Bangalore, India) hosted the Fifth International ASTROD Symposium on Laser Astrodynamics, Space Test of Relativity and Gravitational-Wave Astronomy. This is a report on the symposium with an exposition of the outlook of direct gravitational-wave detection.

Arun, K G; Ni, Wei-Tou

2012-01-01T23:59:59.000Z

380

Fifth ASTROD Symposium and Outlook of Direct Gravitational-Wave Detection  

E-Print Network (OSTI)

From July 11 to July 13, 2012, Raman Research Institute (Bangalore, India) hosted the Fifth International ASTROD Symposium on Laser Astrodynamics, Space Test of Relativity and Gravitational-Wave Astronomy. This is a report on the symposium with an exposition of the outlook of direct gravitational-wave detection.

K. G. Arun; Bala R. Iyer; Wei-Tou Ni

2012-10-28T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

A directed search for continuous Gravitational Waves from the Galactic Center  

E-Print Network (OSTI)

We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic Center region, performed on two years of data from LIGO's fifth science run from two LIGO detectors. The search uses a semi-coherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first order spindown values down to -7.86 x 10^-8 Hz/s at the highest frequency. No gravitational waves were detected. We place 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic Center. Reaching ~3.35 x 10^-25 at ~150 Hz, those upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.

Aasi, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Accadia, T; Acernese, F; Adams, C; Adams, T; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Allen, B; Allocca, A; Ceron, E Amador; Amariutei, D; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barker, D; Barnum, S H; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J; Bauchrowitz, J; Bauer, Th S; Bebronne, M; Behnke, B; Bejger, M; Beker, M G; Bell, A S; Bell, C; Belopolski, I; Bergmann, G; Berliner, J M; Bertolini, A; Bessis, D; Betzwieser, J; Beyersdorf, P T; Bhadbhade, T; Bilenko, I A; Billingsley, G; Birch, J; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Blom, M; Bock, O; Bodiya, T P; Boer, M; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Bose, S; Bosi, L; Bowers, J; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brannen, C A; Brau, J E; Breyer, J; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A; Caudill, S; Cavagliá, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Colombini, M; Constancio, M; Conte, A; Conte, R; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Craig, K; Creighton, J D E; Creighton, T D; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; De Rosa, R; Debreczeni, G; Degallaix, J; Del Pozzo, W; Deleeuw, E; Deléglise, S; Denker, T; Dent, T; Dereli, H; Dergachev, V; DeRosa, R; DeSalvo, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Díaz, M; Dietz, A; Dmitry, K; Donovan, F; Dooley, K L; Doravari, S; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dumas, J -C; Dwyer, S; Eberle, T; Edwards, M; Effler, A; Ehrens, P; Eichholz, J; Eikenberry, S S; Endröczi, G; Essick, R; Etzel, T; Evans, K; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farr, B; Farr, W; Favata, M; Fazi, D; Fehrmann, H; Feldbaum, D; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R; Flaminio, R; Foley, E; Foley, S; Forsi, E; Forte, L A; Fotopoulos, N; Fournier, J -D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fujimoto, M -K; Fulda, P; Fyffe, M; Gair, J; Gammaitoni, L; Garcia, J; Garufi, F; Gehrels, N; Gemme, G; Genin, E; Gennai, A; Gergely, L; Ghosh, S; Giaime, J A; Giampanis, S; Giardina, K D; Giazotto, A; Gil-Casanova, S; Gill, C; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Griffo, C; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C; Gushwa, K E; Gustafson, E K; Gustafson, R; Hall, B; Hall, E; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hartman, M T; Haughian, K; Hayama, K; Heefner, J; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Holtrop, M; Hong, T; Hooper, S; Horrom, T; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Hua, Z; Huang, V; Huerta, E A; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Iafrate, J; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jang, Y J; Jaranowski, P; Jiménez-Forteza, F; Johnson, W W; Jones, D; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kasprzack, M; Kasturi, R; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufman, K; Kawabe, K; Kawamura, S; Kawazoe, F; Kéfélian, F; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, B K; Kim, C; Kim, K; Kim, N; Kim, W; Kim, Y -M; King, E J

2013-01-01T23:59:59.000Z

382

Astrophysical weak-interaction processes and nuclear effective field theory  

E-Print Network (OSTI)

Low-energy nuclear weak-interaction processes play important roles in many astrophysical contexts, and effective field theory is believed to be a highly useful framework for describing these processes in a model-independent manner. I present a brief account of the basic features of the nuclear effective theory approach, and some examples of actual calculations carried out in this method.

K. Kubodera

2004-04-09T23:59:59.000Z

383

Microscopic scattering theory for interacting bosons in weak random potentials  

E-Print Network (OSTI)

We develop a diagrammatic scattering theory for interacting bosons in a three-dimensional, weakly disordered potential. Based on a microscopic N-body scattering theory, we identify the relevant diagrams including elastic and inelastic collision processes that are sufficient to describe diffusive quantum transport. By taking advantage of the statistical properties of the weak disorder potential, we demonstrate how the N-body dynamics can be reduced to a nonlinear integral equation of Boltzmann type for the single-particle diffusive flux. Our theory reduces to the Gross-Pitaevskii mean field description in the limit where only elastic collisions are taken into account. However, even at weak interaction strength, inelastic collisions lead to energy redistribution between the bosons - initially prepared all at the same single-particle energy - and thereby induce thermalization of the single-particle current. In addition, we include also weak localization effects and determine the coherent corrections to the incoherent transport in terms of the coherent backscattering signal. We find that inelastic collisions lead to an enhancement of the backscattered cone in a narrow spectral window for increasing interaction strength.

Tobias Geiger; Andreas Buchleitner; Thomas Wellens

2013-07-18T23:59:59.000Z

384

Higgs Production by Gluon initiated Weak Boson Fusion  

E-Print Network (OSTI)

The gluon-gluon induced terms for Higgs production through weak-boson fusion are calculated. They form a finite and gauge-invariant subset of the NNLO corrections in the strong coupling constant. This is also the lowest order with sizeable t-channel colour exchange contributions, leading to additional hadronic activity between the outgoing jets.

M. M. Weber

2007-09-17T23:59:59.000Z

385

On the steady states of weakly reversible chemical reaction networks  

E-Print Network (OSTI)

A natural condition on the structure of the underlying chemical reaction network, namely weak reversibility, is shown to guarantee the existence of an equilibrium (steady state) in each positive stoichiometric compatibility class for the associated mass-action system. Furthermore, an index formula is given for the set of equilibria in a given stoichiometric compatibility class.

Deng, Jian; Feinberg, Martin; Nachman, Adrian

2011-01-01T23:59:59.000Z

386

A Weakly Nonlinear Primitive Equation Baroclinic Life Cycle  

Science Conference Proceedings (OSTI)

A weakly nonlinear baroclinic life cycle is examined with a spherical, multilevel, primitive equation model. The structure of the initial zonal jet is chosen so that the disturbance grows very slowly, that is, linear growth rate less than 0.1 day?...

Steven B. Feldstein

1994-01-01T23:59:59.000Z

387

Effective cavity pumping from weakly coupled quantum dots  

E-Print Network (OSTI)

We derive the effective cavity pumping and decay rates for the master equation of a quantum dot-microcavity system in presence of $N$ weakly coupled dots. We show that the in-flow of photons is not linked to the out-flow by thermal equilibrium relationships.

del Valle, E

2010-01-01T23:59:59.000Z

388

Design and imaging performance of achromatic diffractive/refractive X-ray and Gamma-ray Fresnel lenses  

E-Print Network (OSTI)

Achromatic combinations of a diffractive Phase Fresnel Lens and a refractive correcting element have been proposed for X-ray and gamma-ray astronomy and for microlithography, but considerations of absorption often dictate that the refractive component be given a stepped profile, resulting in a double Fresnel lens. The imaging performance of corrected Fresnel lenses, with and without `stepping' is investigated and the trade-off between resolution and useful bandwidth in different circumstances is discussed. Provided the focal ratio is large, correction lenses made of low atomic number materials can be used with X-rays in the range approximately 10--100 keV without stepping. The use of stepping extends the possibility of correction to higher aperture systems, to energies as low as a few kilo electron volts and to gamma-rays of $\\sim$ mega electron volt energy.

Gerald K. Skinner

2004-07-21T23:59:59.000Z

389

Search for continuous gravitational waves: improving robustness versus instrumental artifacts  

E-Print Network (OSTI)

The standard multi-detector F-statistic for continuous gravitational waves is susceptible to false alarms from instrumental artifacts, for example monochromatic sinusoidal disturbances (lines). This vulnerability to line artifacts arises because the F-statistic compares the signal hypothesis to a Gaussian-noise hypothesis, and hence is triggered by anything that resembles the signal hypothesis more than Gaussian noise. Various ad-hoc veto methods to deal with such line artifacts have been proposed and used in the past. Here we develop a Bayesian framework that includes an explicit alternative hypothesis to model disturbed data. We introduce a simple line model that defines lines as signal candidates appearing only in one detector. This allows us to explicitly compute the odds between the signal hypothesis and an extended noise hypothesis, resulting in a new detection statistic that is more robust to instrumental artifacts. We present and discuss results from Monte-Carlo tests on both simulated data and on det...

Keitel, David; Papa, Maria Alessandra; Leaci, Paola; Siddiqi, Maham

2013-01-01T23:59:59.000Z

390

A Xylophone Configuration for a third Generation Gravitational Wave Detector  

E-Print Network (OSTI)

Achieving the demanding sensitivity and bandwidth, envisaged for third generation gravitational wave (GW) observatories, is extremely challenging with a single broadband interferometer. Very high optical powers (Megawatts) are required to reduce the quantum noise contribution at high frequencies, while the interferometer mirrors have to be cooled to cryogenic temperatures in order to reduce thermal noise sources at low frequencies. To resolve this potential conflict of cryogenic test masses with high thermal load, we present a conceptual design for a 2-band xylophone configuration for a third generation GW observatory, composed of a high-power, high-frequency interferometer and a cryogenic low-power, low-frequency instrument. Featuring inspiral ranges of 3200Mpc and 38000Mpc for binary neutron stars and binary black holes coalesences, respectively, we find that the potential sensitivity of xylophone configurations can be significantly wider and better than what is possible in a single broadband interferometer.

Stefan Hild; Simon Chelkowski; Andreas Freise; Janyce Franc; Nazario Morgado; Raffaele Flaminio; Riccardo DeSalvo

2009-06-15T23:59:59.000Z

391

Ultracold-neutron infrastructure for the gravitational spectrometer GRANIT  

E-Print Network (OSTI)

The gravitational spectrometer GRANIT will be set up at the Institut Laue Langevin. It will profit from the high ultracold neutron density produced by a dedicated source. A monochromator made of crystals from graphite intercalated with potassium will provide a neutron beam with 0.89 nm incident on the source. The source employs superthermal conversion of cold neutrons in superfluid helium, in a vessel made from BeO ceramics with Be windows. A special extraction technique has been tested which feeds the spectrometer only with neutrons with a vertical velocity component v < 20 cm/s, thus keeping the density in the source high. This new source is expected to provide a density of up to 800 1/cm3 for the spectrometer.

P. Schmidt-Wellenburg; K. H. Andersen; P. Courtois; M. Kreuz; S. Mironov; V. V. Nesvizhevsky; G. Pignol; K. V. Protasov; T. Soldner; F. Vezzu; O. Zimmer

2008-11-11T23:59:59.000Z

392

Laser Ranging for Gravitational, Lunar, and Planetary Science  

E-Print Network (OSTI)

More precise lunar and Martian ranging will enable unprecedented tests of Einstein's theory of General Relativity and well as lunar and planetary science. NASA is currently planning several missions to return to the Moon, and it is natural to consider if precision laser ranging instruments should be included. New advanced retroreflector arrays at carefully chosen landing sites would have an immediate positive impact on lunar and gravitational studies. Laser transponders are currently being developed that may offer an advantage over passive ranging, and could be adapted for use on Mars and other distant objects. Precision ranging capability can also be combined with optical communications for an extremely versatile instrument. In this paper we discuss the science that can be gained by improved lunar and Martian ranging along with several technologies that can be used for this purpose.

Stephen M. Merkowitz; Philip W. Dabney; Jeffrey C. Livas; Jan F. McGarry; Gregory A. Neumann; Thomas W. Zagwodzki

2007-12-20T23:59:59.000Z

393

Gravitational Model of High Energy Particles in a Collimated Jet  

E-Print Network (OSTI)

Observations suggest that relativistic particles play a fundamental role in the dynamics of jets emerging from active galactic nuclei as well as in their interaction with the intracluster medium. However, no general consensus exists concerning the acceleration mechanism of those high energy particles. A gravitational acceleration mechanism is here proposed, in which particles leaving precise regions within the ergosphere of a rotating supermassive black hole produce a highly collimated flow. These particles follow unbound geodesics which are asymptotically parallel to the spin axis of the black hole and are characterized by the energy $E$, the Carter constant ${\\cal Q}$ and zero angular momentum of the component $L_z$. If environmental effects are neglected, the present model predicts at distances of about 140 kpc from the ergosphere the presence of electrons with energies around 9.4 GeV. The present mechanism can also accelerate protons up to the highest energies observed in cosmic rays by the present experiments.

J. A. de Freitas Pacheco; J. Gariel; G. Marcilhacy; N. O. Santos

2012-10-02T23:59:59.000Z

394

Searching for electromagnetic counterparts of gravitational wave transients  

E-Print Network (OSTI)

A pioneering electromagnetic (EM) observation follow-up program of candidate gravitational wave (GW) triggers has been performed, Dec 17 2009 to Jan 8 2010 and Sep 4 to Oct 20 2010, during the recent LIGO/Virgo run. The follow-up program involved ground-based and space EM facilities observing the sky at optical, X-ray and radio wavelengths. The joint GW/EM observation study requires the development of specific image analysis procedures able to discriminate the possible EM counterpart of GW trigger from background events. The paper shows an overview of the EM follow-up program and the developing image analysis procedures as they are applied to data collected with TAROT and Zadko.

M. Branchesi; on behalf of the LIGO Scientific Collaboration; the Virgo Collaboration; A. Klotz; M. Laas-Bourez

2011-10-14T23:59:59.000Z

395

Neutron lifetime measurements using gravitationally trapped ultracold neutrons  

E-Print Network (OSTI)

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.

A. P. Serebrov; V. E. Varlamov; A. G. Kharitonov; A. K. Fomin; Yu. N. Pokotilovski; P. Geltenbort; I. A. Krasnoschekova; M. S. Lasakov; R. R. Taldaev; A. V. Vassiljev; O. M. Zherebtsov

2007-02-06T23:59:59.000Z

396

THE STRUCTURE OF GRAVITATIONALLY UNSTABLE GAS-RICH DISK GALAXIES  

Science Conference Proceedings (OSTI)

We use a series of idealized, numerical smoothed particle hydrodynamics simulations to study the formation and evolution of galactic, gas-rich disks forming from gas infall within dark matter halos. The temperature and density structure of the gas is varied in order to differentiate between (1) simultaneous gas infall at a large range of radii and (2) the inside-out buildup of a disk. In all cases, the disks go through phases of ring formation, gravitational instability and break-up into massive clumps. Ring formation can be enhanced by a focal point effect. The position of the ring is determined by the angular momentum distribution of the material it forms from. We study the ring and clump morphologies, the characteristic properties of the resulting velocity dispersion field and the effect of star formation. In the early phases, gas accretion leads to a high vertical velocity dispersion. We find that the disk fragmentation by gravitational instability and the subsequent clump-clump interactions drive high velocity dispersions mainly in the plane of the disk while at the same time the vertical velocity dispersion dissipates. The result is a strong variation of the line-of-sight velocity dispersion with inclination angle. For a face-on view, clumps appear as minima in the (vertical) dispersion, whereas for a more edge-on view, they tend to correspond to maxima. There exists observational evidence of a systematic variation of the velocity dispersion with inclination angle in high-redshift disks, which could be partly explained by our simulation results. Additional energetic sources to drive velocity dispersion that are not included in our models are also expected to contribute to the observational results.

Aumer, Michael; Burkert, Andreas; Johansson, Peter H. [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany); Genzel, Reinhard, E-mail: aumer@usm.lmu.d, E-mail: burkert@usm.lmu.d, E-mail: pjohan@usm.lmu.d, E-mail: genzel@mpe.mpg.d [UC Berkeley Department of Physics, Berkeley, CA 94720 (United States)

2010-08-20T23:59:59.000Z

397

Practical speed meter designs for QND gravitational-wave interferometers  

E-Print Network (OSTI)

In the quest to develop viable designs for third-generation optical interferometric gravitational-wave detectors (e.g., LIGO-III and EURO), one strategy is to monitor the relative momentum or speed of the test-mass mirrors, rather than monitoring their relative position. A previous paper analyzed a straightforward but impractical design for a {\\it speed-meter interferometer} that accomplishes this. This paper describes some practical variants of speed-meter interferometers. Like the original interferometric speed meter, these designs {\\it in principle} can beat the gravitational-wave standard quantum limit (SQL) by an arbitrarily large amount, over an arbitrarily wide range of frequencies. These variants essentially consist of a Michelson interferometer plus an extra "sloshing" cavity that sends the signal back into the interferometer with opposite phase shift, thereby cancelling the position information and leaving a net phase shift proportional to the relative velocity. {\\it In practice}, the sensitivity of these variants will be limited by the maximum light power $W_{\\rm circ}$ circulating in the arm cavities that the mirrors can support and by the leakage of vacuum into the optical train at dissipation points. In the absence of dissipation and with a squeezed vacuum of power squeeze factor ~ 0.1 inserted into the output port so as to keep the circulating power down, the SQL can be beat by a factor 10 in power at all frequencies below some chosen $f_{\\rm opt}\\simeq 100$ Hz, with $W_{\\rm circ}\\simeq 800$ kW. Estimates are given of the amount by which vacuum leakage at dissipation points will debilitate this sensitivity; these losses are 10% or less over most of the frequency range of interest.

Patricia Purdue; Yanbei Chen

2002-08-17T23:59:59.000Z

398

MIGRATION OF GAS GIANT PLANETS IN GRAVITATIONALLY UNSTABLE DISKS  

Science Conference Proceedings (OSTI)

Characterization of migration in gravitationally unstable disks is necessary to understand the fate of protoplanets formed by disk instability. As part of a larger study, we are using a three-dimensional radiative hydrodynamics code to investigate how an embedded gas giant planet interacts with a gas disk that undergoes gravitational instabilities (GIs). This Letter presents results from simulations with a Jupiter-mass planet placed in orbit at 25 AU within a 0.14 M{sub sun} disk. The disk spans 5-40 AU around a 1 M{sub sun} star and is initially marginally unstable. In one simulation, the planet is inserted prior to the eruption of GIs; in another, it is inserted only after the disk has settled into a quasi-steady GI-active state, where heating by GIs roughly balances radiative cooling. When the planet is present from the beginning, its own wake stimulates growth of a particular global mode with which it strongly interacts, and the planet plunges inward 6 AU in about 10{sup 3} years. In both cases with embedded planets, there are times when the planet's radial motion is slow and varies in direction. At other times, when the planet appears to be interacting with strong spiral modes, migration both inward and outward can be relatively rapid, covering several AUs over hundreds of years. Migration in both cases appears to stall near the inner Lindblad resonance of a dominant low-order mode. Planet orbit eccentricities fluctuate rapidly between about 0.02 and 0.1 throughout the GI-active phases of the simulations.

Michael, Scott; Durisen, Richard H. [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Boley, Aaron C., E-mail: scamicha@indiana.edu, E-mail: durisen@astro.indiana.edu, E-mail: aaron.boley@gmail.com [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States)

2011-08-20T23:59:59.000Z

399

Monopole gravitational waves from relativistic fireballs driving gamma-ray bursts  

E-Print Network (OSTI)

Einstein's general relativity predicts that pressure, in general stresses, play a similar role to energy density in generating gravity. The source of gravitational field, the active gravitational mass density, sometimes referred to as Whittaker's mass density, is not conserved, hence its changes can propagate as monopole gravitational waves. Such waves can be generated only by astrophysical sources with varying gravitational mass. Here we show that relativistic fireballs, considered in modelling gamma-ray burst phenomena, are likely to radiate monopole gravitational waves from high-pressure plasma with varying Whittaker's mass. Also, ejection of a significant amount of initial mass-energy of the progenitor contributes to the monopole gravitational radiation. We identify monopole waves with h^11+h^22 waves of Eddington's classification which propagate (in the z-direction) together with the energy carried by massless fields. We show that the monopole waves satisfy Einstein's equations, with a common stress-energy tensor for massless fields. The polarization mode of monopole waves is Phi_22, i.e. these are perpendicular waves which induce changes of the radius of a circle of test particles only (breathing mode). The astrophysical importance of monopole gravitational waves is discussed.

M. Kutschera

2003-09-16T23:59:59.000Z

400

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

E-Print Network (OSTI)

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.

Lee Samuel Finn; Badri Krishnan; Patrick J. Sutton

2003-04-11T23:59:59.000Z

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401

Swift Pointing and Gravitational-Wave Bursts from Gamma-Ray Burst Events  

E-Print Network (OSTI)

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. Even upper limits on the gravitational-wave strength associated with gamma-ray bursts could constrain the gamma-ray burst model. This 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 bursts 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.

Lee Samuel Finn; Badri Krishnan; Patrick J. Sutton

2003-04-23T23:59:59.000Z

402

Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Modules: Preprint  

Science Conference Proceedings (OSTI)

Concentrating photovoltaic (CPV) technology has recently gained interest based on their expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems use Fresnel lenses made of poly(methyl methacrylate)(PMMA) to obtain a high optical flux density. The optical and mechanical durability of such components, however, are not well established relative to the desired service life of 30 years. Specific reliability issues may include: reduced optical transmittance, discoloration, hazing, surface erosion, embrittlement, crack growth, physical aging, shape setting (warpage), and soiling. The initial results for contemporary lens- and material-specimens aged cumulatively to 6 months are presented. The study here uses an environmental chamber equipped with a xenon-arc lamp to age specimens at least 8x the nominal field rate. A broad range in the affected characteristics (including optical transmittance, yellowness index, mass loss, and contact angle) has been observed to date, depending on the formulation of PMMA used. The most affected specimens are further examined in terms of their visual appearance, surface roughness (examined via atomic force microscopy), and molecular structure (via Fourier transform infrared spectroscopy).

Miller, D. C.; Gedvilas, L. M.; To, B.; Kennedy, C. E.; Kurtz, S. R.

2010-08-01T23:59:59.000Z

403

Chaotic and Arnold stripes in weakly chaotic Hamiltonian systems  

E-Print Network (OSTI)

The dynamics in weakly chaotic Hamiltonian systems strongly depends on initial conditions and little can be affirmed about generic behaviors. Using two distinct Hamiltonian systems, namely one particle in an open rectangular billiard and four particles globally coupled on a discrete lattice, we show that in these models the transition from integrable motion to weak chaos emerges via chaotic stripes as the nonlinear parameter is increased. The stripes represent intervals of initial conditions which generate chaotic trajectories and increase with the nonlinear parameter of the system. In the billiard case the initial conditions are the injection angles. For higher-dimensional systems and small nonlinearities the chaotic stripes are the initial condition inside which Arnold diffusion occurs.

Marcelo S. Custódio; Cesar Manchein; Marcus W. Beims

2011-11-30T23:59:59.000Z

404

The structure of weak shocks in quantum plasmas  

E-Print Network (OSTI)

The structure of a weak shock in a quantum plasma is studied, taking into account both dissipation terms due to thermal conduction and dispersive quantum terms due to the Bohm potential. Unlike quantum systems without dissipations, even a small thermal conduction may lead to a stationary shock structure. In the limit of zero quantum effects, the monotonic Burgers solution for the weak shock is recovered. Still, even small quantum terms make the structure non-monotonic with the shock driving a train of oscillations into the initial plasma. The oscillations propagate together with the shock. The oscillations become stronger as the role of Bohm potential increases in comparison with thermal conduction. The results could be of importance for laser-plasma interactions, such as inertial confinement fusion plasmas, and in astrophysical environments, as well as in condensed matter systems.

Bychkov, Vitaly; Marklund, Mattias

2008-01-01T23:59:59.000Z

405

Compatibility of weak rigidity with some types of elastic schemes  

SciTech Connect

The behavior of the hypoelastic-Synge, hypoelastic-Maugin, and hypoelastic-Carter and Quintana almost-thermodynamic material schemes, under weak rigidity hypotheses, is studied. In every case, the absence of principal transverse shock waves (or the vanishing of the corresponding speeds) is obtained. The same result follows for the longitudinal shock waves when the Lame coefficient ..mu.. does not vanish. A definition of an elastic almost-thermodynamic material scheme based on the Fermi--Walker transport is proposed and compared with the above elastic schemes. The speeds of the principal shock waves associated are attained and its compatibility with the Ferrando--Olivert incompressibility condition is proved. In the presence of weak rigidity the elastic schemes here defined lead (assuming ..mu..not =0) to the Born-rigidity condition.

del Olmo, V.; Olivert, J.

1986-04-01T23:59:59.000Z

406

Weak localization of light in superdiffusive random systems  

E-Print Network (OSTI)

L\\'evy flights constitute a broad class of random walks that occur in many fields of research, from animal foraging in biology, to economy to geophysics. The recent advent of L\\'evy glasses allows to study L\\'evy flights in controlled way using light waves. This raises several questions about the influence of superdiffusion on optical interference effects like weak and strong localization. Super diffusive structures have the extraordinary property that all points are connected via direct jumps, meaning that finite-size effects become an essential part of the physical problem. Here we report on the experimental observation of weak localization in L\\'evy glasses and compare results with recently developed optical transport theory in the superdiffusive regime. Experimental results are in good agreement with theory and allow to unveil how light propagates inside a finite-size superdiffusive system.

Burresi, Matteo; Savo, Romolo; Bertolotti, Jacopo; Vynck, Kevin; Wiersma, Diederik S

2011-01-01T23:59:59.000Z

407

Bounds on Heavy-to-Heavy Weak Decay Form Factors  

E-Print Network (OSTI)

We provide upper and lower bounds on the semileptonic weak decay form factors for $B \\to D^(*)$ and $\\Lambda_b \\to \\Lambda_c$ decays by utilizing inclusive heavy quark effective theory sum rules. These bounds are calculated to second order in $\\Lambda_{QCD}/m_Q$ and first order in $\\alpha_s$. The $O(\\alpha_s^2 \\beta_0)$ corrections to the bounds at zero recoil are also presented.

Chiang, C W

2001-01-01T23:59:59.000Z

408

Bounds on Heavy-to-Heavy Weak Decay Form Factors  

E-Print Network (OSTI)

We provide upper and lower bounds on the semileptonic weak decay form factors for $B \\to D^(*)$ and $\\Lambda_b \\to \\Lambda_c$ decays by utilizing inclusive heavy quark effective theory sum rules. These bounds are calculated to second order in $\\Lambda_{QCD}/m_Q$ and first order in $\\alpha_s$. The $O(\\alpha_s^2 \\beta_0)$ corrections to the bounds at zero recoil are also presented.

Cheng-Wei Chiang

2000-09-18T23:59:59.000Z

409

Charge and Spin Transport in Superconducting Weak Links  

E-Print Network (OSTI)

Abstract. The coherent mixing of the current states in the superconducting weak link subject to a Josephson phase difference ? and subject to an external transport current in the banks is one of the aims of this work. At ? = ? the nonlocal mixing of current states produces two vortices close to the point-contact between superconducting bulks. The effect of point-contact reflection in an impenetrable interface and effect of temperature on the vortices have been studied. It is obtained that increasing the reflection of the point-contact destroys the vortices while increasing the temperature restore these vortices. The vortex state is a new version of the interference between the macroscopic states and quantum tunnelling. Also, the weak link between unitary triplet superconductors which have f?wave and p + h?wave pairing symmetry has been studied from the spin and charge current-phase relation point of view. The main result in the second part of this thesis, is the polarization of the spin transport when a junction between triplet superconductors is used. It is observed that the spin current is the result of the misorientation between the gap vectors of two supercondcutors. In addition, the weak link between two bipolar nonunitary triplet superconductors is studied mathematically. The current-phase relations obtained in third part of this thesis are totally different from the junctions between the unitary spin-triplet superconductors and between the spin-singlet superconductors. The current phase diagrams which have been obtained in this work can be used to distinguish the symmetry of the order parameter in the crystals. PACS numbers: 74.50.+r, 74.20.Rp, 72.25.-b, 74.70.Pq, 74.70.TxCharge and Spin Transport in Superconducting Weak Links 2 1.

Gholamreza Rashedi

2005-01-01T23:59:59.000Z

410

An F-statistic based multi-detector veto for detector artifacts in continuous-wave gravitational wave data  

E-Print Network (OSTI)

Continuous gravitational waves (CW) are expected from spinning neutron stars with non-axisymmetric deformations. A network of interferometric detectors (LIGO, Virgo and GEO600) is looking for these signals. They are predicted to be very weak and retrievable only by integration over long observation times. One of the standard methods of CW data analysis is the multi-detector F-statistic. In a typical search, the F-statistic is computed over a range in frequency, spin-down and sky position, and the candidates with highest F values are kept for further analysis. However, this detection statistic is susceptible to a class of noise artifacts, strong monochromatic lines in a single detector. By assuming an extended noise model - standard Gaussian noise plus single-detector lines - we can use a Bayesian odds ratio to derive a generalized detection statistic, the line veto (LV-) statistic. In the absence of lines, it behaves similarly to the F-statistic, but it is more robust against line artifacts. In the past, ad-h...

Keitel, David; Papa, Maria Alessandra; Siddiqi, Maham

2012-01-01T23:59:59.000Z

411

An F-statistic based multi-detector veto for detector artifacts in continuous-wave gravitational wave data  

E-Print Network (OSTI)

Continuous gravitational waves (CW) are expected from spinning neutron stars with non-axisymmetric deformations. A network of interferometric detectors (LIGO, Virgo and GEO600) is looking for these signals. They are predicted to be very weak and retrievable only by integration over long observation times. One of the standard methods of CW data analysis is the multi-detector F-statistic. In a typical search, the F-statistic is computed over a range in frequency, spin-down and sky position, and the candidates with highest F values are kept for further analysis. However, this detection statistic is susceptible to a class of noise artifacts, strong monochromatic lines in a single detector. By assuming an extended noise model - standard Gaussian noise plus single-detector lines - we can use a Bayesian odds ratio to derive a generalized detection statistic, the line veto (LV-) statistic. In the absence of lines, it behaves similarly to the F-statistic, but it is more robust against line artifacts. In the past, ad-hoc post-processing vetoes have been implemented in searches to remove these artifacts. Here we provide a systematic framework to develop and benchmark this class of vetoes. We present our results from testing this LV-statistic on simulated data.

David Keitel; Reinhard Prix; Maria Alessandra Papa; Maham Siddiqi

2012-01-25T23:59:59.000Z

412

First Determination of the Weak Charge of the Proton  

E-Print Network (OSTI)

The Qweak experiment has measured the parity-violating asymmetry in polarized e-p elastic scattering at Q^2 = 0.025(GeV/c)^2, employing 145 microamps of 89% longitudinally polarized electrons on a 34.4cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run are reported here, constituting approximately 4% of the data collected in the experiment. From these initial results the measured asymmetry is Aep = -279 +- 35 (statistics) +- 31 (systematics) ppb, which is the smallest and most precise asymmetry ever measured in polarized e-p scattering. The small Q^2 of this experiment has made possible the first determination of the weak charge of the proton, QpW, by incorporating earlier parity-violating electron scattering (PVES) data at higher Q^2 to constrain hadronic corrections. The value of QpW obtained in this way is QpW(PVES) = 0.064 +- 0.012, in good agreement with the Standard Model prediction of QpW(SM) = 0.0710 +- 0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be QnW(PVES+APV) = -0.975 +- 0.010.

Qweak Collaboration; D. Androic; D. S. Armstrong; A. Asaturyan; T. Averett; J. Balewski; J. Beaufait; R. S. Beminiwattha; J. Benesch; F. Benmokhtar; J. Birchall; R. D. Carlini; G. D. Cates; J. C. Cornejo; S. Covrig; M. M. Dalton; C. A. Davis; W. Deconinck; J. Diefenbach; J. F. Dowd; J. A. Dunne; D. Dutta; W. S. Duvall; M. Elaasar; W. R. Falk; J. M. Finn; T. Forest; D. Gaskell; M. T. W. Gericke; J. Grames; V. M. Gray; K. Grimm; F. Guo; J. R. Hoskins; K. Johnston; D. Jones; M. Jones; R. Jones; M. Kargiantoulakis; P. M. King; E. Korkmaz; S. Kowalski; J. Leacock; J. Leckey; A. R. Lee; J. H. Lee; L. Lee; S. MacEwan; D. Mack; J. A. Magee; R. Mahurin; J. Mammei; J. W. Martin; M. J. McHugh; D. Meekins; J. Mei; R. Michaels; A. Micherdzinska; A. Mkrtchyan; H. Mkrtchyan; N. Morgan; K. E. Myers; A. Narayan; L. Z. Ndukum; V. Nelyubin; Nuruzzaman; W. T. H van Oers; A. K. Opper; S. A. Page; J. Pan; K. D. Paschke; S. K. Phillips; M. L. Pitt; M. Poelker; J. F. Rajotte; W. D. Ramsay; J. Roche; B. Sawatzky; T. Seva; M. H. Shabestari; R. Silwal; N. Simicevic; G. R. Smith; P. Solvignon; D. T. Spayde; A. Subedi; R. Subedi; R. Suleiman; V. Tadevosyan; W. A. Tobias; V. Tvaskis; B. Waidyawansa; P. Wang; S. P. Wells; S. A. Wood; S. Yang; R. D. Young; S. Zhamkochyan

2013-07-19T23:59:59.000Z

413

$?$ meson exchange effect on nonmesonic hypernuclear weak decay observables  

E-Print Network (OSTI)

We analyze the influence of $\\sigma$ meson exchange on the main nonmesonic hypernuclear weak decay observables: the total rate, $\\Gamma_{NM}$, the neutron-to-proton branching ratio, $\\Gamma_{n/p}$, and the proton asymmetry parameter, $a_\\Lambda$. The $\\sigma$ meson exchange is added to the standard strangeness-changing weak $\\Lambda N\\to NN$ transition potential, which includes the exchange of the complete pseudoscalar and vector mesons octet ($\\pi$, $\\eta$, $K$, $\\rho$, $\\omega$, $K^*$). Using a shell model formalism, the $\\sigma$ meson weak coupling constants are adjusted to reproduce the recent $\\Gamma_{NM}$ and $\\Gamma_{n/p}$ experimental data for $^5_{\\Lambda}He$. Numerical results for the remaining observables of $^5_{\\Lambda}He$ and all the observables of $^{12}_{\\Lambda}C$ decays are presented. They clearly show that the addition of the $\\sigma$ meson, in spite of improving some observables values, is not enough to reproduce simultaneously all the measurements, and the puzzle posed by the experimental data remains unexplained.

C. Barbero; A. Mariano

2005-09-15T23:59:59.000Z

414

First Determination of the Weak Charge of the Proton  

SciTech Connect

The Qweak experiment has measured the parity-violating asymmetry in polarized e-p elastic scattering at Q^2 = 0.025(GeV/c)^2, employing 145 microamps of 89% longitudinally polarized electrons on a 34.4cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run are reported here, constituting approximately 4% of the data collected in the experiment. From these initial results the measured asymmetry is A_e_p = -279 +- 35 (statistics) +- 31 (systematics) ppb, which is the smallest and most precise asymmetry ever measured in polarized e-p scattering. The small Q^2 of this experiment has made possible the first determination of the weak charge of the proton, Q^p_W, by incorporating earlier parity-violating electron scattering (PVES) data at higher Q^2 to constrain hadronic corrections. The value of Q^p_W obtained in this way is Q^p_W(PVES) = 0.064 +- 0.012, in good agreement with the Standard Model prediction of Q^p_W(SM) = 0.0710 +- 0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q^n_W(PVES+APV) = -0.975 +- 0.010.

Androic, D; Armstrong, D S; Asaturyan, A; Averett, T; Balewski, J; Beaufait, J; Beminiwattha, R S; Benesch, J; Benmokhtar, F; Birchall, J; Carlini, R D [JLAB; Cates, G D; Cornejo, J C; Covrig, S; Dalton, M M; Davis, C A; Deconinck, W; Diefenbach, J; Dowd, J F; Dunne, J A; Dutta, D; Duvall, W S; Elaasar, M; Falk, W R; Finn, J M; Forest, T; Gaskell, D; Gericke, M T. W.; Grames, J; Gray, V M; Grimm, K; Guo, F; Hoskins, J R; Johnston, K; Jones, D; Jones, M; Jones, R; Kargiantoulakis, M; King, P M; Korkmaz, E; Kowalski, S; Leacock, J; Leckey, J; Lee, A R; Lee, J H; Lee, L; MacEwan, S; Mack, D; Magee, J A; Mahurin, R; Mammei, J; Martin, J W; McHugh, M J; Meekins, D; Mei, J; Michaels, R; Micherdzinska, A; Mkrtchyan, A; Mkrtchyan, H; Morgan, N; Myers, K E; Narayan, A; Ndukum, L Z; Nelyubin, V; van Oers, W T H; Nuruzzaman,; Opper, A K; Page, S A; Pan, J; Paschke, K D; Phillips, S K; Pitt, M L; Poelker, M; Rajotte, J F; Ramsay, W D; Roche, J; Sawatzky, B; Seva, T; Shabestari, M H; Silwal, R; Simicevic, N; Smith, G R; Solvignon, P; Spayde, D T; Subedi, A; Subedi, R; Suleiman, R; Tadevosyan, V; Tobias, W A; Tvaskis, V; Waidyawansa, B; Wang, P; Wells, S P; Wood, S A; Yang, S; Young, R D; Zhamkochyan, S

2013-10-01T23:59:59.000Z

415

TYPE III RADIO BURSTS PERTURBED BY WEAK CORONAL SHOCKS  

Science Conference Proceedings (OSTI)

Some type III bursts are observed to undergo sudden flux modifications, e.g., reductions and intensifications, when type III beams cross shocks in the upper corona or solar wind. First simulations are presented for type III bursts perturbed by weak coronal shocks, which type III beams traverse. The simulations incorporate spatially localized jumps in plasma density and electron and ion temperatures downstream of a shock. A shock is predicted to produce significant modulations to a type III burst: (1) a broadband flux reduction or frequency gap caused by the shock's density jump, (2) a narrowband flux intensification originating from where the downstream plasma density locally has a small gradient, (3) a possible intensification from the shock front or just upstream, and (4) changes in the frequency drift rate profile and the temporal evolution of radiation flux at frequencies corresponding to the shocked plasma. The modulations are caused primarily by fundamental modifications to the radiation processes in response to the shocked density and temperatures. The predicted intensifications and reductions appear qualitatively consistent with the available small number of reported observations, although it is unclear how representative these observations are. It is demonstrated that a weak shock can cause an otherwise radio-quiet type III beam to produce observable levels of narrowband radio emission. The simulations suggest that type III bursts with frequency-time fine structures may provide a tool to probe shocks in the corona and solar wind, especially for weak shocks that do not radiate by themselves.

Li, B.; Cairns, Iver H. [School of Physics, University of Sydney, New South Wales 2006 (Australia)

2012-07-10T23:59:59.000Z

416

Spectral multiplicity for powers of weakly mixing automorphisms  

SciTech Connect

We study the behaviour of the maximal spectral multiplicity m(R{sup n}) for the powers of a weakly mixing automorphism R. For some particular infinite sets A we show that there exists a weakly mixing rank-one automorphism R such that m(R{sup n})=n and m(R{sup n+1})=1 for all positive integers n element of A. Moreover, the cardinality cardm(R{sup n}) of the set of spectral multiplicities for the power R{sup n} is shown to satisfy the conditions cardm(R{sup n+1})=1 and cardm(R{sup n})=2{sup m(n)}, m(n){yields}{infinity}, n element of A. We also construct another weakly mixing automorphism R with the following properties: all powers R{sup n} have homogeneous spectra and the set of limit points of the sequence {l_brace}m(R{sup n})/n:n element of N{r_brace} is infinite. Bibliography: 17 titles.

Ryzhikov, Valerii V [M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow (Russian Federation)

2012-07-31T23:59:59.000Z

417

First LIGO search for gravitational wave bursts from cosmic (super)strings  

Science Conference Proceedings (OSTI)

We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected in 14.9 days of data from times when all three LIGO detectors were operating. We interpret the result in terms of a frequentist upper limit on the rate of gravitational wave bursts and use the limits on the rate to constrain the parameter space (string tension, reconnection probability, and loop sizes) of cosmic string models. Many grand unified theory-scale models (with string tension G{mu}/c{sup 2}{approx_equal}10{sup -6}) can be ruled out at 90% confidence for reconnection probabilities p{<=}10{sup -3} if loop sizes are set by gravitational back reaction.

Abbott, B. P.; Abbott, R.; Adhikari, R.; Anderson, S. B.; Araya, M.; Armandula, H.; Aso, Y.; Ballmer, S.; Barton, M. A.; Betzwieser, J.; Billingsley, G.; Black, E.; Blackburn, J. K.; Bork, R.; Boschi, V.; Brooks, A. F.; Cannon, K. C.; Cardenas, L.; Cepeda, C.; Chalermsongsak, T. [LIGO-California Institute of Technology, Pasadena, California 91125 (United States)] (and others)

2009-09-15T23:59:59.000Z

418

Gravitational Potential Energy Balance for the Thermal Circulation in a Model Ocean  

Science Conference Proceedings (OSTI)

The gravitational potential energy balance of the thermal circulation in a simple rectangular model basin is diagnosed from numerical experiments based on a mass-conserving oceanic general circulation model. The vertical mixing coefficient is ...

Rui Xin Huang; Xingze Jin

2006-07-01T23:59:59.000Z

419

Directional Limits on Persistent Gravitational Waves Using LIGO S5 Science Data  

E-Print Network (OSTI)

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for ...

Barnum, Sam

420

Development of techniques for quantum-enhanced laser-interferometric gravitational-wave detectors  

E-Print Network (OSTI)

A detailed theoretical and experimental study of techniques necessary for quantum-enhanced laser- interferometric gravitational wave (GW) detectors was carried out. The basic theory of GWs and laser-interferometric GW ...

Goda, Keisuke

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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421

Searches for Gravitational Waves from Compact Binary Coalescences with the LIGO and Virgo Detectors  

Science Conference Proceedings (OSTI)

Among the most promising sources of gravitational waves for ground?based detectors are the signals emitted during the coalescence of compact binary systems containing neutron stars or black holes. In recent years

F. Marion; The LIGO Scientific Collaboration; The Virgo Collaboration

2010-01-01T23:59:59.000Z

422

EXPLORING SHORT GAMMA-RAY BURSTS AS GRAVITATIONAL-WAVE STANDARD SIRENS  

E-Print Network (OSTI)

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 ...

Hughes, Scott A

423

Novel approaches to Newtonian noise suppression in interferometric gravitational wave detection  

E-Print Network (OSTI)

The Laser Interferometer Gravitational-wave Observatory (LIGO) attempts to detect ripples in the curvature of spacetime using two large scale interferometers. These detectors are several kilometer long Michelson interferometers ...

Hunter-Jones, Nicholas R

2011-01-01T23:59:59.000Z

424

X-Pipeline: an analysis package for autonomous gravitational-wave burst searches  

E-Print Network (OSTI)

Autonomous gravitational-wave searches—fully automated analyses of data that run without human intervention or assistance—are desirable for a number of reasons. They are necessary for the rapid identification of ...

Sutton, Patrick J.

425

Gravitational fields with sources, regular black holes, quasiblack holes, and analogue black holes  

E-Print Network (OSTI)

We discuss recent developments in gravitational fields with sources, regular black holes, quasiblack holes, and analogue black holes, related to the talks presented at the corresponding Parallel Session AT3 of the 13th Marcel Grossmann Meeting.

Lemos, José P S

2013-01-01T23:59:59.000Z

426

Can observations inside the Solar System reveal the gravitational properties of the quantum vacuum?  

E-Print Network (OSTI)

The understanding of the gravitational properties of the quantum vacuum might be the next scientific revolution.It was recently proposed that the quantum vacuum contains the virtual gravitational dipoles; we argue that this hypothesis might be tested within the Solar System. The key point is that quantum vacuum ("enriched" with the gravitational dipoles) induces a retrograde precession of the perihelion. It is obvious that this phenomenon might eventually be revealed by more accurate studies of orbits of planets and orbits of the artificial Earth satellites. However, we suggest that potentialy the best "laboratory" for the study of the gravitational properties of the quantum vacuum is the Dwarf Planet Eris and its satellite Dysnomia; the distance of nearly 100AU makes it the unique system in which the precession of the perihelion of Dysnomia (around Eris) is strongly dominated by the quantum vacuum.

Dragan Slavkov Hajdukovic

2012-10-28T23:59:59.000Z

427

Gravitational wave generation from bubble collisions in first-order phase transitions: an analytic approach  

E-Print Network (OSTI)

Gravitational wave production from bubble collisions was calculated in the early nineties using numerical simulations. In this paper, we present an alternative analytic estimate, relying on a different treatment of stochasticity. In our approach, we provide a model for the bubble velocity power spectrum, suitable for both detonations and deflagrations. From this, we derive the anisotropic stress and analytically solve the gravitational wave equation. We provide analytical formulae for the peak frequency and the shape of the spectrum which we compare with numerical estimates. In contrast to the previous analysis, we do not work in the envelope approximation. This paper focuses on a particular source of gravitational waves from phase transitions. In a companion article, we will add together the different sources of gravitational wave signals from phase transitions: bubble collisions, turbulence and magnetic fields and discuss the prospects for probing the electroweak phase transition at LISA.

Caprini, Chiara; Servant, Géraldine

2008-01-01T23:59:59.000Z

428

Gravitational wave generation from bubble collisions in first-order phase transitions: an analytic approach  

E-Print Network (OSTI)

Gravitational wave production from bubble collisions was calculated in the early nineties using numerical simulations. In this paper, we present an alternative analytic estimate, relying on a different treatment of stochasticity. In our approach, we provide a model for the bubble velocity power spectrum, suitable for both detonations and deflagrations. From this, we derive the anisotropic stress and analytically solve the gravitational wave equation. We provide analytical formulae for the peak frequency and the shape of the spectrum which we compare with numerical estimates. In contrast to the previous analysis, we do not work in the envelope approximation. This paper focuses on a particular source of gravitational waves from phase transitions. In a companion article, we will add together the different sources of gravitational wave signals from phase transitions: bubble collisions, turbulence and magnetic fields and discuss the prospects for probing the electroweak phase transition at LISA.

Chiara Caprini; Ruth Durrer; Geraldine Servant

2007-11-16T23:59:59.000Z

429

Prospects for Localization of Gravitational Wave Transients by the Advanced LIGO and Advanced Virgo Observatories  

E-Print Network (OSTI)

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. For concreteness, we focus primarily on gravitational-wave signals from the inspiral of binary neutron star (BNS) systems, as the source considered likely to be the most common for detection and also promising for multimessenger astronomy. We find that confident detections will likely require at least 2 detectors operating with BNS sensitive ranges of at least 100 Mpc, while ranges approaching 200 Mpc should give at least ~1 BNS detection per year even under pessimistic predictions of signal rates. The ability to localize the source of the detected signals...

Aasi, J; Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M; Accadia, T; Acernese, F; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aguiar, O D; Ajith, P; Allen, B; Allocca, A; Ceron, E Amador; Amariutei, D; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Ast, S; Aston, S M; Astone, P; Atkinson, D; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P; Ballardin, G; Ballmer, S; Bao, Y; Barayoga, J C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Bastarrika, M; Basti, A; Batch, J; Bauchrowitz, J; Bauer, Th S; Bebronne, M; Behnke, B; Bejger, M; Beker, M G; Bell, A S; Bell, C; Bergmann, G; Berliner, J M; Bertolini, A; Betzwieser, J; Beveridge, N; Beyersdorf, P T; Bhadbade, T; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bland, B; Blom, M; Bock, O; Bodiya, T P; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, S; Bosi, L; Bouhou, B; Bowers, J; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Breyer, J; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Brown, D D; Brueckner, F; Buckland, K; Bulik, T; Bulten, H J; Buonanno, A; Burguet-Castell, J; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Calloni, E; Camp, J B; Campsie, P; Cannon, K; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A D; Caudill, S; Cavagliŕ, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chalermsongsak, T; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, C T Y; Ciani, G; Clara, F; Clark, D E; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colacino, C N; Colla, A; Colombini, M; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corsi, A; Costa, C A; Coughlin, M; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Craig, K; Creighton, J D E; Creighton, T D; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Dayanga, T; De Rosa, R; Debreczeni, G; Degallaix, J; Del Pozzo, W; Deleeuw, E; Denker, T; Dent, T; Dergachev, V; DeRosa, R; DeSalvo, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Díaz, M; Dietz, A; Donovan, F; Dooley, K L; Doravari, S; Drago, M; Drasco, S; Drever, R W P; Driggers, J C; Du, Z; Dumas, J -C; Dwyer, S; Eberle, T; Edwards, M; Effler, A; Ehrens, P; Eikenberry, S S; Endröczi, G; Engel, R; Essick, R; Etzel, T; Evans, K; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farr, B F; Farr, W; Favata, M; Fazi, D; Fehrmann, H; Feldbaum, D; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Foley, S; Forsi, E; Forte, L A; Fotopoulos, N; Fournier, J -D; Franc, J; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, M A; Frei, Z; Freise, A; Frey, R; Fricke, T T; Friedrich, D; Fritschel, P; Frolov, V V; Fujimoto, M -K; Fulda, P J; Fyffe, M; Gair, J; Galimberti, M; Gammaitoni, L; Garcia, J; Garufi, F; Gáspár, M E; Gehrels, N; Gelencser, G; Gemme, G; Genin, E; Gennai, A; Gergely, L Á; Ghosh, S; Giaime, J A; Giampanis, S; Giardina, K D; Giazotto, A; Gil-Casanova, S; Gill, C; Gleason, J; Goetz, E; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Griffo, C; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C; Gustafson, E K; Gustafson, R; Hammer, D; Hammond, G; Hanks, J; Hanna, C; Hanson, J; Haris, K; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hartman, M T; Haughian, K; Hayama, K; Heefner, J; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M A; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Holtrop, M; Hong, T; Hooper, S; Hough, J; Howell, E J; Huang, V; Huerta, E A; Hughey, B; Huttner, S H; Huynh, M; Huynh-Dinh, T; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jang, Y J; Jaranowski, P; Jesse, E; Johnson, W W; Jones, D; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kasprzack, M; Kasturi, R; Katsavounidis, E; Katzman, W; Kaufer, H; Kawabe, K; Kawamura, S; Kawazoe, F; Keitel, D; Kelley, D; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, B K; Kim, C; Kim, K; Kim, N; Kim, Y M; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D; Kozameh, C; Kremin, A

2013-01-01T23:59:59.000Z