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1

Weak gravitational lensing with the Square Kilometre Array  

E-Print Network [OSTI]

We investigate the capabilities of various stages of the SKA to perform world-leading weak gravitational lensing surveys. We outline a way forward to develop the tools needed for pursuing weak lensing in the radio band. We identify the key analysis challenges and the key pathfinder experiments that will allow us to address them in the run up to the SKA. We identify and summarize the unique and potentially very powerful aspects of radio weak lensing surveys, facilitated by the SKA, that can solve major challenges in the field of weak lensing. These include the use of polarization and rotational velocity information to control intrinsic alignments, and the new area of weak lensing using intensity mapping experiments. We show how the SKA lensing surveys will both complement and enhance corresponding efforts in the optical wavebands through cross-correlation techniques and by way of extending the reach of weak lensing to high redshift.

Brown, M L; Camera, S; Harrison, I; Joachimi, B; Metcalf, R B; Pourtsidou, A; Takahashi, K; Zuntz, J A; Abdalla, F B; Bridle, S; Jarvis, M; Kitching, T D; Miller, L; Patel, P

2015-01-01T23:59:59.000Z

2

Atomic Inference from Weak Gravitational Lensing Data  

SciTech Connect (OSTI)

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

3

Constraining dark energy from the abundance of weak gravitational lenses  

E-Print Network [OSTI]

We examine the prospect of using the observed abundance of weak gravitational lenses to constrain the equation-of-state parameter w of the dark energy. Here we solve the spherical-collapse model with dark energy, clarifying some ambiguities found in the literature, and provide fitting formulas for the overdensity at virialization and the linear-theory overdensity at collapse. We then compute the variation in the predicted weak-lens abundance with w. We find that the predicted redshift distribution and number count of weak lenses are highly degenerate in w and \\Omega_0. If we fix \\Omega_0 the number count for w=-2/3 is a factor of 2 smaller than for the \\LambdaCDM model. However, if we allow \\Omega_0 to vary with w such that the amplitude of the matter power spectrum as measured by COBE matches that obtained from the X-ray cluster abundance, the decrease in the predicted lens abundance is less than 25% for -1 40 degree^2 in order for the number count to differentiate a \\LambdaCDM cosmology from a w=-0.9 model...

Weinberg, N N; Weinberg, Nevin N.; Kamionkowski, Marc

2003-01-01T23:59:59.000Z

4

Statistical properties of the convergence due to weak gravitational lensing by non-linear structures  

E-Print Network [OSTI]

Density fluctuations in the matter distribution lead to distortions of the images of distant galaxies through weak gravitational lensing effects. This provides an efficient probe of the cosmological parameters and of the density field. In this article, we investigate the statistical properties of the convergence due to weak gravitational lensing by non-linear structures (i.e. we consider small angular windows $\\theta \\la 1'$). Previous studies have shown how to relate the second and third order moments of the convergence to those of the density contrast while models based on the Press-Schechter prescription provide an estimate of the tail of $P(\\kappa)$. Here we present a method to obtain an estimate of the full p.d.f. of the convergence $P(\\kappa)$. It is based on a realistic description of the density field which applies to overdense as well as underdense regions. We show that our predictions agree very well with the results of N-body simulations for the convergence. This could allow one to derive the cosmological parameters $(\\Omega_m,\\Omega_{\\Lambda})$ as well as the full p.d.f. $P(\\delta_R)$ of the density contrast itself in the non-linear regime from observations. Hence this gives a very powerfull tool to constrain scenarios of structure formation.

P. Valageas

2000-05-12T23:59:59.000Z

5

Gravitational lensing by spinning and escaping lenses  

E-Print Network [OSTI]

The effect of currents of mass on bending of light rays is considered in the weak field regime. Following Fermat's principle and the standard theory of gravitational lensing, we derive the gravitomagnetic correction to time delay function and deflection angle caused by a geometrically-thin lens. The cases of both rotating and shifting deflectors are discussed.

M. Sereno

2003-05-12T23:59:59.000Z

6

GaBoDS: The Garching-Bonn Deep Survey -- II. Confirmation of EIS cluster candidates by weak gravitational lensing  

E-Print Network [OSTI]

We report the first confirmation of colour-selected galaxy cluster candidates by means of weak gravitational lensing. Significant lensing signals were identified in the course of the shear-selection programme of dark matter haloes in the Garching-Bonn Deep Survey, which currently covers 20 square degrees of deep, high-quality imaging data on the southern sky. The detection was made in a field that was previously covered by the ESO Imaging Survey (EIS) in 1997. A highly significant shear-selected mass-concentration perfectly coincides with the richest EIS cluster candidate at z~0.2, thus confirming its cluster nature. Several other shear patterns in the field can also be identified with cluster candidates, one of which could possibly be part of a filament at z~0.45.

Mischa Schirmer; Thomas Erben; Peter Schneider; Christian Wolf; Klaus Meisenheimer

2004-01-12T23:59:59.000Z

7

What is Gravitational Lensing?  

ScienceCinema (OSTI)

July 28, 2009 Berkeley Lab summer lecture: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

Alexie Leauthaud and Reiko Nakajima

2010-01-08T23:59:59.000Z

8

Weak Lensing Simulations for the SKA  

E-Print Network [OSTI]

Weak gravitational lensing measurements are traditionally made at optical wavelengths where many highly resolved galaxy images are readily available. However, the Square Kilometre Array (SKA) holds great promise for this type of measurement at radio wavelengths owing to its greatly increased sensitivity and resolution over typical radio surveys. The key to successful weak lensing experiments is in measuring the shapes of detected sources to high accuracy. In this document we describe a simulation pipeline designed to simulate radio images of the quality required for weak lensing, and will be typical of SKA observations. We provide as input, images with realistic galaxy shapes which are then simulated to produce images as they would have been observed with a given radio interferometer. We exploit this pipeline to investigate various stages of a weak lensing experiment in order to better understand the effects that may impact shape measurement. We first show how the proposed SKA1-Mid array configurations perfor...

Patel, Prina; Makhathini, Sphesihle; Abdalla, Filipe; Bacon, David; Brown, Michael L; Heywood, Ian; Jarvis, Matt; Smirnov, Oleg

2015-01-01T23:59:59.000Z

9

Gravitational lensing by stars with angular momentum  

E-Print Network [OSTI]

Gravitational lensing by spinning stars, approximated as homogeneous spheres, is discussed in the weak field limit. Dragging of inertial frames, induced by angular momentum of the deflector, breaks spherical symmetry. I examine how the gravito-magnetic field affects image positions, caustics and critical curves. Distortion in microlensing-induced light curves is also considered.

M. Sereno

2003-07-11T23:59:59.000Z

10

Weak Lensing Detection in CMB Maps  

E-Print Network [OSTI]

The weak lensing effects are known to change only weakly the shape of the power spectrum of the Cosmic Microwave Background (CMB) temperature fluctuations. I show here that they nonetheless induce specific non-Gaussian effects that can be detectable with the four-point correlation function of the CMB anisotropies. The magnitude and geometrical dependences of this correlation function are investigated in detail. It is thus found to scale as the square of the derivative of the two-point correlation function and as the angular correlation function of the gravitational displacement field. It also contains specific dependences on the shape of the quadrangle formed by the four directions. When averaged at a given scale, the four-point function, that identifies with the connected part of the fourth moment of the probability distribution function of the local filtered temperature, scales as the square of logarithmic slope of its second moment, and as the variance of the gravitational magnification at the same angular scale. All these effects have been computed for specific cosmological models. It is worth noting that, as the amplitude of the gravitational lens effects has a specific dependence on the cosmological parameters, the detection of the four-point correlation function could provide precious complementary constraints to those brought by the temperature power spectrum.

F. Bernardeau

1997-03-05T23:59:59.000Z

11

Lossy compression of weak lensing data  

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

Future orbiting observatories will survey large areas of sky in order to constrain the physics of dark matter and dark energy using weak gravitational lensing and other methods. Lossy compression of the resultant data will improve the cost and feasibility of transmitting the images through the space communication network. We evaluate the consequences of the lossy compression algorithm of Bernstein et al. (2010) for the high-precision measurement of weak-lensing galaxy ellipticities. This square-root algorithm compresses each pixel independently, and the information discarded is by construction less than the Poisson error from photon shot noise. For simulated space-based images (without cosmic rays) digitized to the typical 16 bits per pixel, application of the lossy compression followed by image-wise lossless compression yields images with only 2.4 bits per pixel, a factor of 6.7 compression. We demonstrate that this compression introduces no bias in the sky background. The compression introduces a small amount of additional digitization noise to the images, and we demonstrate a corresponding small increase in ellipticity measurement noise. The ellipticity measurement method is biased by the addition of noise, so the additional digitization noise is expected to induce a multiplicative bias on the galaxies measured ellipticities. After correcting for this known noise-induced bias, we find a residual multiplicative ellipticity bias of m {approx} -4 x 10{sup -4}. This bias is small when compared to the many other issues that precision weak lensing surveys must confront, and furthermore we expect it to be reduced further with better calibration of ellipticity measurement methods.

Vanderveld, R Ali [Chicago U., EFI; Caltech /Caltech, JPL; Bernstein, Gary M [Pennsylvania U.; Stoughton, Chris [Fermilab; Rhodes, Jason [Caltech; Caltech, JPL; Massey, Richard [Royal Observ., Edinburgh; Dobke, Benjamin M [Caltech; Caltech, JPL

2011-06-01T23:59:59.000Z

12

A Computer Program to Visualize Gravitational Lenses  

E-Print Network [OSTI]

Gravitational lenses are presently playing an important role in astrophysics. By means of these lenses the parameters of the deflector such as its mass, ellipticity, etc. and Hubble's constant can be determined. Using C, Xforms, Mesa and Imlib a computer program to visualize this lens effect has been developed. This program has been applied to generate sequences of images of a source object and its corresponding images. It has also been used to visually test different models of gravitational lenses.

Francisco Frutos-Alfaro

2014-06-12T23:59:59.000Z

13

Magnified Weak Lensing Cross Correlation Tomography  

SciTech Connect (OSTI)

This project carried out a weak lensing tomography (WLT) measurement around rich clusters of galaxies. This project used ground based photometric redshift data combined with HST archived cluster images that provide the WLT and cluster mass modeling. The technique has already produced interesting results (Guennou et al, 2010,Astronomy & Astrophysics Vol 523, page 21, and Clowe et al, 2011 to be submitted). Guennou et al have validated that the necessary accuracy can be achieved with photometric redshifts for our purposes. Clowe et al titled "The DAFT/FADA survey. II. Tomographic weak lensing signal from 10 high redshift clusters," have shown that for the **first time** via this purely geometrical technique, which does not assume a standard rod or candle, that a cosmological constant is **required** for flat cosmologies. The intent of this project is not to produce the best constraint on the value of the dark energy equation of state, w. Rather, this project is to carry out a sustained effort of weak lensing tomography that will naturally feed into the near term Dark Energy Survey (DES) and to provide invaluable mass calibration for that project. These results will greatly advance a key cosmological method which will be applied to the top-rated ground-based project in the Astro2020 decadal survey, LSST. Weak lensing tomography is one of the key science drivers behind LSST. CO-I Clowe is on the weak lensing LSST committee, and senior scientist on this project, at FNAL James Annis, plays a leading role in the DES. This project has built on successful proposals to obtain ground-based imaging for the cluster sample. By 1 Jan, it is anticipated the project will have accumulated complete 5-color photometry on 30 (or about 1/3) of the targeted cluster sample (public webpage for the survey is available at http://cencos.oamp.fr/DAFT/ and has a current summary of the observational status of various clusters). In all, the project has now been awarded the equivalent of over 60 nights on 4-m class telescopes, which gives concrete evidence of strong community support for this project. The WLT technique is based on the dependence of the gravitational shear signal on the angular diameter distances between the observer, the lens, and the lensed galaxy to measure cosmological parameters. By taking the ratio of measured shears of galaxies with different redshifts around the same lens, one obtains a measurement of the ratios of the angular diameter distances involved. Making these observations over a large range of lenses and background galaxy redshifts will measure the history of the expansion rate of the universe. Because this is a purely geometric measurement, it is insensitive to any form of evolution of objects or the necessity to understand the physics in the early universe. Thus, WLT was identified by the Dark Energy Task Force as perhaps the best method to measure the evolution of DE. To date, however, the conjecture of the DETF has not been experimentally verified, but will be by the proposed project. The primary reason for the lack of tomography measurements is that one must have an exceptional data-set to attempt the measurement. One needs both extremely good seeing (or space observations) in order to minimize the point spread function smearing corrections on weak lensing shear measurements and deep, multi-color data, from B to z, to measure reliable photometric redshifts of the background galaxies being lensed (which are typically too faint to obtain spectroscopic redshifts). Because the entire process from multi-drizzling the HST images, and then creating shear maps, to gathering the necessary ground based observations, to generating photo-zs and then carrying out the tomography is a complicated task, until the creation of our team, nobody has taken the time to connect all the levels of expertise necessary to carry out this project based on HST archival data. Our data are being used in 2 Ph.D. theses. Kellen Murphy, at Ohio University, is using the tomography data along with simulations in a thesis expected to be completed in Jun

Ulmer, Melville P., Clowe, Douglas I.

2010-11-30T23:59:59.000Z

14

Weak Lensing: Dark Matter, Dark Energy  

SciTech Connect (OSTI)

The light rays from distant galaxies are deflected by massive structures along the line of sight, causing the galaxy images to be distorted. Measurements of these distortions, known as weak lensing, provide a way of measuring the distribution of dark matter as well as the spatial geometry of the universe. I will describe the ideas underlying this approach to cosmology. With planned large imaging surveys, weak lensing is a powerful probe of dark energy. I will discuss the observational challenges ahead and recent progress in developing multiple, complementary approaches to lensing measurements.

Jain, Bhuvnesh (University of Pennsylvania) [University of Pennsylvania

2006-02-27T23:59:59.000Z

15

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

16

EFFECT OF MASKED REGIONS ON WEAK-LENSING STATISTICS  

SciTech Connect (OSTI)

Sky masking is unavoidable in wide-field weak-lensing observations. We study how masks affect the measurement of statistics of matter distribution probed by weak gravitational lensing. We first use 1000 cosmological ray-tracing simulations to examine in detail the impact of masked regions on the weak-lensing Minkowski Functionals (MFs). We consider actual sky masks used for a Subaru Suprime-Cam imaging survey. The masks increase the variance of the convergence field and the expected values of the MFs are biased. The bias then compromises the non-Gaussian signals induced by the gravitational growth of structure. We then explore how masks affect cosmological parameter estimation. We calculate the cumulative signal-to-noise ratio (S/N) for masked maps to study the information content of lensing MFs. We show that the degradation of S/N for masked maps is mainly determined by the effective survey area. We also perform simple {chi}{sup 2} analysis to show the impact of lensing MF bias due to masked regions. Finally, we compare ray-tracing simulations with data from a Subaru 2 deg{sup 2} survey in order to address if the observed lensing MFs are consistent with those of the standard cosmology. The resulting {chi}{sup 2}/n{sub dof} = 29.6/30 for three combined MFs, obtained with the mask effects taken into account, suggests that the observational data are indeed consistent with the standard {Lambda}CDM model. We conclude that the lensing MFs are a powerful probe of cosmology only if mask effects are correctly taken into account.

Shirasaki, Masato; Yoshida, Naoki [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Hamana, Takashi, E-mail: masato.shirasaki@utap.phys.s.u-tokyo.ac.jp [National Astronomical Observatory of Japan, Tokyo 181-0015 (Japan)

2013-09-10T23:59:59.000Z

17

A toolbox for general elliptical gravitational lenses  

E-Print Network [OSTI]

We introduce a formalism to describe 2D-Potentials for 2D-matter (or charge) distributions with arbitrary elliptical symmetry including varying eccentricity and twisting of the iso-density curves. We use this approach to describe elliptical matter distributions such as elliptical galaxies or clusters as gravitational lenses. Figures are available upon request: tschramm@hs.uni-hamburg.de

T. Schramm

1993-11-09T23:59:59.000Z

18

Strong gravitational lensing of gravitational waves in Einstein Telescope  

SciTech Connect (OSTI)

Gravitational wave experiments have entered a new stage which gets us closer to the opening a new observational window on the Universe. In particular, the Einstein Telescope (ET) is designed to have a fantastic sensitivity that will provide with tens or hundreds of thousand NS-NS inspiral events per year up to the redshift z = 2. Some of such events should be gravitationally lensed by intervening galaxies. We explore the prospects of observing gravitationally lensed inspiral NS-NS events in the Einstein telescope. Being conservative we consider the lens population of elliptical galaxies. It turns out that depending on the local insipral rate ET should detect from one per decade detection in the pessimistic case to a tens of detections per year for the most optimistic case. The detection of gravitationally lensed source in gravitational wave detectors would be an invaluable source of information concerning cosmography, complementary to standard ones (like supernovae or BAO) independent of the local cosmic distance ladder calibrations.

Piórkowska, Aleksandra; Biesiada, Marek [Department of Astrophysics and Cosmology, Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Zhu, Zong-Hong, E-mail: aleksandra.piorkowska@us.edu.pl, E-mail: marek.biesiada@us.edu.pl, E-mail: zhuzh@bnu.edu.cn [Department of Astronomy, Beijing Normal University, Beijing 100875 (China)

2013-10-01T23:59:59.000Z

19

Wave optics and image formation in gravitational lensing  

E-Print Network [OSTI]

We discuss image formation in gravitational lensing systems using wave optics. Applying the Fresnel-Kirchhoff diffraction formula to waves scattered by a gravitational potential of a lens object, we demonstrate how images of source objects are obtained directly from wave functions without using a lens equation for gravitational lensing.

Yasusada Nambu

2012-07-30T23:59:59.000Z

20

Spurious Shear in Weak Lensing with LSST  

SciTech Connect (OSTI)

The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image {approx} 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to r {approx} 27.5, with over 4 billion well measured galaxies. To take full advantage of this unprecedented statistical power, the systematic errors associated with weak lensing measurements need to be controlled to a level similar to the statistical errors. This work is the first attempt to quantitatively estimate the absolute level and statistical properties of the systematic errors on weak lensing shear measurements due to the most important physical effects in the LSST system via high fidelity ray-tracing simulations. We identify and isolate the different sources of algorithm-independent, additive systematic errors on shear measurements for LSST and predict their impact on the final cosmic shear measurements using conventional weak lensing analysis techniques. We find that the main source of the errors comes from an inability to adequately characterise the atmospheric point spread function (PSF) due to its high frequency spatial variation on angular scales smaller than {approx} 10{prime} in the single short exposures, which propagates into a spurious shear correlation function at the 10{sup -4}-10{sup -3} level on these scales. With the large multi-epoch dataset that will be acquired by LSST, the stochastic errors average out, bringing the final spurious shear correlation function to a level very close to the statistical errors. Our results imply that the cosmological constraints from LSST will not be severely limited by these algorithm-independent, additive systematic effects.

Chang, C.; Kahn, S.M.; Jernigan, J.G.; Peterson, J.R.; AlSayyad, Y.; Ahmad, Z.; Bankert, J.; Bard, D.; Connolly, A.; Gibson, R.R.; Gilmore, K.; Grace, E.; Hannel, M.; Hodge, M.A.; Jee, M.J.; Jones, L.; Krughoff, S.; Lorenz, S.; Marshall, P.J.; Marshall, S.; Meert, A.

2012-09-19T23:59:59.000Z

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

Gravitational Aharonov-Bohm effect and gravitational lensing  

E-Print Network [OSTI]

Considering the spacetime around a rotating massif body it is seen that the time of flight of a light ray is different whether it travels on one side of the source or on the other. The difference is proportional to the angular momentum of the body. In the case that a compact rapidly rotating object is the source of a gravitational lensing effect, the contribution coming from the above mentioned gravitational Aharonov-Bohm effect should be added to the other causes of phase difference between light rays coming from different images of the same object.

A. Tartaglia

2000-03-08T23:59:59.000Z

22

Gravitational lensing in metric theories of gravity  

E-Print Network [OSTI]

Gravitational lensing in metric theories of gravity is discussed. I introduce a generalized approximate metric element, inclusive of both post-post-Newtonian (ppN) contributions and gravito-magnetic field. Following Fermat's principle and standard hyphoteses, I derive the time delay function and deflection angle caused by an isolated mass distribution. Several astrophysical systems are considered. In most of the cases, the gravito-magnetic correction offers the best perspectives for an observational detection. Actual measurements distinguish only marginally different metric theories one from another.

M. Sereno

2003-01-15T23:59:59.000Z

23

Neutrino halos in clusters of galaxies and their weak lensing signature  

SciTech Connect (OSTI)

We study whether non-linear gravitational effects of relic neutrinos on the development of clustering and large-scale structure may be observable by weak gravitational lensing. We compute the density profile of relic massive neutrinos in a spherical model of a cluster of galaxies, for several neutrino mass schemes and cluster masses. Relic neutrinos add a small perturbation to the mass profile, making it more extended in the outer parts. In principle, this non-linear neutrino perturbation is detectable in an all-sky weak lensing survey such as EUCLID by averaging the shear profile of a large fraction of the visible massive clusters in the universe, or from its signature in the general weak lensing power spectrum or its cross-spectrum with galaxies. However, correctly modeling the distribution of mass in baryons and cold dark matter and suppressing any systematic errors to the accuracy required for detecting this neutrino perturbation is severely challenging.

Villaescusa-Navarro, Francisco; Peña-Garay, Carlos [IFIC, Universidad de Valencia-CSIC, E-46071, Valencia (Spain); Miralda-Escudé, Jordi [Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys, 23, 08010-Barcelona (Spain); Quilis, Vicent, E-mail: villa@ific.uv.es, E-mail: miralda@icc.ub.es, E-mail: penya@ific.uv.es, E-mail: vicent.quilis@uv.es [Departamento de Astronomia y Astrofísica, Universidad de Valencia, C/ Dr. Moliner, 50, E-46100, Burjassot, Valencia (Spain)

2011-06-01T23:59:59.000Z

24

Constraints on warm dark matter from weak lensing in anomalous quadruple lenses  

E-Print Network [OSTI]

We investigate the weak lensing effect by line-of-sight structures with a surface mass density of solar mass/arcsec^2 in QSO-galaxy quadruple lens systems. Using high-resolution N-body simulations in warm dark matter (WDM) models and observed four quadruple lenses that show anomalies in the flux ratios, we obtain constraints on the mass of thermal WDM, m_WDM>= 1.3keV(95%CL) assuming that the density of the primary lens is described by a singular isothermal ellipsoid (SIE). The obtained constraint is consistent with those from Lyman-$\\alpha$ forests and the number counts of high-redshift galaxies at z>4. Our results show that WDM with a free-streaming comoving wavenumber k_{fs} <= 27 h/Mpc is disfavored as the major component of cosmological density at redshifts 0.5 <~ z <~ 4 provided that the SIE models describe the gravitational potentials of the primary lenses correctly.

Kaiki Taro Inoue; Ryuichi Takahashi; Tomo Takahashi; Tomoaki Ishiyama

2015-02-12T23:59:59.000Z

25

Weak Lensing Predictions at Intermediate Scales  

E-Print Network [OSTI]

As pointed out in previous studies, the measurement of the skewness of the convergence field $\\kappa$ will be useful in breaking the degeneracy among the cosmological parameters constrained from weak lensing observations. The combination of shot noise and finite survey volume implies that such a measurement is likely to be done in a range of intermediate scales ($0.5'$ to 20') where neither perturbation theory nor the hierarchical ansatz apply. Here we explore the behavior of the skewness of $\\kappa$ at these intermediate scales, based on results for the non-linear evolution of the mass bispectrum. We combined different ray-tracing simulations to test our predictions, and we find that our calculations describe accurately the transition from the weakly non-linear to the strongly non-linear regime. We show that the single lens-plane approximation remains accurate even in the non-linear regime, and we explicitly calculate the corrections to this approximation. We also discuss the prospects of measuring the skewn...

Van Waerbeke, L; Scoccimarro, R; Colombi, S; Bernardeau, F

2000-01-01T23:59:59.000Z

26

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

27

Gravitational lensing in eclipsing binary stars  

E-Print Network [OSTI]

I consider the effect of the gravitational deflection of light upon the light curves of eclipsing binary stars, focussing mainly upon systems containing at least one white dwarf component. In absolute terms the effects are small, however they are strongest at the time of secondary eclipse when the white dwarf transits its companion, and act to reduce the depth of this feature. If not accounted for, this may lead to under-estimation of the radius of the white dwarf compared to that of its companion. I show that the effect is significant for plausible binary parameters, and that it leads to ~25% reduction in the transit depth in the system KPD 1930+2752. The reduction of eclipse depth is degenerate with the stellar radius ratio, and therefore cannot be used to establish the existence of lensing. A second order effect of the light bending is to steepen the ingress and egress features of the secondary eclipse relative to the primary eclipse, although it will be difficult to see this in practice. I consider also binaries containing neutron stars and black-holes. I conclude that, although relatively large effects are possible in such systems, a combination of rarity, faintness and intrinsic variability make it unlikely that lensing will be detectable in them.

T. R. Marsh

2000-12-18T23:59:59.000Z

28

Disentangling dark sector models using weak lensing statistics  

E-Print Network [OSTI]

We perform multi-plane ray-tracing using the GLAMER gravitational lensing code within high-resolution light-cones extracted from the CoDECS simulations: a suite of cosmological runs featuring a coupling between Dark Energy and Cold Dark Matter. We show that the presence of the coupling is evident not only in the redshift evolution of the normalisation of the convergence power spectrum, but also in differences in non-linear structure formation with respect to {\\Lambda}CDM. Using a tomographic approach under the assumption of a {\\Lambda}CDM cosmology, we demonstrate that weak lensing measurements would result in a {\\sigma}8 value that changes with the source redshift if the true underlying cosmology is a coupled Dark Energy one. This provides a generic null test for these types of models. We also find that different models of coupled Dark Energy can show either an enhanced or a suppressed correlation between convergence maps with differing source redshifts as compared to {\\Lambda}CDM. This would provide a direc...

Giocoli, Carlo; Baldi, Marco; Meneghetti, Massimo; Moscardini, Lauro; Petkova, Margarita; -,; Astronomia, Dipartimento di Fisica e; di Bologna, Alma Mater Studiorum Università; di Bologna, INAF - Osservatorio Astronomico; di Bologna, INFN - Sezione; Université, Aix Marseille; CNRS,; LAM,; France,; Laboratory, Jet Propulsion; Physics, Department of; Ludwig-Maximilians-Universitaet),

2015-01-01T23:59:59.000Z

29

What is Gravitational Lensing? (LBNL Summer Lecture Series)  

ScienceCinema (OSTI)

Summer Lecture Series 2009: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

Leauthaud, Alexie; Nakajima, Reiko [Berkeley Center for Cosmological Physics

2011-04-28T23:59:59.000Z

30

Decaying $?$ cosmologies and statistical properties of gravitational lenses  

E-Print Network [OSTI]

In this paper we investigate the statistical properties of gravitational lenses for models in which a cosmological term decreases with time as $\\Lambda \\propto a^{-m}$, where $a$ is the scale factor and $m$ is a parameter ($0 \\leq m }{\\sim}2$ have high likelihood to reproduce the observed lens statistics in the HST snapshot survey.

L. F. Bloomfield Torres; I. Waga

1995-05-01T23:59:59.000Z

31

Testing gravity with halo density profiles observed through gravitational lensing  

SciTech Connect (OSTI)

We present a new test of the modified gravity endowed with the Vainshtein mechanism with the density profile of a galaxy cluster halo observed through gravitational lensing. A scalar degree of freedom in the galileon modified gravity is screened by the Vainshtein mechanism to recover Newtonian gravity in high-density regions, however it might not be completely hidden on the outer side of a cluster of galaxies. Then the modified gravity might yield an observational signature in a surface mass density of a cluster of galaxies measured through gravitational lensing, since the scalar field could contribute to the lensing potential. We investigate how the transition in the Vainshtein mechanism affects the surface mass density observed through gravitational lensing, assuming that the density profile of a cluster of galaxies follows the original Navarro-Frenk-White (NFW) profile, the generalized NFW profile and the Einasto profile. We compare the theoretical predictions with observational results of the surface mass density reported recently by other researchers. We obtain constraints on the amplitude and the typical scale of the transition in the Vainshtein mechanism in a subclass of the generalized galileon model.

Narikawa, Tatsuya; Yamamoto, Kazuhiro, E-mail: narikawa@theo.phys.sci.hiroshima-u.ac.jp, E-mail: kazuhiro@hiroshima-u.ac.jp [Department of Physical Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan)

2012-05-01T23:59:59.000Z

32

A New Weak Lensing Analysis of MS1224.7+2007  

E-Print Network [OSTI]

Galaxy cluster mass distributions are useful probes of Omega_0 and the nature of the dark matter. Large clusters will distort the observed shapes of background galaxies through gravitational lensing allowing the measurement of the cluster mass distributions. For most cases, the agreement between weak lensing and radial velocity mass measurements of clusters is reasonably good. There is, however, one significant exception, the z=0.32 cluster MS1224.7+2007, which has a lensing mass substantially larger than the virial mass and also a very high mass-to-light ratio. Since this controversial object might be an unusually dark mass a follow-up study is definitely warranted. In this paper we study the mass and light distributions of MS1224+2007 out to a projected radius of 800/h kpc by measuring the gravitationally-induced distortions of background galaxies. We detect a shear signal in the background galaxies in the radial range 27.5 arcsec < r < 275 arcsec at the 5.5 sigma level. The resultant mass map exhibits a peak centered on the dominant cluster galaxy and strong evidence for substructure which is even more strongly seen in the galaxy distribution. Assuming all the detected shear is due to mass at z=0.32 we find cluster mass-to-light ratio of M/L_R = 640 +/- 150. The mass profile is quite flat compared to other clusters, disagreeing with a pseudo-singular isothermal sphere at the 95% confidence level. Our mass and M/L estimates are consistent with the previous weak lensing result. The discrepancy between the lensing and virial mass remains although it might be partially explained by subclustering and infall perpendicular to the line-of-site. This cluster remains a candidate dark object deficient in baryons and as such severely tests cosmological models.

Philippe Fischer

1999-01-29T23:59:59.000Z

33

Gravitational Lensing by Self-Dual Black Holes in Loop Quantum Gravity  

E-Print Network [OSTI]

We study gravitational lensing by a recently proposed black hole solution in Loop Quantum Gravity. We highlight the fact that the quantum gravity corrections to the Schwarzschild metric in this model evade the `mass suppression' effects (that the usual quantum gravity corrections are susceptible to) by virtue of one of the parameters in the model being dimensionless, which is unlike any other quantum gravity motivated parameter. Gravitational lensing in the strong and weak deflection regimes is studied and a sample consistency relation is presented which could serve as a test of this model. We discuss that though the consistency relation for this model is qualitatively similar to what would have been in Brans-Dicke, in general it can be a good discriminator between many alternative theories. Although the observational prospects do not seem to be very optimistic even for a galactic supermassive black hole case, time delay between relativistic images for billion solar mass black holes in other galaxies might be...

Sahu, Satyabrata; Narasimha, D

2015-01-01T23:59:59.000Z

34

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

35

A Comparison of Cosmological Models Using Strong Gravitational Lensing Galaxies  

E-Print Network [OSTI]

Strongly gravitationally lensed quasar-galaxy systems allow us to compare competing cosmologies as long as one can be reasonably sure of the mass distribution within the intervening lens. In this paper, we assemble a catalog of 69 such systems, and carry out a one-on-one comparison between the standard model, LCDM, and the R_h=ct Universe. We find that both models account for the lens observations quite well, though the precision of these measurements does not appear to be good enough to favor one model over the other. Part of the reason is the so-called bulge-halo conspiracy that, on average, results in a baryonic velocity dispersion within a fraction of the optical effective radius virtually identical to that expected for the whole luminous-dark matter distribution. Given the limitations of doing precision cosmological testing using the current sample, we also carry out Monte Carlo simulations based on the current lens measurements to estimate how large the source catalog would have to be in order to rule out either model at a ~99.7% confidence level. We find that if the real cosmology is LCDM, a sample of ~200 strong gravitational lenses would be sufficient to rule out R_h=ct at this level of accuracy, while ~300 strong gravitational lenses would be required to rule out LCDM if the real Universe were instead R_h=ct. The difference in required sample size reflects the greater number of free parameters available to fit the data with LCDM. We point out that, should the R_h=ct Universe eventually emerge as the correct cosmology, its lack of any free parameters for this kind of work will provide a remarkably powerful probe of the mass structure in lensing galaxies, and a means of better understanding the origin of the bulge-halo conspiracy.

Fulvio Melia; Jun-Jie Wei; Xue-Feng Wu

2014-10-03T23:59:59.000Z

36

Broad Iron Emission from Gravitationally Lensed Quasars Observed by Chandra  

E-Print Network [OSTI]

Recent work has demonstrated the potential of gravitationally lensed quasars to extend measurements of black hole spin out to high-redshift with the current generation of X-ray observatories. Here we present an analysis of a large sample of 27 lensed quasars in the redshift range 1.0permit the detection of iron emission from the inner accretion disk in individual cases in our sample, we find significant structure in the stacked residuals. In addition to the narrow core, seen almost ubiquitously in local AGN, we find evidence for an additional underlying broad component from the inner accretion disk, with a clear red wing to the emission profile. Based on simulations, we find the detection of this broader component to be significant at greater than the 3-sigma level. This implies that iron emission...

Walton, D J; Miller, J M; Reis, R C; Stern, D; Harrison, F A

2015-01-01T23:59:59.000Z

37

Constraints on warm dark matter from weak lensing in anomalous quadruple lenses  

E-Print Network [OSTI]

We investigate the weak lensing effect by line-of-sight structures with a surface mass density of solar mass/arcsec^2 in QSO-galaxy quadruple lens systems. Using high-resolution N-body simulations in warm dark matter (WDM) models and observed four quadruple lenses that show anomalies in the flux ratios, we obtain constraints on the mass of thermal WDM, m_WDM>= 1.3keV(95%CL), which is consistent with those from Lyman-$\\alpha$ forests and the number counts of high-redshift galaxies at z>4. Our results show that WDM with a free-streaming comoving wavenumber k_{fs} <= 27 h/Mpc is disfavored as the major component of cosmological density at redshifts 0.5 <~ z <~ 4.

Kaiki Taro Inoue; Ryuichi Takahashi; Tomo Takahashi; Tomoaki Ishiyama

2014-09-04T23:59:59.000Z

38

Gravitational lens equation for embedded lenses; magnification and ellipticity  

SciTech Connect (OSTI)

We give the lens equation for light deflections caused by point mass condensations in an otherwise spatially homogeneous and flat universe. We assume the signal from a distant source is deflected by a single condensation before it reaches the observer. We call this deflector an embedded lens because the deflecting mass is part of the mean density. The embedded lens equation differs from the conventional lens equation because the deflector mass is not simply an addition to the cosmic mean. We prescribe an iteration scheme to solve this new lens equation and use it to compare our results with standard linear lensing theory. We also compute analytic expressions for the lowest order corrections to image amplifications and distortions caused by incorporating the lensing mass into the mean. We use these results to estimate the effect of embedding on strong lensing magnifications and ellipticities and find only small effects, <1%, contrary to what we have found for time delays and for weak lensing, {approx}5%.

Chen, B. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks, Norman, Oklahoma 73019 (United States); Mathematics Department, University of Oklahoma, 601 Elm Avenue, Norman, Oklahoma 73019 (United States); Kantowski, R.; Dai, X. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks, Norman, Oklahoma 73019 (United States)

2011-10-15T23:59:59.000Z

39

Three Gravitational Lenses for the Price of One: Enhanced Strong Lensing Through Galaxy Clustering  

SciTech Connect (OSTI)

We report the serendipitous discovery of two strong gravitational lens candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, each less than 40'' from the previously known gravitational lens system CLASS B1608+656. The redshifts of both lens galaxies have been measured with Keck and Gemini: one is a member of a small galaxy group at z {approx} 0.63, which also includes the lensing galaxy in the B1608+656 system, and the second is a member of a foreground group at z {approx} 0.43. By measuring the effective radii and surface brightnesses of the two lens galaxies, we infer their velocity dispersions based on the passively evolving Fundamental Plane (FP) relation. Elliptical isothermal lens mass models are able to explain their image configurations within the lens hypothesis, with a velocity dispersion compatible with that estimated from the FP for a reasonable source-redshift range. Based on the large number of massive early-type galaxies in the field and the number-density of faint blue galaxies, the presence of two additional lens systems around CLASS B1608+656 is not unlikely in hindsight. Gravitational lens galaxies are predominantly early-type galaxies, which are clustered, and the lensed quasar host galaxies are also clustered. Therefore, obtaining deep high-resolution images of the fields around known strong lens systems is an excellent method of enhancing the probability of finding additional strong gravitational lens systems.

Fassnacht, Chris D.; McKean, J.P.; Koopmans, L.V.E.; Treu, T.; Blandford, R.D.; Auger, M.W.; Jeltema, T.E.; Lubin, L.M.; Margoniner, V.E.; Wittman, D.; /UC, Davis

2006-04-03T23:59:59.000Z

40

Gravitational lensing and the angular-diameter distance relation  

E-Print Network [OSTI]

We show that the usual relation between redshift and angular-diameter distance can be obtained by considering light from a source to be gravitationally lensed by material that lies in the telescope beam as it passes from source to observer through an otherwise empty universe. This derivation yields an equation for the dependence of angular diameter on redshift in an inhomogeneous universe. We use this equation to model the distribution of angular-diameter distance for redshift z=3 in a realistically clustered cosmology. The distribution is such that attempts to determine q_0 from angular-diameter distances will systematically underestimate q_0 by ~0.15, and large samples would be required to beat down the intrinsic dispersion in measured values of q_0.

Fedja Hadrovic; James Binney

1997-08-13T23:59:59.000Z

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.


41

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; Muñoz, 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; Harpsøe, K; Hinse, T C; Hundertmark, M; Jørgensen, 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

42

Numerical wave optics and the lensing of gravitational waves by globular clusters  

E-Print Network [OSTI]

We consider the possible effects of gravitational lensing by globular clusters on gravitational waves from asymmetric neutron stars in our galaxy. In the lensing of gravitational waves, the long wavelength, compared with the usual case of optical lensing, can lead to the geometrical optics approximation being invalid, in which case a wave optical solution is necessary. In general, wave optical solutions can only be obtained numerically. We describe a computational method that is particularly well suited to numerical wave optics. This method enables us to compare the properties of several lens models for globular clusters without ever calling upon the geometrical optics approximation, though that approximation would sometimes have been valid. Finally, we estimate the probability that lensing by a globular cluster will significantly affect the detection, by ground-based laser interferometer detectors such as LIGO, of gravitational waves from an asymmetric neutron star in our galaxy, finding that the probability is insignificantly small.

Andrew J. Moylan; David E. McClelland; Susan M. Scott; Antony C. Searle; G. V. Bicknell

2007-10-16T23:59:59.000Z

43

Constraints on early-type galaxy structure from spectroscopically selected gravitational lenses  

E-Print Network [OSTI]

This thesis describes all aspects of a unique spectroscopic survey for strong galaxy-galaxy gravitational lenses: motivation, candidate selection, ground-based spectroscopic follow-up, Hubble Space Telescope imaging, data ...

Bolton, Adam Stallard

2005-01-01T23:59:59.000Z

44

ON THE ACCURACY OF WEAK-LENSING CLUSTER MASS RECONSTRUCTIONS  

SciTech Connect (OSTI)

We study the bias and scatter in mass measurements of galaxy clusters resulting from fitting a spherically symmetric Navarro, Frenk, and White model to the reduced tangential shear profile measured in weak-lensing (WL) observations. The reduced shear profiles are generated for {approx}10{sup 4} cluster-sized halos formed in a {Lambda}CDM cosmological N-body simulation of a 1 h{sup -1} Gpc box. In agreement with previous studies, we find that the scatter in the WL masses derived using this fitting method has irreducible contributions from the triaxial shapes of cluster-sized halos and uncorrelated large-scale matter projections along the line of sight. Additionally, we find that correlated large-scale structure within several virial radii of clusters contributes a smaller, but nevertheless significant, amount to the scatter. The intrinsic scatter due to these physical sources is {approx}20% for massive clusters and can be as high as {approx}30% for group-sized systems. For current, ground-based observations, however, the total scatter should be dominated by shape noise from the background galaxies used to measure the shear. Importantly, we find that WL mass measurements can have a small, {approx}5%-10%, but non-negligible amount of bias. Given that WL measurements of cluster masses are a powerful way to calibrate cluster mass-observable relations for precision cosmological constraints, we strongly emphasize that a robust calibration of the bias requires detailed simulations that include more observational effects than we consider here. Such a calibration exercise needs to be carried out for each specific WL mass estimation method, as the details of the method determine in part the expected scatter and bias. We present an iterative method for estimating mass M{sub 500c} that can eliminate the bias for analyses of ground-based data.

Becker, Matthew R. [Department of Physics, 5720 S. Ellis Avenue, University of Chicago, Chicago, IL 60637 (United States); Kravtsov, Andrey V. [Kavli Institute for Cosmological Physics, 5640 South Ellis Avenue, University of Chicago, Chicago, IL 60637 (United States)

2011-10-10T23:59:59.000Z

45

A Comparison of Cosmological Models Using Strong Gravitational Lensing Galaxies  

E-Print Network [OSTI]

Strongly gravitationally lensed quasar-galaxy systems allow us to compare competing cosmologies as long as one can be reasonably sure of the mass distribution within the intervening lens. In this paper, we assemble a catalog of 69 such systems, and carry out a one-on-one comparison between the standard model, LCDM, and the R_h=ct Universe. We find that both models account for the lens observations quite well, though the precision of these measurements does not appear to be good enough to favor one model over the other. Part of the reason is the so-called bulge-halo conspiracy that, on average, results in a baryonic velocity dispersion within a fraction of the optical effective radius virtually identical to that expected for the whole luminous-dark matter distribution. Given the limitations of doing precision cosmological testing using the current sample, we also carry out Monte Carlo simulations based on the current lens measurements to estimate how large the source catalog would have to be in order to rule o...

Melia, Fulvio; Wu, Xue-Feng

2014-01-01T23:59:59.000Z

46

Gravitational lensing of quasars by edge-on spiral galaxies  

E-Print Network [OSTI]

In this thesis, I studied the lensed quasar CX2201-3201, which is lensed by an edge-on spiral galaxy. The unusually high tilt of the spiral galaxy provides us with a rare opportunity for mass modeling. In addition, the ...

Wang, Emily P

2007-01-01T23:59:59.000Z

47

The Effect of the Cosmic Web on Cluster Weak Lensing Mass Estimates  

E-Print Network [OSTI]

In modern hierarchical theories of structure formation, rich clusters of galaxies form at the vertices of a weblike distribution of matter, with filaments emanating from them to large distances and with smaller objects forming and draining in along these filaments. The amount of mass contained in structure near the cluster can be comparable to the collapsed mass of the cluster itself. As the lensing kernel is quite broad along the line of sight around cluster lenses with typical redshifts near z=0.5, structures many Mpc away from the cluster are essentially at the same location as the cluster itself, when considering their effect on the cluster's weak lensing signal. We use large-scale numerical simulations of structure formation in a Lambda-dominated cold dark matter model to quantify the effect that large-scale structure near clusters has upon the cluster masses deduced from weak lensing analysis. A correction for the scatter in possible observed lensing masses should be included when interpreting mass functions from weak lensing surveys.

Christopher A. Metzler; Martin White; Chris Loken

2001-03-08T23:59:59.000Z

48

Distortion of the luminosity function of high-redshift galaxies by gravitational lensing  

E-Print Network [OSTI]

The observed properties of high redshift galaxies depend on the underlying foreground distribution of large scale structure, which distorts their intrinsic properties via gravitational lensing. We focus on the regime where the dominant contribution originates from a single lens and examine the statistics of gravitational lensing by a population of virialized and non-virialized structures using sub-mm galaxies at z ~ 2.6 and Lyman-break galaxies at redshifts z ~ 6-15 as the background sources. We quantify the effect of lensing on the luminosity function of the high redshift sources, focusing on the intermediate and small magnifications (mu < 3) which affect the majority of the background galaxies. We show that depending on the intrinsic properties of the background galaxies, gravitational lensing can significantly affect the observed luminosity function even when no obvious strong lenses are present. Finally, we find that in the case of the Lyman-break galaxies it is important to account for the surface bri...

Fialkov, Anastasia

2015-01-01T23:59:59.000Z

49

Gravitational Lensing Limits on Cold Dark Matter and Its Variants  

E-Print Network [OSTI]

Standard $\\Omega_0=1$ cold dark matter (CDM) needs $0.27 < \\sigma_8 < 0.63$ ($2\\sigma$) to fit the observed number of large separation lenses, and the constraint is nearly independent of $H_0=100h^{-1}\\kms$ Mpc$^{-1}$. This range is strongly inconsistent with the COBE estimate of $\\sigma_8=(2.8\\pm0.2)h$. Tilting the primordial spectrum $\\propto k^n$ from $n=1$ to $0.3 \\ltorder n \\ltorder 0.7$, using an effective Hubble constant of $0.15 \\ltorder \\Gamma=h \\ltorder 0.30$, or reducing the matter density to $0.15 \\ltorder \\Omega_0 h \\ltorder 0.3$ either with no cosmological constant ($\\lambda_0=0$) or in a flat universe with a cosmological constant ($\\Omega_0+\\lambda_0=1$) can bring the lensing estimate of $\\sigma_8$ into agreement with the COBE estimates. The models and values for $\\sigma_8$ consistent with both lensing and COBE match the estimates from the local number density of clusters and correlation functions. The conclusions are insensitive to systematic errors except for the assumption that cluster core radii are singular. If clusters with $\\rho\\propto(r^2+s^2)^{-1}$ have core radii exceeding $s = 15h^{-1}\\sigma_3^2$ kpc for a cluster with velocity dispersion $\\sigma=10^3\\sigma_3 \\kms$ then the estimates are invalid. There is, however, a fine tuning problem in making the cluster core radii large enough to invalidate the estimates of $\\sigma_8$ while producing several lenses that do not have central or ``odd images.'' The estimated completeness of the current samples of lenses larger than $5\\parcs0$ is 20\\%, because neither quasar surveys nor lens surveys are optimized to this class of lenses.

Christopher S. Kochanek

1994-11-19T23:59:59.000Z

50

Strong and Weak Lensing United III: Measuring the Mass Distribution of the Merging Galaxy Cluster 1E0657-56  

SciTech Connect (OSTI)

The galaxy cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subcluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of ''weakly'' lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the underlying cluster potential. This map provides the best available quantification of the total mass of the central part of the cluster. We also confirm the result from Clowe et al. (2004, 2006a) that the total mass does not trace the baryonic mass.

Bradac, Marusa; Clowe, Douglas; Gonzalez, Anthony H.; Marshall, Phil; Forman, William; Jones, Christine; Markevitch, Maxim; Randall, Scott; Schrabback, Tim; Zaritsky,; /KIPAC, Menlo Park /Bonn, Inst. Astrophys. /Arizona U., Astron. Dept. - Steward Observ. /Florida U. /Harvard-Smithsonian Ctr. Astrophys.

2006-09-27T23:59:59.000Z

51

SCALING RELATIONS AND OVERABUNDANCE OF MASSIVE CLUSTERS AT z {approx}> 1 FROM WEAK-LENSING STUDIES WITH THE HUBBLE SPACE TELESCOPE  

SciTech Connect (OSTI)

We present weak gravitational lensing analysis of 22 high-redshift (z {approx}> 1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other high-z clusters, we compare gravitational lensing masses of these clusters with other observables. We revisit the question whether the presence of the most massive clusters in our sample is in tension with the current {Lambda}CDM structure formation paradigm. We find that the lensing masses are tightly correlated with the gas temperatures and establish, for the first time, the lensing mass-temperature relation at z {approx}> 1. For the power-law slope of the M-T{sub X} relation (M{proportional_to}T{sup {alpha}}), we obtain {alpha} = 1.54 {+-} 0.23. This is consistent with the theoretical self-similar prediction {alpha} = 3/2 and with the results previously reported in the literature for much lower redshift samples. However, our normalization is lower than the previous results by 20%-30%, indicating that the normalization in the M-T{sub X} relation might evolve. After correcting for Eddington bias and updating the discovery area with a more conservative choice, we find that the existence of the most massive clusters in our sample still provides a tension with the current {Lambda}CDM model. The combined probability of finding the four most massive clusters in this sample after the marginalization over cosmological parameters is less than 1%.

Jee, M. J.; Lubin, L.; Stanford, S. A. [Department of Physics, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Dawson, K. S.; Harris, D. W. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Hoekstra, H. [Leiden Observatory, Leiden University, Leiden (Netherlands); Perlmutter, S.; Suzuki, N.; Meyers, J.; Barbary, K. [E.O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720 (United States); Rosati, P. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching (Germany); Brodwin, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Koester, B.; Gladders, M. D. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Postman, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Barrientos, F. [Department of Astronomy and Astrophysics, Universidad Catolica de Chile, Santiago (Chile); Eisenhardt, P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Ford, H. C. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Gilbank, D. G. [Department of Physics and Astronomy, University Of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Gonzalez, A. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States)

2011-08-20T23:59:59.000Z

52

Resolving the High Energy Universe with Strong Gravitational Lensing: The Case of PKS 1830-211  

E-Print Network [OSTI]

Gravitational lensing is a potentially powerful tool for elucidating the origin of gamma-ray emission from distant sources. Cosmic lenses magnify the emission from distance sources and produce time delays between mirage images. Gravitationally-induced time delays depend on the position of the emitting regions in the source plane. The Fermi/LAT satellite continuously monitors the entire sky and detects gamma-ray flares, including those from gravitationally-lensed blazars. Therefore, temporal resolution at gamma-ray energies can be used to measure these time delays, which, in turn, can be used to resolve the origin of the gamma-ray flares spatially. We provide a guide to the application and Monte Carlo simulation of three techniques for analyzing these unresolved light curves: the Autocorrelation Function, the Double Power Spectrum, and the Maximum Peak Method. We apply these methods to derive time delays from the gamma-ray light curve of the gravitationally-lensed blazar PKS 1830-211. The result of temporal an...

Barnacka, Anna; Dell'Antonio, Ian P; Benbow, Wystan

2015-01-01T23:59:59.000Z

53

Gravitational Lensing by Power-Law Mass Distributions: A Fast and Exact Series Approach  

E-Print Network [OSTI]

We present an analytical formulation of gravitational lensing using familiar triaxial power-law mass distributions, where the 3-dimensional mass density is given by $\\rho(X,Y,Z) = \\rho_0 [1 + (\\frac{X}{a})^2 + (\\frac{Y}{b})^2 + (\\frac{Z}{c})^2]^{-\

Kyu-Hyun Chae; Valery K. Khersonsky; David A. Turnshek

1998-08-31T23:59:59.000Z

54

High-Resolution Radio Imaging of Gravitational Lensing Candidates in the 1 Jansky BL Lac Sample  

E-Print Network [OSTI]

While BL Lacertae objects are widely believed to be highly beamed, low-luminosity radio galaxies, many radio-selected BL Lacs have extended radio power levels and optical emission lines that are too luminous to be low-luminosity radio galaxies. Also, Stocke & Rector discovered an excess of MgII absorption systems along BL Lac sightlines compared to quasars, suggesting that gravitational lensing may be another means of creating the BL Lac phenomenon in some cases. We present a search for gravitationally-lensed BL Lacs with deep, high-resolution, two-frequency VLA radio maps of seven lensing candidates from the 1 Jansky BL Lac sample. We find that none of these objects are resolved into an Einstein ring like B 0218+357, nor do any show multiple images of the core. All of the lensing candidates that were resolved show a flat-spectrum core and very unusual, steep-spectrum extended morphology that is incompatible with a multiply lensed system. Thus, while these observations do not rule out microlensing, no macrolensing is observed.

T. A. Rector; J. T. Stocke

2003-02-19T23:59:59.000Z

55

A Hubble Space Telescope Survey of X-ray Luminous Galaxy Clusters: Gravitationally Lensed Arcs and EROs  

E-Print Network [OSTI]

We are conducting a systematic lensing survey of X-ray luminous galaxy clusters at z~0.2 using the Hubble Space Telescope and large ground-based telescopes. We summarize initial results from our survey, including a measurement of the inner slope of the mass profile of A383, and a search for gravitationally lensed Extremely Red Objects.

Graham P. Smith

2002-01-15T23:59:59.000Z

56

Impact of Baryonic Processes on Weak Lensing Cosmology: Higher-Order Statistics and Parameter Bias  

E-Print Network [OSTI]

We study the impact of baryonic physics on cosmological parameter estimation with weak lensing surveys. We run a set of cosmological hydrodynamics simulations with different galaxy formation models. We then perform ray-tracing simulations through the total matter density field to generate 100 independent convergence maps of 25 deg$^2$ field-of-view, and use them to examine the ability of the following three lensing statistics as cosmological probes; power spectrum, peak counts, and Minkowski Functionals. For the upcoming wide-field observations such as Subaru Hyper Suprime-Cam (HSC) survey with a sky coverage of 1400 deg$^2$, the higher-order statistics provide tight constraints on the matter density, density fluctuation amplitude, and dark energy equation of state, but appreciable parameter bias is induced by the baryonic processes such as gas cooling and stellar feedback. When we use power spectrum, peak counts, and Minkowski Functionals, the relative bias in the dark energy equation of state parameter $w$ ...

Osato, Ken; Yoshida, Naoki

2015-01-01T23:59:59.000Z

57

The impact of spurious shear on cosmological parameter estimates from weak lensing observables  

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

Residual errors in shear measurements, after corrections for instrument systematics and atmospheric effects, can impact cosmological parameters derived from weak lensing observations. Here we combine convergence maps from our suite of ray-tracing simulations with random realizations of spurious shear. This allows us to quantify the errors and biases of the triplet (?m,w,?8) derived from the power spectrum (PS), as well as from three different sets of non-Gaussian statistics of the lensing convergence field: Minkowski functionals (MFs), low-order moments (LMs), and peak counts (PKs). Our main results are as follows: (i) We find an order of magnitude smaller biases from the PS than in previous work. (ii) The PS and LM yield biases much smaller than the morphological statistics (MF, PK). (iii) For strictly Gaussian spurious shear with integrated amplitude as low as its current estimate of ?sys2?10-7, biases from the PS and LM would be unimportant even for a survey with the statistical power of Large Synoptic Survey Telescope. However, we find that for surveys larger than ?100 deg2, non-Gaussianity in the noise (not included in our analysis) will likely be important and must be quantified to assess the biases. (iv) The morphological statistics (MF, PK) introduce important biases even for Gaussian noise, which must be corrected in large surveys. The biases are in different directions in (?m,w,?8) parameter space, allowing self-calibration by combining multiple statistics. Our results warrant follow-up studies with more extensive lensing simulations and more accurate spurious shear estimates.

Petri, Andrea [Brookhaven National Laboratory (BNL), Upton, NY (United States); Columbia Univ., New York, NY (United States); May, Morgan [Brookhaven National Laboratory (BNL), Upton, NY (United States); Haiman, Zoltan [Columbia Univ., New York, NY (United States); Kratochvil, Jan M. [Univ. of KwaZulu-Natal, Durban (South Africa)

2014-12-01T23:59:59.000Z

58

Cosmology Constraints from the Weak Lensing Peak Counts and the Power Spectrum in CFHTLenS  

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

?Lensing peaks have been proposed as a useful statistic, containing cosmological information from non-Gaussianities that is inaccessible from traditional two-point statistics such as the power spectrum or two-point correlation functions. Here we examine constraints on cosmological parameters from weak lensing peak counts, using the publicly available data from the 154 deg2 CFHTLenS survey. We utilize a new suite of ray-tracing N-body simulations on a grid of 91 cosmological models, covering broad ranges of the three parameters ?m, ?8, and w, and replicating the galaxy sky positions, redshifts, and shape noise in the CFHTLenS observations. We then build an emulator that interpolates the power spectrum and the peak counts to an accuracy of ? 5%, and compute the likelihood in the three-dimensional parameter space (?m, ?8, w) from both observables. We find that constraints from peak counts are comparable to those from the power spectrum, and somewhat tighter when different smoothing scales are combined. Neither observable can constrain w without external data. When the power spectrum and peak counts are combined, the area of the error “banana” in the (?m, ?8) plane reduces by a factor of ? two, compared to using the power spectrum alone. For a flat ? cold dark matter model, combining both statistics, we obtain the constraint ?8(?m/0.27)0.63 = 0.85+0.03-0.03.

Liu, Jia [Department of Astronomy and Astrophysics, Columbia University, New York, NY, (United States); May, Morgan [Physics Department, Brookhaven National Laboratory, Upton, NY, (United States); Petri, Andrea [Department of Physics, Columbia University, New York, NY, (United States); Haiman, Zoltan [Department of Astronomy and Astrophysics, Columbia University, New York, NY, (United States); Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Columbia University, New York, (United States); Hui, Lam [Department of Physics, Columbia University, New York, NY, (United States); Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Columbia University, New York, (United States); Kratochvil, Jan M. [Astrophysics and Cosmology Research Unit, University of KwaZulu-Natal, Westville, Durban, (South Africa)

2015-03-01T23:59:59.000Z

59

A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: The Redshift Catalog  

E-Print Network [OSTI]

We present the spectroscopic redshift catalog from a wide-field survey of the fields of 28 galaxy-mass strong gravitational lenses. We discuss the acquisition and reduction of the survey data, collected over 40 nights of 6.5m MMT and Magellan time, employing four different multi-object spectrographs. We determine that no biases are introduced by combining datasets obtained with different instrument/spectrograph combinations. Special care is taken to determine redshift uncertainties using repeat observations. The redshift catalog consists of 9768 new and unique galaxy redshifts. 82.4% of the catalog redshifts are between z=0.1 and z=0.7, and the catalog median redshift is z=0.36. The data from this survey will be used to study the lens environments and line-of-sight structures to gain a better understanding of the effects of large scale structure on lens statistics and lens-derived parameters.

Momcheva, Ivelina; Cool, Richard J; Keeton, Charles R; Zabludoff, Ann I

2015-01-01T23:59:59.000Z

60

A robust and efficient method for calculating the magnification of extended sources caused by gravitational lenses  

E-Print Network [OSTI]

To determine the magnification of an extended source caused by gravitational lensing one has to perform a two-dimensional integral over point-source magnifications in general. Since the point-source magnification jumps to an infinite value on caustics, special care is required. For a uniformly bright source, it has been shown earlier that the calculation simplifies if one determines the magnification from the area of the images of the extended source by applying Green's theorem so that one ends up with a one-dimensional integration over the image boundaries. This approach is discussed here in detail, and it is shown that it can be used to yield a robust and efficient method also for limb-darkened sources. It is also shown that the centroid shift can be calculated in a similar way.

M. Dominik

1998-04-06T23:59:59.000Z

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

Degeneracies and scaling relations in general power-law models for gravitational lenses  

E-Print Network [OSTI]

The time delay in gravitational lenses can be used to derive the Hubble constant in a relatively simple way. The results of this method are less dependent on astrophysical assumptions than in many other methods. The most important uncertainty is related to the mass model used. We discuss a family of models with a separable radial power-law and an arbitrary angular dependence for the potential psi = r^beta * F(theta). Isothermal potentials are a special case of these models with beta=1. An additional external shear is used to take into account perturbations from other galaxies. Using a simple linear formalism for quadruple lenses, we can derive H0 as a function of the observables and the shear. If the latter is fixed, the result depends on the assumed power-law exponent according to H0 proportional to (2-beta)/beta. The effect of external shear is quantified by introducing a `critical shear' gamma_c as a measure for the amount of shear that changes the result significantly. The analysis shows, that in the general case H0 and gamma_c do not depend on the position of the lens galaxy. We discuss these results and compare with numerical models for a number of real lens systems.

Olaf Wucknitz

2002-02-20T23:59:59.000Z

62

Gravitational Lensing by Spinning Black Holes in Astrophysics, and in the Movie Interstellar  

E-Print Network [OSTI]

Interstellar is the first Hollywood movie to attempt depicting a black hole as it would actually be seen by somebody nearby. For this we developed a code called DNGR (Double Negative Gravitational Renderer) to solve the equations for ray-bundle (light-beam) propagation through the curved spacetime of a spinning (Kerr) black hole, and to render IMAX-quality, rapidly changing images. Our ray-bundle techniques were crucial for achieving IMAX-quality smoothness without flickering. This paper has four purposes: (i) To describe DNGR for physicists and CGI practitioners . (ii) To present the equations we use, when the camera is in arbitrary motion at an arbitrary location near a Kerr black hole, for mapping light sources to camera images via elliptical ray bundles. (iii) To describe new insights, from DNGR, into gravitational lensing when the camera is near the spinning black hole, rather than far away as in almost all prior studies. (iv) To describe how the images of the black hole Gargantua and its accretion disk, in the movie \\emph{Interstellar}, were generated with DNGR. There are no new astrophysical insights in this accretion-disk section of the paper, but disk novices may find it pedagogically interesting, and movie buffs may find its discussions of Interstellar interesting.

Oliver James; Eugenie von Tunzelmann; Paul Franklin; Kip S. Thorne

2015-02-16T23:59:59.000Z

63

Systematic Errors in Future Weak Lensing Surveys: Requirements and Prospects for Self-Calibration  

E-Print Network [OSTI]

We study the impact of systematic errors on planned weak lensing surveys and compute the requirements on their contributions so that they are not a dominant source of the cosmological parameter error budget. The generic types of error we consider are multiplicative and additive errors in measurements of shear, as well as photometric redshift errors. In general, more powerful surveys have stronger systematic requirements. For example, for a SNAP-type survey the multiplicative error in shear needs to be smaller than 1%(fsky/0.025)^{-1/2} of the mean shear in any given redshift bin, while the centroids of photometric redshift bins need to be known to better than 0.003(fsky/0.025)^{-1/2}. With about a factor of two degradation in cosmological parameter errors, future surveys can enter a self-calibration regime, where the mean systematic biases are self-consistently determined from the survey and only higher-order moments of the systematics contribute. Interestingly, once the power spectrum measurements are combined with the bispectrum, the self-calibration regime in the variation of the equation of state of dark energy w_a is attained with only a 20-30% error degradation.

Dragan Huterer; Masahiro Takada; Gary Bernstein; Bhuvnesh Jain

2005-06-02T23:59:59.000Z

64

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

SciTech Connect (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

65

On the Bias of the Distance-Redshift Relation from Gravitational Lensing  

E-Print Network [OSTI]

A long standing question in cosmology is whether gravitational lensing changes the distance-redshift relation $D(z)$ or the mean flux density of sources. Interest in this has been rekindled by recent studies in non-linear relativistic perturbation theory that find biases in both the area of a surface of constant redshift and in the mean distance to this surface, with a fractional bias in both cases on the order of the mean squared convergence $\\langle \\kappa^2 \\rangle$. Any such area bias could alter CMB cosmology, and the corresponding bias in mean flux density could affect supernova cosmology. Here we show that, in an ensemble averaged sense, the perturbation to the area of a surface of constant redshift is in reality much smaller, being on the order of the cumulative bending angle squared, or roughly a part-in-a-million effect. This validates the arguments of Weinberg (1976) that the mean magnification $\\mu$ of sources is unity and of Kibble \\& Lieu (2005) that the mean direction-averaged inverse magni...

Kaiser, Nick

2015-01-01T23:59:59.000Z

66

OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment  

E-Print Network [OSTI]

We present both the technical overview and main science drivers of the fourth phase of the Optical Gravitational Lensing Experiment (hereafter OGLE-IV). OGLE-IV is currently one of the largest sky variability surveys worldwide, targeting the densest stellar regions of the sky. The survey covers over 3000 square degrees in the sky and monitors regularly over a billion sources. The main targets include the inner Galactic Bulge and the Magellanic System. Their photometry spans the range of $12

Udalski, A; Szyma?ski, G

2015-01-01T23:59:59.000Z

67

A Time Delay for the Largest Gravitationally Lensed Quasar: SDSS J1004+4112  

E-Print Network [OSTI]

We present 426 epochs of optical monitoring data spanning 1000 days from December 2003 to June 2006 for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is 38.4+/-2.0 days in the expected sense that B leads A and the overall time ordering is C-B-A-D-E. The measured delay invalidates all published models. The models failed because they neglected the perturbations from cluster member galaxies. Models including the galaxies can fit the data well, but strong conclusions about the cluster mass distribution should await the measurement of the longer, and less substructure sensitive, delays of the C and D images. For these images, a CB delay of 681+/-15 days is plausible but requires confirmation, while CB and AD delays of >560 days and > 800 days are required. We clearly detect microlensing of the A/B images, with the delay-corrected flux ratios changing from B-A=0.44+/-0.01 mag in the first season to 0.29+/-0.01 mag in the second season and 0.32+/-0.01 mag in the third season.

J. Fohlmeister; C. S. Kochanek; E. E. Falco; J. Wambsganss; N. Morgan; C. W. Morgan; E. O. Ofek; D. Maoz; C. R. Keeton; J. C. Barentine; G. Dalton; J. Dembicky; W. Ketzeback; R. McMillan; C. S. Peters

2006-07-21T23:59:59.000Z

68

Testing a phenomenologically extended DGP model with upcoming weak lensing surveys  

SciTech Connect (OSTI)

A phenomenological extension of the well-known brane-world cosmology of Dvali, Gabadadze and Porrati (eDGP) has recently been proposed. In this model, a cosmological-constant-like term is explicitly present as a non-vanishing tension ? on the brane, and an extra parameter ? tunes the cross-over scale r{sub c}, the scale at which higher dimensional gravity effects become non negligible. Since the Hubble parameter in this cosmology reproduces the same ?CDM expansion history, we study how upcoming weak lensing surveys, such as Euclid and DES (Dark Energy Survey), can confirm or rule out this class of models. We perform Monte Carlo Markov Chain simulations to determine the parameters of the model, using Type Ia Supernovæ, H(z) data, Gamma Ray Bursts and Baryon Acoustic Oscillations. We also fit the power spectrum of the temperature anisotropies of the Cosmic Microwave Background to obtain the correct normalisation for the density perturbation power spectrum. Then, we compute the matter and the cosmic shear power spectra, both in the linear and non-linear régimes. The latter is calculated with the two different approaches of Hu and Sawicki (2007) (HS) and Khoury and Wyman (2009) (KW). With the eDGP parameters coming from the Markov Chains, KW reproduces the ?CDM matter power spectrum at both linear and non-linear scales and the ?CDM and eDGP shear signals are degenerate. This result does not hold with the HS prescription. Indeed, Euclid can distinguish the eDGP model from ?CDM because their expected power spectra roughly differ by the 3? uncertainty in the angular scale range 700?

Camera, Stefano; Diaferio, Antonaldo [Dipartimento di Fisica Generale ''A. Avogadro'', Università di Torino, via P. Giuria 1, 10125 Torino (Italy); Cardone, Vincenzo F., E-mail: camera@ph.unito.it, E-mail: diaferio@ph.unito.it, E-mail: winnyenodrac@gmail.com [Dipartimento di Scienze e Tecnologie per l'Ambiente e il Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche (Italy)

2011-01-01T23:59:59.000Z

69

Atmospheric PSF Interpolation for Weak Lensing in Short Exposure Imaging Data  

SciTech Connect (OSTI)

A main science goal for the Large Synoptic Survey Telescope (LSST) is to measure the cosmic shear signal from weak lensing to extreme accuracy. One difficulty, however, is that with the short exposure time ({approx_equal}15 seconds) proposed, the spatial variation of the Point Spread Function (PSF) shapes may be dominated by the atmosphere, in addition to optics errors. While optics errors mainly cause the PSF to vary on angular scales similar or larger than a single CCD sensor, the atmosphere generates stochastic structures on a wide range of angular scales. It thus becomes a challenge to infer the multi-scale, complex atmospheric PSF patterns by interpolating the sparsely sampled stars in the field. In this paper we present a new method, psfent, for interpolating the PSF shape parameters, based on reconstructing underlying shape parameter maps with a multi-scale maximum entropy algorithm. We demonstrate, using images from the LSST Photon Simulator, the performance of our approach relative to a 5th-order polynomial fit (representing the current standard) and a simple boxcar smoothing technique. Quantitatively, psfent predicts more accurate PSF models in all scenarios and the residual PSF errors are spatially less correlated. This improvement in PSF interpolation leads to a factor of 3.5 lower systematic errors in the shear power spectrum on scales smaller than {approx} 13, compared to polynomial fitting. We estimate that with psfent and for stellar densities greater than {approx_equal}1/arcmin{sup 2}, the spurious shear correlation from PSF interpolation, after combining a complete 10-year dataset from LSST, is lower than the corresponding statistical uncertainties on the cosmic shear power spectrum, even under a conservative scenario.

Chang, C.; Marshall, P.J.; Jernigan, J.G.; Peterson, J.R.; Kahn, S.M.; Gull, S.F.; AlSayyad, Y.; Ahmad, Z.; Bankert, J.; Bard, D.; Connolly, A.; Gibson, R.R.; Gilmore, K.; Grace, E.; Hannel, M.; Hodge, M.A.; Jones, L.; Krughoff, S.; Lorenz, S.; Marshall, S.; Meert, A.

2012-09-19T23:59:59.000Z

70

Weak Gravitational Field in Finsler-Randers Space and Raychaudhuri Equation  

E-Print Network [OSTI]

The linearized form of the metric of a Finsler - Randers space is studied in relation to the equations of motion, the deviation of geodesics and the generalized Raychaudhuri equation are given for a weak gravitational field. This equation is also derived in the framework of a tangent bundle. By using Cartan or Berwald-like connections we get some types "gravito - electromagnetic" curvature. In addition we investigate the conditions under which a definite Lagrangian in a Randers space leads to Einstein field equations under the presence of electromagnetic field. Finally, some applications of the weak field in a generalized Finsler spacetime for gravitational waves are given.

P. Stavrinos

2012-09-13T23:59:59.000Z

71

THE SLOAN DIGITAL SKY SURVEY CO-ADD: CROSS-CORRELATION WEAK LENSING AND TOMOGRAPHY OF GALAXY CLUSTERS  

SciTech Connect (OSTI)

The shapes of distant galaxies are sheared by intervening galaxy clusters. We examine this effect in Stripe 82, a 275 deg{sup 2} region observed multiple times in the Sloan Digital Sky Survey (SDSS) and co-added to achieve greater depth. We obtain a mass-richness calibration that is similar to other SDSS analyses, demonstrating that the co-addition process did not adversely affect the lensing signal. We also propose a new parameterization of the effect of tomography on the cluster lensing signal which does not require binning in redshift, and we show that using this parameterization we can detect tomography for stacked clusters at varying redshifts. Finally, due to the sensitivity of the tomographic detection to accurately marginalize over the effect of the cluster mass, we show that tomography at low redshift (where dependence on exact cosmological models is weak) can be used to constrain mass profiles in clusters.

Simet, Melanie; Dodelson, Scott [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Kubo, Jeffrey M.; Annis, James T.; Hao Jiangang; Johnston, David; Lin, Huan; Soares-Santos, Marcelle [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Reis, Ribamar R. R. [Instituto de Fisica, Universidade Federal do Rio de Janeiro (Brazil); Seo, Hee-Jong [Berkeley Center for Cosmological Physics and Berkeley Lab, University of California, Berkeley, CA 94720 (United States)

2012-04-01T23:59:59.000Z

72

Constraining primordial non-Gaussianity with cosmological weak lensing: shear and flexion  

SciTech Connect (OSTI)

We examine the cosmological constraining power of future large-scale weak lensing surveys on the model of the ESA planned mission Euclid, with particular reference to primordial non-Gaussianity. Our analysis considers several different estimators of the projected matter power spectrum, based on both shear and flexion. We review the covariance and Fisher matrix for cosmic shear and evaluate those for cosmic flexion and for the cross-correlation between the two. The bounds provided by cosmic shear alone are looser than previously estimated, mainly due to the reduced sky coverage and background number density of sources for the latest Euclid specifications. New constraints for the local bispectrum shape, marginalized over ?{sub 8}, are at the level of ?f{sub NL} ? 100, with the precise value depending on the exact multipole range that is considered in the analysis. We consider three additional bispectrum shapes, for which the cosmic shear constraints range from ?f{sub NL} ? 340 (equilateral shape) up to ?f{sub NL} ? 500 (orthogonal shape). Also, constraints on the level of non-Gaussianity and on the amplitude of the matter power spectrum ?{sub 8} are almost perfectly anti-correlated, except for the orthogonal bispectrum shape for which they are correlated. The competitiveness of cosmic flexion constraints against cosmic shear ones depends by and large on the galaxy intrinsic flexion noise, that is still virtually unconstrained. Adopting the very high value that has been occasionally used in the literature results in the flexion contribution being basically negligible with respect to the shear one, and for realistic configurations the former does not improve significantly the constraining power of the latter. Since the shear shot noise is white, while the flexion one decreases with decreasing scale, by considering high enough multipoles the two contributions have to become comparable. Extending the analysis up to l{sub max} = 20,000 cosmic flexion, while being still subdominant, improves the shear constraints by ? 10% when added. However on such small scales the highly non-linear clustering of matter, the impact of baryonic physics, and the non-Gaussian part of the covariance matrix make any error estimation uncertain. By considering lower, and possibly more realistic, values of the flexion intrinsic shape noise results in flexion constraining power being a factor of ? 2 better than that of shear, and the bounds on ?{sub 8} and f{sub NL} being improved by a factor of ? 3 upon their combination.

Fedeli, C. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Bartelmann, M. [Zentrum für Astronomie, Universität Heidelberg, Albert-Überle-Straße 2, 69120 Heidelberg (Germany); Moscardini, L., E-mail: cosimo.fedeli@astro.ufl.edu, E-mail: bartelmann@uni-heidelberg.de, E-mail: lauro.moscardini@unibo.it [Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna (Italy)

2012-10-01T23:59:59.000Z

73

VLT/X-SHOOTER NEAR-INFRARED SPECTROSCOPY AND HST IMAGING OF GRAVITATIONALLY LENSED z ? 2 COMPACT QUIESCENT GALAXIES  

SciTech Connect (OSTI)

Quiescent massive galaxies at z ? 2 are thought to be the progenitors of present-day massive ellipticals. Observations revealed them to be extraordinarily compact. Until now, the determination of stellar ages, star formation rates, and dust properties via spectroscopic measurements has been feasible only for the most luminous and massive specimens (?3 × M*). Here we present a spectroscopic study of two near-infrared-selected galaxies that are close to the characteristic stellar mass M* (?0.9 × M* and ?1.3 × M*) and whose observed brightness has been boosted by the gravitational lensing effect. We measure the redshifts of the two galaxies to be z = 1.71 ± 0.02 and z = 2.15 ± 0.01. By fitting stellar population synthesis models to their spectrophotometric spectral energy distributions we determine their ages to be 2.4{sup +0.8}{sub -0.6} Gyr and 1.7 ± 0.3 Gyr, respectively, which implies that the two galaxies have higher mass-to-light ratios than most quiescent z ? 2 galaxies in other studies. We find no direct evidence for active star formation or active galactic nucleus activity in either of the two galaxies, based on the non-detection of emission lines. Based on the derived redshifts and stellar ages we estimate the formation redshifts to be z=4.3{sup +3.4}{sub -1.2} and z=4.3{sup +1.0}{sub -0.6}, respectively. We use the increased spatial resolution due to the gravitational lensing to derive constraints on the morphology. Fitting Sérsic profiles to the de-lensed images of the two galaxies confirms their compactness, with one of them being spheroid-like and the other providing the first confirmation of a passive lenticular galaxy at a spectroscopically derived redshift of z ? 2.

Geier, S.; Man, A. W. S.; Krühler, T.; Toft, S.; Fynbo, J. P. U. [Dark Cosmology Centre, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Richard, J. [Centre de Recherche Astronomique de Lyon, Université Lyon 1, 9 Avenue Charles Andre, F-69230 Saint Genis Laval (France); Marchesini, D., E-mail: sgeier@astro.ku.dk [Department of Physics and Astronomy, Tufts University, Medford, MA 06520 (United States)

2013-11-10T23:59:59.000Z

74

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

SciTech Connect (OSTI)

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

75

A newly discovered DLA and associated Ly-alpha emission in the spectra of the gravitationally lensed quasar UM 673A,B  

E-Print Network [OSTI]

The sightline to the brighter member of the gravitationally lensed quasar pair UM 673A,B intersects a damped Lyman-alpha system (DLA) at z = 1.62650 which, because of its low redshift, has not been recognised before. Our high quality echelle spectra of the pair, obtained with HIRES on the Keck I telescope, show a drop in neutral hydrogen column density N(H I) by a factor of at least 400 between UM 673A and B, indicating that the DLA's extent in this direction is much less than the 2.7 kpc separation between the two sightlines at z = 1.62650. By reassessing this new case together with published data on other QSO pairs, we conclude that the typical size (radius) of DLAs at these redshifts is R ~ (5 +/- 3) kpc, smaller than previously realised. Highly ionized gas associated with the DLA is more extended, as we find only small differences in the C IV absorption profiles between the two sightlines. Coincident with UM 673B, we detect a weak and narrow Ly-alpha emission line which we attribute to star formation acti...

Cooke, Ryan; Steidel, Charles C; King, Lindsay J; Rudie, Gwen C; Rakic, Olivera

2010-01-01T23:59:59.000Z

76

The Red Radio Ring: a gravitationally lensed hyperluminous infrared radio galaxy at z=2.553 discovered through citizen science  

E-Print Network [OSTI]

We report the discovery of a gravitationally lensed hyperluminous infrared galaxy (L_IR~10^13 L_sun) with strong radio emission (L_1.4GHz~10^25 W/Hz) at z=2.553. The source was identified in the citizen science project SpaceWarps through the visual inspection of tens of thousands of iJKs colour composite images of Luminous Red Galaxies (LRGs), groups and clusters of galaxies and quasars. Appearing as a partial Einstein ring (r_e~3") around an LRG at z=0.2, the galaxy is extremely bright in the sub-millimetre for a cosmological source, with the thermal dust emission approaching 1 Jy at peak. The redshift of the lensed galaxy is determined through the detection of the CO(3-2) molecular emission line with the Large Millimetre Telescope's Redshift Search Receiver and through [OIII] and H-alpha line detections in the near-infrared from Subaru/IRCS. We have resolved the radio emission with high resolution (300-400 mas) eMERLIN L-band and JVLA C-band imaging. These observations are used in combination with the near-...

Geach, J E; Verma, A; Marshall, P J; Jackson, N; Belles, P -E; Beswick, R; Baeten, E; Chavez, M; Cornen, C; Cox, B E; Erben, T; Erickson, N J; Garrington, S; Harrison, P A; Harrington, K; Hughes, D H; Ivison, R J; Jordan, C; Lin, Y -T; Leauthaud, A; Lintott, C; Lynn, S; Kapadia, A; Kneib, J -P; Macmillan, C; Makler, M; Miller, G; Montana, A; Mujica, R; Muxlow, T; Narayanan, G; Briain, D O; O'Brien, T; Oguri, M; Paget, E; Parrish, M; Ross, N P; Rozo, E; Rusu, E; Rykoff, E S; Sanchez-Arguelles, D; Simpson, R; Snyder, C; Schloerb, F P; Tecza, M; Van Waerbeke, L; Wilcox, J; Viero, M; Wilson, G W; Yun, M S; Zeballos, M

2015-01-01T23:59:59.000Z

77

Weak equivalence principle for self-gravitating bodies: A sieve for purely metric theories of gravity  

E-Print Network [OSTI]

We propose the almost-geodesic motion of self-gravitating test bodies as a possible selection rule among metric theories of gravity. Starting from a heuristic statement, the "gravitational weak equivalence principle", we build a formal, operative test able to probe the validity of the principle for any metric theory of gravity, in an arbitrary number of spacetime dimensions. We show that, if the theory admits a well-posed variational formulation, this test singles out only the purely metric theories of gravity. This conclusion reproduces known results in the cases of general relativity (also with a cosmological constant term), and scalar-tensor theories, but extends also to debated or unknown scenarios, such as f(R) and Lanczos-Lovelock theories. We thus provide new tools going beyond the standard methods, where the latter turn out to be inconclusive or inapplicable.

Eolo Di Casola; Stefano Liberati; Sebastiano Sonego

2014-04-11T23:59:59.000Z

78

Hard Thermal Loops, Weak Gravitational Fields and The Quark Gluon Energy Momentum Tensor  

E-Print Network [OSTI]

We use an auxiliary field construction to discuss the hard thermal loop effective action associated with massless thermal SU(N) QCD interacting with a weak gravitational field. It is demonstrated that the previous attempt to derive this effective action has only been partially successful and that it is presently only known to first order in the graviton coupling constant. This is still sufficient to enable a calculation of a symmetric traceless quark gluon plasma energy momentum tensor. Finally, we comment on the conserved currents and charges of the derived energy momentum tensor.

E. A. Gaffney

1994-09-13T23:59:59.000Z

79

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

SciTech Connect (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

80

LoCuSS: A COMPARISON OF SUNYAEV-ZEL'DOVICH EFFECT AND GRAVITATIONAL-LENSING MEASUREMENTS OF GALAXY CLUSTERS  

SciTech Connect (OSTI)

We present the first measurement of the relationship between the Sunyaev-Zel'dovich effect (SZE) signal and the mass of galaxy clusters that uses gravitational lensing to measure cluster mass, based on 14 X-ray luminous clusters at z {approx_equal} 0.2 from the Local Cluster Substructure Survey. We measure the integrated Compton y-parameter, Y, and total projected mass of the clusters (M {sub GL}) within a projected clustercentric radius of 350 kpc, corresponding to mean overdensities of 4000-8000 relative to the critical density. We find self-similar scaling between M {sub GL} and Y, with a scatter in mass at fixed Y of 32%. This scatter exceeds that predicted from numerical cluster simulations, however, it is smaller than comparable measurements of the scatter in mass at fixed T{sub X} . We also find no evidence of segregation in Y between disturbed and undisturbed clusters, as had been seen with T{sub X} on the same physical scales. We compare our scaling relation to the Bonamente et al. relation based on mass measurements that assume hydrostatic equilibrium, finding no evidence for a hydrostatic mass bias in cluster cores (M {sub GL} = 0.98 {+-} 0.13 M {sub HSE}), consistent with both predictions from numerical simulations and lensing/X-ray-based measurements of mass-observable scaling relations at larger radii. Overall our results suggest that the SZE may be less sensitive than X-ray observations to the details of cluster physics in cluster cores.

Marrone, Daniel P.; Culverhouse, Thomas; Carlstrom, John E.; Greer, Christopher; Hennessy, Ryan; Leitch, Erik M.; Loh, Michael; Pryke, Clem [Kavli Institute for Cosmological Physics, Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Smith, Graham P.; Hamilton-Morris, Victoria [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Richard, Johan [California Institute of Technology, Mail Code 105-24, Pasadena, CA 91125 (United States); Joy, Marshall [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Bonamente, Massimiliano; Hasler, Nicole [Department of Physics, University of Alabama, Huntsville, AL 35812 (United States); Kneib, Jean-Paul [Laboratoire d'Astrophysique de Marseilles, OAMP, CNRS-Universite Aix-Marseilles, 38 rue Frederic Joliot-Curie, 13388 Marseilles Cedex 13 (France); Hawkins, David; Lamb, James W.; Muchovej, Stephen [Owens Valley Radio Observatory, California Institute of Technology, Big Pine, CA 93513 (United States); Miller, Amber; Mroczkowski, Tony [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)] (and others)

2009-08-20T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


81

Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation  

SciTech Connect (OSTI)

We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. (2007). We present non-parametric inversions of the 2D shear profiles to the mean 3D cluster density and mass profiles in bins of both optical richness and cluster i-band luminosity. Since the mean cluster density profile is proportional to the cluster-mass correlation function, the mean profile is spherically symmetric by the assumptions of large-scale homogeneity and isotropy. We correct the inferred 3D profiles for systematic effects, including non-linear shear and the fact that cluster halos are not all precisely centered on their brightest galaxies. We also model the measured cluster shear profile as a sum of contributions from the brightest central galaxy, the cluster dark matter halo, and neighboring halos. We infer the relations between mean cluster virial mass and optical richness and luminosity over two orders of magnitude in cluster mass; the virial mass at fixed richness or luminosity is determined with a precision of {approx} 13% including both statistical and systematic errors. We also constrain the halo concentration parameter and halo bias as a function of cluster mass; both are in good agreement with predictions from N-body simulations of LCDM models. The methods employed here will be applicable to deeper, wide-area optical surveys that aim to constrain the nature of the dark energy, such as the Dark Energy Survey, the Large Synoptic Survey Telescope and space-based surveys.

Johnston, David E.; Sheldon, Erin S.; Wechsler, Risa H.; Rozo, Eduardo; Koester, Benjamin P.; Frieman, Joshua A.; McKay, Timothy A.; Evrard, August E.; Becker, Matthew; Annis, James

2007-09-28T23:59:59.000Z

82

The serendipitous observation of a gravitationally lensed galaxy at z = 0.9057 from the Blanco Cosmology Survey: The Elliot Arc  

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

We report on the serendipitous discovery in the Blanco Cosmology Survey (BCS) imaging data of a z = 0.9057 galaxy that is being strongly lensed by a massive galaxy cluster at a redshift of z = 0.3838. The lens (BCS J2352-5452) was discovered while examining i- and z-band images being acquired in October 2006 during a BCS observing run. Follow-up spectroscopic observations with the GMOS instrument on the Gemini South 8m telescope confirmed the lensing nature of this system. Using weak plus strong lensing, velocity dispersion, cluster richness N200, and fitting to an NFW cluster mass density profile, we have made three independent estimates of the mass M200 which are all very consistent with each other. The combination of the results from the three methods gives M200 = (5.1 x 1.3) x 1014 circle_dot, which is fully consistent with the individual measurements. The final NFW concentration c200 from the combined fit is c200 = 5.4-1.1+1.4. We have compared our measurements of M200 and c200 with predictions for (a) clusters from ?CDM simulations, (b) lensing selected clusters from simulations, and (c) a real sample of cluster lenses. We find that we are most compatible with the predictions for ?CDM simulations for lensing clusters, and we see no evidence based on this one system for an increased concentration compared to ?CDM. Finally, using the flux measured from the [OII]3727 line we have determined the star formation rate (SFR) of the source galaxy and find it to be rather modest given the assumed lens magnification.

Buckley-Geer, E J; Lin, H; Drabek, E R; Allam, S S; Tucker, D L; Armstrong, R; Barkhouse, W A; Bertin, E; Brodwin, M; Desai, S; Frieman, J A

2011-11-03T23:59:59.000Z

83

The Optical Gravitational Lensing Experiment. Red Clump Stars as a Distance Indicator  

E-Print Network [OSTI]

We present relation of the mean I-band brightness of red clump stars on metallicity. Red clump stars were proposed to be a very attractive standard candle for distance determination. The calibration is based on 284 nearby red giant stars whose high quality spectra allowed to determine accurate individual metal abundances. High quality parallaxes (\\sigma_\\pi / \\pi < 10%) and photometry of these very bright stars come from Hipparcos measurements. Metallicity of the sample covers a large range: -0.6<[Fe/H]<+0.2 dex. We find a weak dependence of the mean I-band brightness on metallicity (about 0.13 mag/dex). What is more important, the range of metallicity of the Hipparcos sample partially overlaps with metallicity of field giants in the LMC, thus making it possible to determine the distance to the LMC by almost direct comparison of brightness of the local Hipparcos red clump giants with that of LMC stars. Photometry of field red clump giants in nine low extinction fields of the LMC halo collected during the OGLE-II microlensing survey compared with the Hipparcos red clump stars data yields the distance modulus to the LMC: (m-M)_LMC=18.24+/-0.08 mag.

A. Udalski

2000-01-14T23:59:59.000Z

84

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 (OSTI)

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

85

Type-Ia Supernova Remnant Shell At $Z=3.5$ Seen In The Three Sightlines Toward The Gravitationally Lensed Qso B1422+231  

E-Print Network [OSTI]

Using the Subaru 8.2m Telescope with an IRCS Echelle spectrograph, we obtained high-resolution (R=10,000) near-infrared (1.01-1.38 \\mu m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z=3.628) consisting of four known lensed images. We detected MgII absorption lines at z=3.54, which show a large variance of column densities (~ 0.3 dex) and velocities (~ 10 km/s) between the sightlines A and B with a projected separation of only 8.4h_{70}^{-1} pc at the redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20-pc scale structure for the same z=3.54 absorption system using optical spectra of images A and C. The observed systematic variances imply that the system is an expanding shell as originally suggested by Rauch et al. By combining the data for three sightlines, we managed to constrain the radius and expansion velocity of the shell (~ 50-100 pc, 130 km/s), concluding that the shell is truly a supernova remnant (SNR) rather ...

Hamano, Satoshi; Kondo, Sohei; Tsujimoto, Takuji; Okoshi, Katsuya; Shigeyama, Toshikazu

2012-01-01T23:59:59.000Z

86

Fast and Accurate Fourier Series Solutions to Gravitational Lensing by A General Family of Two Power-Law Mass Distributions  

E-Print Network [OSTI]

Fourier series solutions to the deflection and magnification by a family of three-dimensional cusped two power-law ellipsoidal mass distributions are presented. The cusped two power-law ellipsoidal mass distributions are characterized by inner and outer power-law radial indices and a break (or, transition) radius. The model family includes mass models mimicking Jaffe, Hernquist, and $\\eta$ models and dark matter halo profiles from numerical simulations. The Fourier series solutions for the cusped two power-law mass distributions are relatively simple, and allow a very fast calculation even for a chosen small fractional calculational error (e.g. $10^{-5}$). These results will be particularly useful for studying lensed systems which provide a number of accurate lensing constraints and for systematic analyses of large numbers of lenses. Subroutines employing these results for the two power-law model and the results by Chae, Khersonsky, & Turnshek for the generalized single power-law mass model are made publicly available.

Kyu-Hyun Chae

2001-12-10T23:59:59.000Z

87

HerMES: A DEFICIT IN THE SURFACE BRIGHTNESS OF THE COSMIC INFRARED BACKGROUND DUE TO GALAXY CLUSTER GRAVITATIONAL LENSING  

SciTech Connect (OSTI)

We have observed four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measure a deficit of surface brightness within their central region after removing detected sources. We simulate the effects of instrumental sensitivity and resolution, the source population, and the lensing effect of the clusters to estimate the shape and amplitude of the deficit. The amplitude of the central deficit is a strong function of the surface density and flux distribution of the background sources. We find that for the current best fitting faint end number counts, and excellent lensing models, the most likely amplitude of the central deficit is the full intensity of the cosmic infrared background (CIB). Our measurement leads to a lower limit to the integrated total intensity of the CIB of I{sub 250{mu}m}>0.69{sub -0.03}{sup +0.03}(stat.){sub -0.06}{sup +0.11}(sys.) MJy sr{sup -1}, with more CIB possible from both low-redshift sources and from sources within the target clusters. It should be possible to observe this effect in existing high angular resolution data at other wavelengths where the CIB is bright, which would allow tests of models of the faint source component of the CIB.

Zemcov, M.; Cooray, A.; Bock, J.; Dowell, C. D.; Nguyen, H. T. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Blain, A. [Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Bethermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Conley, A.; Glenn, J. [Center for Astrophysics and Space Astronomy 389-UCB, University of Colorado, Boulder, CO 80309 (United States); Conversi, L. [Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, E-28691 Madrid (Spain); Farrah, D.; Oliver, S. J.; Roseboom, I. G. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Griffin, M. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Halpern, M.; Marsden, G. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Jullo, E.; Kneib, J.-P. [Aix-Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR7326, F-13388 Marseille (France); Richard, J., E-mail: zemcov@caltech.edu [Centre de Recherche Astronomique de Lyon, Universite Lyon 1, 9 avenue Charles Andre, F-69230 Saint-Genis Laval (France); and others

2013-06-01T23:59:59.000Z

88

TYPE Ia SUPERNOVA REMNANT SHELL AT z = 3.5 SEEN IN THE THREE SIGHTLINES TOWARD THE GRAVITATIONALLY LENSED QSO B1422+231  

SciTech Connect (OSTI)

Using the Subaru 8.2 m Telescope with the IRCS Echelle spectrograph, we obtained high-resolution (R = 10,000) near-infrared (1.01-1.38 {mu}m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z = 3.628) consisting of four known lensed images. We detected Mg II absorption lines at z = 3.54, which show a large variance of column densities ({approx}0.3 dex) and velocities ({approx}10 km s{sup -1}) between sightlines A and B with a projected separation of only 8.4h{sup -1}{sub 70} pc at that redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20 pc scale structure for the same z = 3.54 absorption system using optical spectra of images A and C. The observed systematic variances imply that the system is an expanding shell as originally suggested by Rauch et al. By combining the data for three sightlines, we managed to constrain the radius and expansion velocity of the shell ({approx}50-100 pc, 130 km s{sup -1}), concluding that the shell is truly a supernova remnant (SNR) rather than other types of shell objects, such as a giant H II region. We also detected strong Fe II absorption lines for this system, but with much broader Doppler width than that of {alpha}-element lines. We suggest that this Fe II absorption line originates in a localized Fe II-rich gas cloud that is not completely mixed with plowed ambient interstellar gas clouds showing other {alpha}-element low-ion absorption lines. Along with the Fe richness, we conclude that the SNR is produced by an SN Ia explosion.

Hamano, Satoshi; Kobayashi, Naoto [Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Kondo, Sohei [Koyama Astronomical Observatory, Kyoto-Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555 (Japan); Tsujimoto, Takuji [National Astronomical Observatory of Japan and Department of Astronomical Science, Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Okoshi, Katsuya [Faculty of Industrial Science and Technology, Tokyo University of Science, 102-1 Tomino, Oshamanbe, Hokkaido 049-3514 (Japan); Shigeyama, Toshikazu, E-mail: hamano@ioa.s.u-tokyo.ac.jp [Research Center for the Early Universe, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan)

2012-08-01T23:59:59.000Z

89

Optics in a nonlinear gravitational wave  

E-Print Network [OSTI]

Gravitational waves can act like gravitational lenses, affecting the observed positions, brightnesses, and redshifts of distant objects. Exact expressions for such effects are derived here, allowing for arbitrarily-moving sources and observers in the presence of plane-symmetric gravitational waves. The commonly-used predictions of linear perturbation theory are shown to be generically overshadowed---even for very weak gravitational waves---by nonlinear effects when considering observations of sufficiently distant sources; higher-order perturbative corrections involve secularly-growing terms which cannot necessarily be neglected. Even on more moderate scales where linear effects remain at least marginally dominant, nonlinear corrections are qualitatively different from their linear counterparts. There is a sense in which they can, for example, mimic the existence of a third type of gravitational wave polarization.

Harte, Abraham I

2015-01-01T23:59:59.000Z

90

Gamma-ray flaring activity from the gravitationally lensed blazar PKS 1830-211 observed by Fermi LAT  

E-Print Network [OSTI]

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope routinely detects the highly dust-absorbed, reddened, and MeV-peaked flat spectrum radio quasar PKS 1830-211 (z=2.507). Its apparent isotropic gamma-ray luminosity (E>100 MeV) averaged over $\\sim$ 3 years of observations and peaking on 2010 October 14/15 at 2.9 X 10^{50} erg s^{-1}, makes it among the brightest high-redshift Fermi blazars. No published model with a single lens can account for all of the observed characteristics of this complex system. Based on radio observations, one expects time delayed variability to follow about 25 days after a primary flare, with flux about a factor 1.5 less. Two large gamma-ray flares of PKS 1830-211 have been detected by the LAT in the considered period and no substantial evidence for such a delayed activity was found. This allows us to place a lower limit of about 6 on the gamma rays flux ratio between the two lensed images. Swift XRT observations from a dedicated Target of Opportunity program ...

Abdo, A A; Ajello, M; Allafort, A; Amin, M A; Baldini, L; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Blandford, R D; Bonamente, E; Borgland, A W; Bregeon, J; Brigida, M; Buehler, R; Bulmash, D; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Cavazzuti, E; Cecchi, C; Charles, E; Cheung, C C; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Corbet, R H D; Cutini, S; D'Ammando, F; de Angelis, A; de Palma, F; Dermer, C D; Drell, P S; Drlica-Wagner, A; Favuzzi, C; Finke, J; Focke, W B; Fukazawa, Y; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Grenier, I A; Grove, J E; Guiriec, S; Hadasch, D; Hayashida, M; Hays, E; Hughes, R E; Inoue, Y; Jackson, M S; Jogler, T; Jòhannesson, G; Johnson, A S; Kamae, T; Knödlseder, J; Kuss, M; Lande, J; Larsson, S; Latronico, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Mazziotta, M N; Mehault, J; Michelson, P F; Mizuno, T; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nemmen, R; Nuss, E; Ohno, M; Ohsugi, T; Paneque, D; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Reyes, L C; Ritz, S; Romoli, C; Roth, M; Parkinson, P M Saz; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Takahashi, H; Takeuchi, Y; Tanaka, T; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Tronconi, V; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Werner, M; Winer, B L; Wood, K S

2014-01-01T23:59:59.000Z

91

Systematic errors in the measurement of neutrino masses due to baryonic feedback processes: Prospects for stage IV lensing surveys  

E-Print Network [OSTI]

We examine the importance of baryonic feedback effects on the matter power spectrum on small scales, and the implications for the precise measurement of neutrino masses through gravitational weak lensing. Planned large galaxy surveys such as the Large Synoptic Sky Telescope (LSST) and Euclid are expected to measure the sum of neutrino masses to extremely high precision, sufficient to detect non-zero neutrino masses even in the minimal mass normal hierarchy. We show that weak lensing of galaxies while being a very good probe of neutrino masses, is extremely sensitive to baryonic feedback processes. We use publicly available results from the Overwhelmingly Large Simulations (OWLS) project to investigate the effects of active galactic nuclei feedback, the nature of the stellar initial mass function, and gas cooling rates, on the measured weak lensing shear power spectrum. Using the Fisher matrix formalism and priors from CMB+BAO data, we show that when one does not account for feedback, the measured neutrino mass may be substantially larger or smaller than the true mass, depending on the dominant feedback mechanism, with the mass error |\\Delta m_nu| often exceeding the mass m_nu itself. We also consider gravitational lensing of the cosmic microwave background (CMB) and show that it is not sensitive to baryonic feedback on scales l < 2000, although CMB experiments that aim for sensitivities sigma(m_nu) < 0.02 eV will need to include baryonic effects in modeling the CMB lensing potential. A combination of CMB lensing and galaxy lensing can help break the degeneracy between neutrino masses and baryonic feedback processes. We conclude that future large galaxy lensing surveys such as LSST and Euclid can only measure neutrino masses accurately if the matter power spectrum can be measured to similar accuracy.

Aravind Natarajan; Andrew R. Zentner; Nicholas Battaglia; Hy Trac

2014-09-04T23:59:59.000Z

92

Strong quantum violation of the gravitational weak equivalence principle by a non-Gaussian wave-packet  

E-Print Network [OSTI]

The weak equivalence principle of gravity is examined at the quantum level in two ways. First, the position detection probabilities of particles described by a non-Gaussian wave-packet projected upwards against gravity around the classical turning point and also around the point of initial projection are calculated. These probabilities exhibit mass-dependence at both these points, thereby reflecting the quantum violation of the weak equivalence principle. Secondly, the mean arrival time of freely falling particles is calculated using the quantum probability current, which also turns out to be mass dependent. Such a mass-dependence is shown to be enhanced by increasing the non-Gaussianity parameter of the wave packet, thus signifying a stronger violation of the weak equivalence principle through a greater departure from Gaussianity of the initial wave packet. The mass-dependence of both the position detection probabilities and the mean arrival time vanish in the limit of large mass. Thus, compatibility between the weak equivalence principle and quantum mechanics is recovered in the macroscopic limit of the latter. A selection of Bohm trajectories is exhibited to illustrate these features in the free fall case.

P. Chowdhury; D. Home; A. S. Majumdar; S. V. Mousavi; M. R. Mozaffari; S. Sinha

2011-12-27T23:59:59.000Z

93

Energy and angular momentum of the weak gravitational waves on the Schwarzschild background -- quasilocal gauge-invariant formulation  

E-Print Network [OSTI]

It is shown that the axial and polar perturbations of the spherically symmetric black hole can be described in a gauge-invariant way. The reduced phase space describing gravitational waves outside of the horizon is described by the gauge-invariant quantities. Both degrees of freedom fulfill generalized scalar wave equation. For the axial degree of freedom the radial part of the equation corresponds to the Regge-Wheeler result (Phys. Rev. 108, 1063-1069 (1957)) and for the polar one we get Zerilli result (Phys. Rev. D2, 2141-2160 (1970)), see also Chandrasekhar (The Mathematical Theory of Black Holes,(Clarendon Press Oxford, 1983)), Moncrief (Annals of Physics 88, 323-342 (1974)) for both. An important ingredient of the analysis is the concept of quasilocality which does duty for the separation of the angular variables in the usual approach. Moreover, there is no need to represent perturbations by normal modes (with time dependence $\\exp(-ikt)$), we have fields in spacetime and the Cauchy problem for them is well defined outside of the horizon. The reduced symplectic structure explains the origin of the axial and polar invariants. It allows to introduce an energy and angular momentum for the gravitational waves which is invariant with respect to the gauge transformations. Both generators represent quadratic approximation of the ADM nonlinear formulae in terms of the perturbations of the Schwarzschild metric. We also discuss the boundary-initial value problem for the linearized Einstein equations on a Schwarzschild background outside of the horizon.

Jacek Jezierski

1998-01-20T23:59:59.000Z

94

Copenhagen Quantum Mechanics Emerges from a Deterministic Schroedinger Theory in 11 Dimensional Spacetime Including Weak Field Gravitation  

E-Print Network [OSTI]

We construct a world model consisting of a matter field living in 4 dimensional spacetime and a gravitational field living in 11 dimensional spacetime. The seven hidden dimensions are compactified within a radius estimated by reproducing the particle - wave characteristic of diffraction experiments. In the presence of matter fields the gravitational field develops localized modes with elementary excitations called gravonons which are induced by the sources (massive particles). The final world model treated here contains only gravonons and a scalar matter field. The solution of the Schroedinger equation for the world model yields matter fields which are localized in the 4 dimensional subspace. The localization has the following properties: (i) There is a chooser mechanism for the selection of the localization site. (ii) The chooser selects one site on the basis of minor energy differences and differences in the gravonon structure between the sites, which appear statistical. (iii) The changes from one localization site to a neighbouring one take place in a telegraph-signal like manner. (iv) The times at which telegraph like jumps occur dependent on subtleties of the gravonon structure which appear statistical. (v) The fact that the dynamical law acts in the configuration space of fields living in 11 dimensional spacetime lets the events observed in 4 dimensional spacetime appear non-local. In this way the phenomenology of Copenhagen quantum mechanics is obtained without the need of introducing the process of collapse and a probabilistic interpretation of the wave function. Operators defining observables need not be introduced. All experimental findings are explained in a deterministic way as a consequence of the time development of the wave function in configuration space according to Schroedinger's equation.

Gerold Doyen; Deiana Drakova

2014-08-12T23:59:59.000Z

95

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

96

Maps of CMB lensing deflection from N-body simulations in Coupled Dark Energy Cosmologies  

SciTech Connect (OSTI)

We produce lensing potential and deflection-angle maps in order to simulate the weak gravitational lensing of the Cosmic Microwave Background (CMB) via ray-tracing through the COupled Dark Energy Cosmological Simulations (CoDECS), the largest suite of N-body simulations to date for interacting Dark Energy cosmologies. The constructed maps faithfully reflect the N-body cosmic structures on a range of scales going from the arcminute to the degree scale, limited only by the resolution and extension of the simulations. We investigate the variation of the lensing pattern due to the underlying Dark Energy (DE) dynamics, characterised by different background and perturbation behaviours as a consequence of the interaction between the DE field and Cold Dark Matter (CDM). In particular, we study in detail the results from three cosmological models differing in the background and perturbations evolution at the epoch in which the lensing cross section is most effective, corresponding to a redshift of ? 1, with the purpose to isolate their imprints in the lensing observables, regardless of the compatibility of these models with present constraints. The scenarios investigated here include a reference ?CDM cosmology, a standard coupled DE (cDE) scenario, and a ''bouncing'' cDE scenario. For the standard cDE scenario, we find that typical differences in the lensing potential result from two effects: the enhanced growth of linear CDM density fluctuations with respect to the ?CDM case, and the modified nonlinear dynamics of collapsed structures induced by the DE-CDM interaction. As a consequence, CMB lensing highlights the DE impact in the cosmological expansion, even in the degenerate case where the amplitude of the linear matter density perturbations, parametrised through ?{sub 8}, is the same in both the standard cDE and ?CDM cosmologies. For the ''bouncing'' scenario, we find that the two opposite behaviours of the lens density contrast and of the matter abundance lead to a counter-intuitive effect, making the power of the lensing signal in this model lower by 10% than in the ?CDM scenario. Moreover, we compare the behaviour of CDM and baryons in CoDECS separately, in order to isolate effects coming from the coupling with the DE component. We find that, in the bouncing scenario, baryons show an opposite trend with respect to CDM, due to the coupling of the latter with the DE component. These results confirm the relevance of CMB lensing as a probe for DE at the early stages of cosmic acceleration, and demonstrate the reliability of N-body based large scale CMB lensing simulations in the context of DE studies.

Carbone, Carmelita [INAF – Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate (Italy); Baldi, Marco [Dipartimento di Fisica e Astronomia, Università di Bologna, Viale B. Pichat 6/2, I-40127 Bologna (Italy); Pettorino, Valeria [Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, 24 quai Ernest Ansermet, CH–1211 Genève 4 (Switzerland); Baccigalupi, Carlo, E-mail: carmelita.carbone@brera.inaf.it, E-mail: marco.baldi5@unibo.it, E-mail: valeria.pettorino@unige.ch, E-mail: bacci@sissa.it [SISSA, Via Bonomea 265, Trieste, I-34136 (Italy)

2013-09-01T23:59:59.000Z

97

A TWO-YEAR TIME DELAY FOR THE LENSED QUASAR SDSS J1029+2623  

SciTech Connect (OSTI)

We present 279 epochs of optical monitoring data spanning 5.4 years from 2007 January to 2012 June for the largest image separation (22.''6) gravitationally lensed quasar, SDSS J1029+2623. We find that image A leads the images B and C by {Delta} t {sub AB} = (744 {+-} 10) days (90% confidence); the uncertainty includes both statistical uncertainties and systematic differences due to the choice of models. With only a {approx}1% fractional error, the interpretation of the delay is limited primarily by cosmic variance due to fluctuations in the mean line-of-sight density. We cannot separate the fainter image C from image B, but since image C trails image B by only 2-3 days in all models, the estimate of the time delay between images A and B is little affected by combining the fluxes of images B and C. There is weak evidence for a low level of microlensing, perhaps created by the small galaxy responsible for the flux ratio anomaly in this system. Interpreting the delay depends on better constraining the shape of the gravitational potential using the lensed host galaxy, other lensed arcs, and the structure of the X-ray emission.

Fohlmeister, Janine; Wambsganss, Joachim [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstr. 12-14, D-69120 Heidelberg (Germany)] [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstr. 12-14, D-69120 Heidelberg (Germany); Kochanek, Christopher S. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)] [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Falco, Emilio E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Oguri, Masamune [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)] [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Dai, Xinyu [Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States)] [Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States)

2013-02-20T23:59:59.000Z

98

A Consistent Picture Emerges: A Compact X-ray Continuum Emission Region in the Gravitationally Lensed Quasar SDSS J0924+0219  

E-Print Network [OSTI]

We analyze the optical, UV, and X-ray microlensing variability of the lensed quasar SDSS J0924+0219 using six epochs of Chandra data in two energy bands (spanning 0.4-8.0 keV, or 1-20 keV in the quasar rest frame), 10 epochs of F275W (rest-frame 1089A) Hubble Space Telescope data, and high-cadence R-band (rest-frame 2770A) monitoring spanning eleven years. Our joint analysis provides robust constraints on the extent of the X-ray continuum emission region and the projected area of the accretion disk. The best-fit half-light radius of the soft X-ray continuum emission region is between 5x10^13 and 10^15 cm, and we find an upper limit of 10^15 cm for the hard X-rays. The best-fit soft-band size is about 13 times smaller than the optical size, and roughly 7 GM_BH/c^2 for a 2.8x10^8 M_sol black hole, similar to the results for other systems. We find that the UV emitting region falls in between the optical and X-ray emitting regions at 10^14 cm optical size is significant...

MacLeod, Chelsea L; Mosquera, A; Kochanek, C; Tewes, M; Courbin, F; Meylan, G; Chen, B; Dai, X; Chartas, G

2015-01-01T23:59:59.000Z

99

Wide-Field Lensing Mass Maps from DES Science Verification Data  

E-Print Network [OSTI]

Weak gravitational lensing allows one to reconstruct the spatial distribution of the projected mass density across the sky. These "mass maps" provide a powerful tool for studying cosmology as they probe both luminous and dark matter. In this paper, we present a weak lensing mass map reconstructed from shear measurements in a 139 deg^2 area from the Dark Energy Survey (DES) Science Verification (SV) data overlapping with the South Pole Telescope survey. We compare the distribution of mass with that of the foreground distribution of galaxies and clusters. The overdensities in the reconstructed map correlate well with the distribution of optically detected clusters. Cross-correlating the mass map with the foreground galaxies from the same DES SV data gives results consistent with mock catalogs that include the primary sources of statistical uncertainties in the galaxy, lensing, and photo-z catalogs. The statistical significance of the cross-correlation is at the 6.8 sigma level with 20 arcminute smoothing. A maj...

Vikram, V; Jain, B; Bacon, D; Amara, A; Becker, M; Bernstein, G; Bonnett, C; Bridle, S; Brout, D; Busha, M; Frieman, J; Gaztanaga, E; Hartley, W; Jarvis, M; Kacprzak, T; Lahav, O; Leistedt, B; Lin, H; Melchior, P; Peiris, H; Rozo, E; Rykoff, E; Sanchez, C; Sheldon, E; Troxel, M; Wechsler, R; Zuntz, J; Abbott, T; Abdalla, F B; Armstrong, R; Banerji, M; Bauer, A H; Benoit-Levy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; Castander, F J; Crocce, M; D'Andrea, C B; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Dietrich, J P; Cunha, C E; Estrada, J; Evrard, A E; Neto, A Fausti; Fernandez, E; Flaugher, B; Fosalba, P; Gerdes, D; Gruen, D; Gruendl, R A; Honscheid, K; James, D; Kent, S; Kuehn, K; Kuropatkin, N; Li, T S; Maia, M A G; Makler, M; March, M; Marshall, J; Martini, Paul; Merritt, K W; Miller, C J; Miquel, R; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Scarpine, V; Sevilla, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Thomas, D; Walker, A R; Weller, J

2015-01-01T23:59:59.000Z

100

Diagnosing multiplicative error by lensing magnification of type Ia supernovae  

E-Print Network [OSTI]

Weak lensing causes spatially coherent fluctuations in flux of type Ia supernovae (SNe Ia). This lensing magnification allows for weak lensing measurement independent of cosmic shear. It is free of shape measurement errors associated with cosmic shear and can therefore be used to diagnose and calibrate multiplicative error. Although this lensing magnification is difficult to measure accurately in auto correlation, its cross correlation with cosmic shear and galaxy distribution in overlapping area can be measured to significantly higher accuracy. Therefore these cross correlations can put useful constraint on multiplicative error, and the obtained constraint is free of cosmic variance in weak lensing field. We present two methods implementing this idea and estimate their performances. We find that, with $\\sim 1$ million SNe Ia that can be achieved by the proposed D2k survey with the LSST telescope (Zhan et al. 2008), multiplicative error of $\\sim 0.5\\%$ for source galaxies at $z_s\\sim 1$ can be detected and la...

Zhang, Pengjie

2015-01-01T23:59:59.000Z

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.
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to obtain the most current and comprehensive results.


101

Gravitational Correction in Neutrino Oscillations  

E-Print Network [OSTI]

We investigate the quantum mechanical oscillations of neutrinos propagating in weak gravitational field. The correction to the result in the flat space-time is derived.

Yasufumi Kojima

1996-12-17T23:59:59.000Z

102

analysis identifies weak: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

parameter estimation via weak lensing, with an emphasis on the equation of state of dark energy. P. G. Castro; A. F. Heavens; T. D. Kitching 2005-07-20 5 Composite Weak...

103

Gravitation Physics at BGPL  

E-Print Network [OSTI]

We report progress on a program of gravitational physics experiments using cryogenic torsion pendula undergoing large-amplitude torsion oscillation. This program includes tests of the gravitational inverse square law and of the weak equivalence principle. Here we describe our ongoing search for inverse-square-law violation at a strength down to $10^{-5}$ of standard gravity. The low-vibration environment provided by the Battelle Gravitation Physics Laboratory (BGPL) is uniquely suited to this study.

P. E. Boynton; R. M. Bonicalzi; A. M. Kalet; A. M. Kleczewski; J. K. Lingwood; K. J. McKenney; M. W. Moore; J. H. Steffen; E. C. Berg; W. D. Cross; R. D. Newman; R. E. Gephart

2006-09-21T23:59:59.000Z

104

Multipole Expansion Model in Gravitational Lensing  

E-Print Network [OSTI]

Non-transparent models of multipole expansion model and two point-mass model are analyzed from the catastrophe theory. Singularity behaviours of $2^n$-pole moments are discussed. We apply these models to triple quasar PG1115+080 and compare with the typical transparent model, softened power law spheroids. Multipole expansion model gives the best fit among them.

T. Fukuyama; Y. Kakigi; T. Okamura

1997-01-31T23:59:59.000Z

105

Gravitational LensingGravitational Lensing Physics 343, Lecture 11Physics 343, Lecture 11  

E-Print Network [OSTI]

emission free from differential extinction concerns Biggs et al., 1999 #12;Time DelaysTime Delays Biggs et

Baker, Andrew J.

106

SPATIALLY RESOLVED HST GRISM SPECTROSCOPY OF A LENSED EMISSION LINE GALAXY AT z {approx} 1  

SciTech Connect (OSTI)

We take advantage of gravitational lensing amplification by A1689 (z 0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i{sub 775} = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of Almost-Equal-To 4.5. Several Balmer emission lines (ELs) detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M{sub *} Almost-Equal-To 2 Multiplication-Sign 10{sup 9} M{sub Sun }) with a high specific star formation rate ( Almost-Equal-To 20 Gyr{sup -1}). From the blue ELs we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H) = 8.8 {+-} 0.2). We break the continuous line-emitting region of this giant arc into seven {approx}1 kpc bins (intrinsic size) and measure a variety of metallicity-dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by {approx}1 kpc have a placement on the blue H II region excitation diagram with f ([O III])/f (H{beta}) and f ([Ne III])/f (H{beta}) that can be fitted by an active galactic nucleus (AGN). This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction.

Frye, Brenda L. [Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Hurley, Mairead [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Bowen, David V. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08540 (United States); Meurer, Gerhardt [International Centre for Radio Astronomy Research, The University of Western Australia M468, 35 Stirling Highway, Crawley, WA 6009 (Australia); Sharon, Keren [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States); Straughn, Amber [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Coe, Dan [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Broadhurst, Tom [Ikerbasque, Basque Foundation for Science, E-48011 Bilbao (Spain); Guhathakurta, Puragra, E-mail: bfrye@as.arizona.edu [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2012-07-20T23:59:59.000Z

107

Neutrino optics and oscillations in gravitational fields  

E-Print Network [OSTI]

We study the propagation of neutrinos in gravitational fields using wave functions that are exact to first order in the metric deviation. For illustrative purposes, the geometrical background is represented by the Lense-Thirring metric. We derive explicit expressions for neutrino deflection, helicity transitions, flavor oscillations and oscillation Hamiltonian.

G. Lambiase; G. Papini; R. Punzi; G. Scarpetta

2005-03-07T23:59:59.000Z

108

Angular momentum effects in weak gravitational fields  

E-Print Network [OSTI]

It is shown that, contrary to what is normally expected, it is possible to have angular momentum effects on the geometry of space time at the laboratory scale, much bigger than the purely Newtonian effects. This is due to the fact that the ratio between the angular momentum of a body and its mass, expressed as a length, is easily greater than the mass itself, again expressed as a length.

A. Tartaglia

2002-01-02T23:59:59.000Z

109

Quantum Mechanics and Gravitation  

E-Print Network [OSTI]

In summer 1999 an experiment at ILL, Grenoble was conducted. So-called ultra-cold neutrons (UCN) were trapped in the vertical direction between the Fermi-potential of a smooth mirror below and the gravitational potential of the earth above [Ne00, Ru00]. If quantum mechanics turns out to be a sufficiently correct description of the phenomena in the regime of classical, weak gravitation, one should observe the forming of quantized bound states in the vertical direction above a mirror. Already in a simplified view, the data of the experiment provides strong evidence for the existence of such gravitationally bound quantized states. A successful quantum-mechanical description would then provide a convincing argument, that the socalled first quantization can be used for gravitation as an interaction potential, as this is widely expected. Furthermore, looking at the characteristic length scales of about 10 mikron of such bound states formed by UCN, one sees, that a complete quantum mechanical description of this experiment additionally would enable one to check for possible modifications of Newtonian gravitation on distance scales being one order of magnitude below currently available tests [Ad00]. The work presented here deals mainly with the development of a quantum mechanical description of the experiment.

A. Westphal

2003-04-08T23:59:59.000Z

110

Hollow lensing duct  

DOE Patents [OSTI]

A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Bibeau, Camille (Dublin, CA); Mitchell, Scott (Tracy, CA); Lang, John (Pleasanton, CA); Maderas, Dennis (Pleasanton, CA); Speth, Joel (San Ramon, CA); Payne, Stephen A. (Castro Valley, CA)

2000-01-01T23:59:59.000Z

111

LAGEOS-type Satellites in Critical Supplementary Orbit Configuration and the Lense-Thirring Effect Detection  

E-Print Network [OSTI]

In this paper we analyze quantitatively the concept of LAGEOS--type satellites in critical supplementary orbit configuration (CSOC) which has proven capable of yielding various observables for many tests of General Relativity in the terrestrial gravitational field, with particular emphasis on the measurement of the Lense--Thirring effect.

Lorenzo Iorio; David M. Lucchesi

2003-05-20T23:59:59.000Z

112

LAGEOS--type Satellites in Critical Supplementary Orbit Configuration and the Lense--Thirring Effect Detection  

E-Print Network [OSTI]

In this paper we analyze quantitatively the concept of LAGEOS--type satellites in critical supplementary orbit configuration (CSOC) which has proven capable of yielding various observables for many tests of General Relativity in the terrestrial gravitational field, with particular emphasis on the measurement of the Lense--Thirring effect.

Iorio, L; Iorio, Lorenzo; Lucchesi, David M.

2003-01-01T23:59:59.000Z

113

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

114

The Extragalactic Lens VLBI Imaging Survey (ELVIS) : investigating galaxy cores and black holes with gravitational lens central images  

E-Print Network [OSTI]

This thesis describes the Extragalactic Lens VLBI Imaging Survey (ELVIS), a search for central images in gravitational lenses. We present the first four ELVIS targets, for which we have radio VLBI observations with resolutions ...

Boyce, Edward R

2006-01-01T23:59:59.000Z

115

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

116

Acceleration of low energy charged particles by gravitational waves  

E-Print Network [OSTI]

The acceleration of charged particles in the presence of a magnetic field and gravitational waves is under consideration. It is shown that the weak gravitational waves can cause the acceleration of low energy particles under appropriate conditions. Such conditions may be satisfied close to the source of the gravitational waves if the magnetized plasma is in a turbulent state.

G. Voyatzis; L. Vlahos; S. Ichtiaroglou; D. Papadopoulos

2005-12-07T23:59:59.000Z

117

CMB-Cluster Lensing  

E-Print Network [OSTI]

Clusters of galaxies are powerful cosmological probes, particularly if their masses can be determined. One possibility for mass determination is to study the cosmic microwave background (CMB) on small angular scales and observe deviations from a pure gradient due to lensing of massive clusters. I show that, neglecting contamination, this technique has the power to determine cluster masses very accurately, in agreement with estimates by Seljak and Zaldarriaga (1999). However, the intrinsic small scale structure of the CMB significantly degrades this power. The resulting mass constraints are useless unless one imposes a prior on the concentration parameter c. With even a modest prior on c, an ambitious CMB experiment (0.5' resolution and 1 microK per pixel) could determine masses of high redshift (z>0.5) clusters with ~ 30% accuracy.

Scott Dodelson

2004-02-12T23:59:59.000Z

118

Class B0631+519: Last of the Class Lenses  

SciTech Connect (OSTI)

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,

2005-05-31T23:59:59.000Z

119

Gravitational waves from gravitational collapse  

SciTech Connect (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

120

Analytic Models of Plausible Gravitational Lens Potentials  

SciTech Connect (OSTI)

Gravitational lenses on galaxy scales are plausibly modeled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sersic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasizing that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential.We also provide analytic formulae for the lens potentials of Sersic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modeled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses.

Baltz, Edward A.; Marshall, Phil; Oguri, Masamune

2007-05-04T23:59:59.000Z

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

Analytic models of plausible gravitational lens potentials  

SciTech Connect (OSTI)

Gravitational lenses on galaxy scales are plausibly modelled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sersic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasising that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential. We also provide analytic formulae for the lens potentials of Sersic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modelled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses.

Baltz, Edward A.; Marshall, Phil; Oguri, Masamune, E-mail: eabaltz@slac.stanford.edu, E-mail: pjm@physics.ucsb.edu, E-mail: oguri@slac.stanford.edu [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, PO Box 20450, MS29, Stanford, CA 94309 (United States)] [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, PO Box 20450, MS29, Stanford, CA 94309 (United States)

2009-01-15T23:59:59.000Z

122

Science, Optics and You: Light and Lenses  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

with Lenses, students will be encouraged to use each of the lenses supplied in the Science, Optics and You package. Students will look at different images, use flashlights to...

123

A Comparison of Cosmological Models Using Time Delay Lenses  

E-Print Network [OSTI]

The use of time-delay gravitational lenses to examine the cosmological expansion introduces a new standard ruler with which to test theoretical models. The sample suitable for this kind of work now includes 12 lens systems, which have thus far been used solely for optimizing the parameters of $\\Lambda$CDM. In this paper, we broaden the base of support for this new, important cosmic probe by using these observations to carry out a one-on-one comparison between {\\it competing} models. The currently available sample indicates a likelihood of $\\sim 70-80%$ that the $R_{\\rm h}=ct$ Universe is the correct cosmology versus $\\sim 20-30%$ for the standard model. This possibly interesting result reinforces the need to greatly expand the sample of time-delay lenses, e.g., with the successful implementation of the Dark Energy Survey, the VST ATLAS survey, and the Large Synoptic Survey Telescope. In anticipation of a greatly expanded catalog of time-delay lenses identified with these surveys, we have produced synthetic sa...

Wei, Jun-Jie; Melia, Fulvio

2014-01-01T23:59:59.000Z

124

Possible Enhancement of High Frequency Gravitational Waves  

E-Print Network [OSTI]

We study the tensor perturbations in a class of non-local, purely gravitational models which naturally end inflation in a distinctive phase of oscillations with slight and short violations of the weak energy condition. We find the usual generic form for the tensor power spectrum. The presence of the oscillatory phase leads to an enhancement of gravitational waves with frequencies somewhat less than 10^{10} Hz.

Maria G. Romania; N. C. Tsamis; R. P. Woodard

2011-03-05T23:59:59.000Z

125

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 the...

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

2008-01-01T23:59:59.000Z

126

Hubble constant from lensing in plasma-redshift cosmology, and intrinsic redshift of quasars  

E-Print Network [OSTI]

In a series of articles, we have shown that the newly discovered plasma-redshift cosmology gives a simpler, more accurate and consistent explanation of many cosmological phenomena than the big-bang cosmology. The SNe Ia observations are in better agreement with the magnitude-redshift relation predicted by the plasma redshift than that predicted by the multi-parameter big-bang cosmology. No deceleration or expansion parameters are needed. The plasma-redshift cosmology is flat and quasi-static on a large scale. The Hubble constant is no longer an expansion parameter, but is instead a measure of the average electron density along the line of sight towards an object. Perusal of the SNe Ia data and quasar data has shown that there is no time dilation. The conventional estimates of the Hubble constant from gravitational lensing observations use the big-bang cosmology for interpreting the observations. This has lead to a large spread and discordant estimates of the Hubble constant. The purpose of the present article is to show that the gravitational lensing observations are in agreement with the plasma-redshift cosmology, and to show how to evaluate the lensing observations based on the new plasma-redshift cosmology. The lensing observations also indicate that the quasars have large intrinsic redshifts.

Ari Brynjolfsson

2004-12-02T23:59:59.000Z

127

Gravitational microlensing results from MACHO  

SciTech Connect (OSTI)

The MACHO project is searching for dark qter inthe form of massive compact haio objects (Machos), by monitoring the brightness of millions of stars in the Magellanic Clouds to search for gravitational microlensing events. Analysis of our 1st 2.3 years of data for 8.5 million stars in the LMC yields 8 candidate microlensing events, well in excess of the {approx} 1 event expected from lensing by known low-mass stars. The event timescales range from 34 to 145 days, and the estimated optical depth is N 2x10{sup -7}, about half of that expected from a `standard` halo. Likelihood analysis indicates the typical lens mass is 0.5{sup +0.3}{sub -0.2}M{sub {circle_dot}}, suggesting they may be old white dwarfs.

Alcock, C.; MACHO Collaboration

1996-09-01T23:59:59.000Z

128

Modified Entropic Gravitation in Superconductors  

E-Print Network [OSTI]

Verlinde recently developed a theoretical account of gravitation in terms of an entropic force. The central element in Verlinde's derivation is information and its relation with entropy through the holographic principle. The application of this approach to the case of superconductors requires to take into account that information associated with superconductor's quantum vacuum energy is not stored on Planck size surface elements, but in four volume cells with Planck-Einstein size. This has profound consequences on the type of gravitational force generated by the quantum vacuum condensate in superconductors, which is closely related with the cosmological repulsive acceleration responsible for the accelerated expansion of the Universe. Remarkably this new gravitational type force depends on the level of breaking of the weak equivalence principle for cooper pairs in a given superconducting material, which was previously derived by the author starting from similar principles. It is also shown that this new gravitational force can be interpreted as a surface force. The experimental detection of this new repulsive gravitational-type force appears to be challenging.

Clovis Jacinto de Matos

2011-08-19T23:59:59.000Z

129

Galaxy density profiles and shapes -- II. selection biases in strong lensing surveys  

E-Print Network [OSTI]

[Abridged] Many current and future astronomical surveys will rely on samples of strong gravitational lens systems to draw conclusions about galaxy mass distributions. We use a new strong lensing pipeline (presented in Paper I of this series) to explore selection biases that may cause the population of strong lensing systems to differ from the general galaxy population. Our focus is on point-source lensing by early-type galaxies with two mass components (stellar and dark matter) that have a variety of density profiles and shapes motivated by observational and theoretical studies of galaxy properties. We seek not only to quantify but also to understand the physics behind selection biases related to: galaxy mass, orientation and shape; dark matter profile parameters such as inner slope and concentration; and adiabatic contraction. We study how all of these properties affect the lensing Einstein radius, total cross-section, quad/double ratio, and image separation distribution. We find significant (factors of several) selection biases with mass; orientation, for a given galaxy shape at fixed mass; cusped dark matter profile inner slope and concentration; concentration of the stellar and dark matter deprojected Sersic models. Interestingly, the intrinsic shape of a galaxy does not strongly influence its lensing cross-section when we average over viewing angles. Our results are an important first step towards understanding how strong lens systems relate to the general galaxy population.

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

2009-06-18T23:59:59.000Z

130

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 nonspinning intermediate mass black holes in the total mass range 100–450??M? and with the component mass ratios between 1?1 ...

Barsotti, Lisa

131

Plasma waves driven by gravitational waves in an expanding universe  

E-Print Network [OSTI]

In a Friedmann-Robertson-Walker (FRW) cosmological model with zero spatial curvature, we consider the interaction of the gravitational waves with the plasma in the presence of a weak magnetic field. Using the relativistic hydromagnetic equations it is verified that large amplitude magnetosonic waves are excited, assuming that both, the gravitational field and the weak magnetic field do not break the homogeneity and isotropy of the considered FRW spacetime.

D. B. Papadopoulos

2002-05-22T23:59:59.000Z

132

Gravitational Lens Modeling with Genetic Algorithms and Particle Swarm Optimizers  

E-Print Network [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 automa...

Rogers, Adam

2011-01-01T23:59:59.000Z

133

Retrieving the 3D matter power spectrum and galaxy biasing parameters from lensing tomography  

E-Print Network [OSTI]

With the availability of galaxy distance indicators in weak lensing surveys, lensing tomography can basically be harnessed to constrain the spatial 3D matter power spectrum over a range in redshift and physical scale. Furthermore, by adding galaxy-galaxy lensing and galaxy clustering this can be extended to probe the 3D galaxy-matter and galaxy-galaxy power spectrum or, alternatively, galaxy biasing parameters. To achieve this aim, this paper introduces and discusses minimum variance estimators and a more general Bayesian approach to statistically invert a set of noisy tomography 2-point correlation functions, measured within a confined opening angle. Both methods are constructed such that they probe deviations of the 3D power spectrum from a fiducial power spectrum. Thereby a direct comparison of theory and data is achieved, the physical scale and redshift of deviations can in principle be identified. By devising a new Monte Carlo technique the measurement noise in the correlators is quantified for a fiducia...

Simon, Patrick

2012-01-01T23:59:59.000Z

134

Lower Limit to the Scale of an Effective Theory of Gravitation  

E-Print Network [OSTI]

We consider a linearized, effective quantum theory of gravitation in which gravity weakens at energies higher than ~10^-3 eV in order to accommodate the apparent smallness of the cosmological constant. Such a theory predicts departures from the static Newtonian inverse-square force law on distances below ~0.05 mm. However, we show that such a modification also leads to changes in the long-range behavior of gravity and is inconsistent with observed gravitational lenses.

R. R. Caldwell; Daniel Grin

2008-02-26T23:59:59.000Z

135

Noise properties of gravitational lens mass reconstruction  

E-Print Network [OSTI]

Gravitational lensing is potentially able to observe mass-selected halos, and to measure the projected cluster mass function. An optimal mass-selection requires a quantitative understanding of the noise behavior in mass maps. This paper is an analysis of the noise properties in mass maps reconstructed using a maximum likelihood method. The noise power spectrum and the mass error bars are derived as a straightforward extension of the Kaiser & Squires (1993) algorithm to the case of a correlated noise. A very good agreement is found between these calculations and the noise properties observed in maximum likelihood mass reconstructions limited to simulated non-critical clusters of galaxies. In a second part, I show that the statistic of peaks in the noise follows accurately the peak statistics of a two-dimensional Gaussian random field (using the BBKS technics) if the smoothing aperture contains enough galaxies. This analysis provides a procedure to derive the significance of any mass peak as a function of its amplitude and its profile. It is demonstrated that, to a very good approximation, a mass map is the sum of the lensing signal plus a 2D gaussian random noise, which means that a detailled quantitative analysis of the structures in mass maps can be done. A direct application is the measurement of the projected mass function in wide field lensing surveys, down to small mass halos which are individually undetectable, this is the subject of a forthcoming work.

L. Van Waerbeke

1999-09-09T23:59:59.000Z

136

MODEL-FREE MULTI-PROBE LENSING RECONSTRUCTION OF CLUSTER MASS PROFILES  

SciTech Connect (OSTI)

Lens magnification by galaxy clusters induces characteristic spatial variations in the number counts of background sources, amplifying their observed fluxes and expanding the area of sky, the net effect of which, known as magnification bias, depends on the intrinsic faint-end slope of the source luminosity function. The bias is strongly negative for red galaxies, dominated by the geometric area distortion, whereas it is mildly positive for blue galaxies, enhancing the blue counts toward the cluster center. We generalize the Bayesian approach of Umetsu et al. for reconstructing projected cluster mass profiles, by incorporating multiple populations of background sources for magnification-bias measurements and combining them with complementary lens-distortion measurements, effectively breaking the mass-sheet degeneracy and improving the statistical precision of cluster mass measurements. The approach can be further extended to include strong-lensing projected mass estimates, thus allowing for non-parametric absolute mass determinations in both the weak and strong regimes. We apply this method to our recent CLASH lensing measurements of MACS J1206.2-0847, and demonstrate how combining multi-probe lensing constraints can improve the reconstruction of cluster mass profiles. This method will also be useful for a stacked lensing analysis, combining all lensing-related effects in the cluster regime, for a definitive determination of the averaged mass profile.

Umetsu, Keiichi [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)

2013-05-20T23:59:59.000Z

137

Integral field spectroscopy of four lensed quasars: analysis of their neighborhood and evidence for microlensing  

E-Print Network [OSTI]

CONTEXT: Gravitationally lensed quasars constitute an independent tool to derive H0 through time-delays; they offer as well the opportunity to study the mass distribution and interstellar medium of their lensing galaxies and, through microlensing they also allow one to study details of the emitting source. AIMS: For such studies, one needs to have an excellent knowledge of the close environment of the lensed images in order to model the lensing potential: this means observational data over a large field-of-view and spectroscopy at high spatial resolution. METHODS: We present VIMOS integral field observations around four lensed quasars: HE 0230-2130, RX J0911.4+0551, H 1413+117 and B 1359+154. Using the low, medium and high resolution modes, we study the quasar images and the quasar environments, as well as provide a detailed report of the data reduction. RESULTS: Comparison between the quasar spectra of the different images reveals differences for HE 0230-2130, RX J0911.4+0551 and H 1413+117: flux ratios between the images of the same quasar are different when measured in the emission lines and in the continuum. We have also measured the redshifts of galaxies in the neighborhood of HE 0230-2130 and RX J0911.4+0551 which possibly contribute to the total lensing potential. CONCLUSIONS: A careful analysis reveals that microlensing is the most natural explanation for the (de)magnification of the continuum emitting region of the background sources. In HE 0230-2130, image D is likely to be affected by microlensing magnification; in RX J0911.4+0551, images A1 and A3 are likely to be modified by microlensing de-magnification and in H 1413+117, at least image D is affected by microlensing.

T. Anguita; C. Faure; A. Yonehara; J. Wambsganss; J. -P. Kneib; G. Covone; D. Alloin

2008-02-04T23:59:59.000Z

138

Cosmography with cluster strong lensing  

E-Print Network [OSTI]

By stacking an ensemble of strong lensing clusters, we demonstrate the feasibility of placing constraints on the dark energy equation of state. This is achieved by using multiple images of sources at two or more distinct redshift planes. The sample of smooth clusters in our simulations is based on observations of massive clusters and the distribution of background galaxies is constructed using the Hubble Deep Field. Our source distribution reproduces the observed redshift distribution of multiply imaged sources in Abell 1689. The cosmology recovery depends on the number of image families with known spectroscopic redshifts and the number of stacked clusters. Our simulations suggest that constraints comparable to those derived from other competing established techniques on a constant dark energy equation of state can be obtained using 10 to 40 clusters with 5 or more families of multiple images. We have also studied the observational errors in the image redshifts and positions. We find that spectroscopic redshifts and high resolution {\\it Hubble Space Telescope} images are required to eliminate confidence contour relaxation relative to the ideal case in our simulations. This suggests that the dark energy equation of state, and other cosmological parameters, can be constrained with existing {\\it Hubble Space Telescope} images of lensing clusters coupled with dedicated ground-based arc spectroscopy.

James Gilmore; Priyamvada Natarajan

2009-05-29T23:59:59.000Z

139

Electromagnetic radiation by gravitating bodies  

E-Print Network [OSTI]

Gravitating bodies in motion, regardless of their constitution, always produce electromagnetic radiation in the form of photon pairs. This phenomenon is an analog of the radiation caused by the motion of dielectric (or magnetic) bodies. It is a member of a wide class of phenomena named dynamical Casimir effects, and it may be viewed as the squeezing of the electromagnetic vacuum. Production of photon pairs is a purely quantum-mechanical effect. Unfortunately, as we show, the emitted radiation is extremely weak as compared to radiation produced by other mechanisms.

Iwo Bialynicki-Birula; Zofia Bialynicka-Birula

2008-05-06T23:59:59.000Z

140

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

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.


141

Weak Parity Scott Aaronson  

E-Print Network [OSTI]

Weak Parity Scott Aaronson Andris Ambainis Kaspars Balodis Mohammad Bavarian§ Abstract We study elementary remarks about WEAK PARITY. (i) Of course it's trivial to guess PAR(X) on a 1/2 fraction of inputs

Aaronson, Scott

142

Using long-baseline interferometric gravitational waves detectors for high precision measures of the gravitational acceleration  

E-Print Network [OSTI]

A derivation of the optical axis lenght fluctations due by tilts of the mirrors of the Fabry-Perot cavity of long-baseline interferometers for the detection of gravitational waves in presence of the gravitational field of the earth is discussed. By comparing with the typical tilt-induced noises it is shown that this potential signal, which is considered a weak source of noise, is negligible for the first generation of gravitational waves interferometers, but, in principle, this effect could be used for high precision measures of the gravitational acceleration if advanced projects will achieve an high sensitivity. In that case the precision of the misure could be higher than the gravimeter realized by the Istituto di Metrologia ``Gustavo Colonnetti''.

Christian Corda

2007-01-25T23:59:59.000Z

143

astroph/9507030 Gravitational Radiation  

E-Print Network [OSTI]

astro­ph/9507030 10 Jul 95 Gravitational Radiation and Very Long Baseline Interferometry Ted Pyne of gravitational radiation on astrometric observations. We derive an equation for the time delay measured by two antennae observing the same source in an Einstein­de Sitter spacetime containing gravitational radiation

Fygenson, Deborah Kuchnir

144

Gravitational lens modelling in a citizen science context  

E-Print Network [OSTI]

We develop a method to enable collaborative modelling of gravitational lenses and lens candidates, that could be used by non-professional lens enthusiasts. It uses an existing free-form modelling program (glass), but enables the input to this code to be provided in a novel way, via a user-generated diagram that is essentially a sketch of an arrival-time surface. We report on an implementation of this method, SpaghettiLens, which has been tested in a modelling challenge using 29 simulated lenses drawn from a larger set created for the Space Warps citizen science strong lens search. We find that volunteers from this online community asserted the image parities and time ordering consistently in some lenses, but made errors in other lenses depending on the image morphology. While errors in image parity and time ordering lead to large errors in the mass distribution, the enclosed mass was found to be more robust: the model-derived Einstein radii found by the volunteers were consistent with those produced by one of...

Küng, Rafael; More, Anupreeta; Baeten, Elisabeth; Coles, Jonathan; Cornen, Claude; Macmillan, Christine; Marshall, Phil; More, Surhud; Odermatt, Jonas; Verma, Aprajita; Wilcox, Julianne K

2015-01-01T23:59:59.000Z

145

Detecting First Star Lyman-$?$ Spheres through Gravitational Telescopes  

E-Print Network [OSTI]

Lyman-$\\alpha$ spheres, i.e. regions around the first stars which are illuminated by Lyman-$\\alpha$ photons and show 21cm absorption feature against the CMB, are smoking guns at the dawn of the reionization epoch. Though overwhelming radio foreground makes their detections extremely difficult, we pointed out that, strong gravitational lensing can significantly improve their observational feasibility. Since Lyman-$\\alpha$ spheres have ~10" sizes, comparable to the caustic size of galaxy clusters, individual images of each strongly lensed Lyman-$\\alpha$ sphere often merge together and form single structures in the 21cm sky with irregular shapes. Using high-resolution N-body LCDM simulations, we found that the lensing probability to have magnification bigger than 10 is ~10^{-5}. This results in $\\ga 10^6$ strongly lensed Lyman-$\\alpha$ spheres across the sky, which should be the primary targets for first detections of Lyman-$\\alpha$ spheres. Although the required total radio array collecting area for their detection is large (~100 km^2), the design of long fixed cylindrical reflectors can significantly reduce the total cost of such array to the level of the square kilometer array (SKA) and makes the detection of these very first objects feasible.

Guoliang Li; Pengjie Zhang; Xuelei Chen

2007-09-12T23:59:59.000Z

146

Red Shift from Gravitational Back Reaction  

E-Print Network [OSTI]

Deviations from geodesic motion caused by gravitational radiation have been discussed in the last decades to describe the motion of particles or photons in strong fields around collapsed objects. On cosmological scale this effect, which in the first order is caused by the finite speed of gravitational interaction, is important also in the weak field limit. In this paper the energy loss by transfer to the gravitational potential is determined in a quasi-Newtonian approximation for the examples of a static Einstein universe and for an expanding universe with flat metric. In both cases the resulting red shift is a considerable fraction of the total red shift and requires an adjustment of the age and the matter composition in our models of the universe.

Ernst Fischer

2007-03-30T23:59:59.000Z

147

On calculation of microlensing light curve by gravitational lens caustic  

E-Print Network [OSTI]

For an analysis of microlensing observational data in case of binary gravitational lenses as well as for an interpretation of observations of high magnification events in multiple images of a lensed quasar it is necessary to calculate for a given source the microlensing light curve by a fold caustic. This problem comes to the numerical calculation of a singular integral. We formulated the sufficient condition of a convergence of the integral sum for this singular integral. The strictly approach to the problem of a comparison of model results with the unequally sampled observational data consists in calculation of the model light curve in equidistant points of the canonical dissection of the integration segment and a following interpolation of its values at the moments of observations.

M. B. Bogdanov

2001-02-02T23:59:59.000Z

148

Inverse Square Law of Gravitation in (2+1)-Dimensional Space-Time as a Consequence of Casimir Energy  

E-Print Network [OSTI]

The gravitational effect of vacuum polarization in space exterior to a particle in (2+1)-dimensional Einstein theory is investigated. In the weak field limit this gravitational field corresponds to an inverse square law of gravitational attraction, even though the gravitational mass of the quantum vacuum is negative. The paradox is resolved by considering a particle of finite extension and taking into account the vacuum polarization in its interior.

H. H. Soleng

1993-10-04T23:59:59.000Z

149

Quantum-mechanical description of Lense-Thirring effect for relativistic scalar particles  

E-Print Network [OSTI]

Exact expression for the Foldy-Wouthuysen Hamiltonian of scalar particles is used for a quantum-mechanical description of the relativistic Lense-Thirring effect. The exact evolution of the angular momentum operator in the Kerr field approximated by a spatially isotropic metric is found. The quantum-mechanical description of the full Lense-Thirring effect based on the Laplace-Runge-Lenz vector is given in the nonrelativistic and weak-field approximation. Relativistic quantum-mechanical equations for the velocity and acceleration operators are obtained. The equation for the acceleration defines the Coriolis-like and centrifugal-like accelerations and presents the quantum-mechanical description of the frame-dragging effect.

Alexander J. Silenko

2014-08-10T23:59:59.000Z

150

NEARBY PLANETARY SYSTEMS AS LENSES DURING PREDICTED CLOSE PASSAGES TO BACKGROUND STARS  

SciTech Connect (OSTI)

The Einstein rings and proper motions of nearby stars tend to be large. Thus, every year some foreground stars within a few hundred parsecs of Earth induce gravitational lensing events in background stars. In some of these cases, the events may exhibit evidence of planets orbiting the nearby star. In fact, planets can even be discovered during relatively distant passages. Here, we study the lensing signatures associated with planets orbiting nearby high-proper-motion stars. We find the following. (1) Wide-orbit planets can be detected for all distances of closest approach between the foreground and background stars, potentially producing independent events long before and/or after the closest approach. (2) Close-orbit planets can be detected for intermediate distances of closest approach, producing quasiperiodic signatures that may occur days or weeks before and after the stellar-lens event. (3) Planets in the so-called zone for resonant lensing can significantly increase the magnification when the distance of closest approach is small, making the stellar-lens event easier to detect, while simultaneously providing evidence for planets. Because approaches close enough to allow planets to be detected can be predicted, we can plan observing strategies to take advantage of the theoretical framework built in this paper, which describes the sequence of expected effects in terms of a sequence of detection regimes.

Di Stefano, Rosanne; Matthews, James [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Lepine, Sebastien [Department of Astrophysics, Division of Physical Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States)

2013-07-10T23:59:59.000Z

151

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.

152

Gravitation and electromagnetism  

E-Print Network [OSTI]

Maxwell's equations comprise both electromagnetic and gravitational fields. The transverse part of the vector potential belongs to magnetism, the longitudinal one is concerned with gravitation. The Coulomb gauge indicates that longitudinal components of the fields propagate instantaneously. The delta-function singularity of the field of the divergence of the vector potential, referred to as the dilatation center, represents an elementary agent of gravitation. Viewing a particle as a source or a scattering center of the point dilatation, the Newton's gravitation law can be reproduced.

V. P. Dmitriyev

2002-07-23T23:59:59.000Z

153

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

2009-06-15T23:59:59.000Z

154

Compensation for thermal effects in mirrors of Gravitational Wave Interferometers  

E-Print Network [OSTI]

In this paper we study several means of compensating for thermal lensing which, otherwise, should be a source of concern for future upgrades of interferometric detectors of gravitational waves. The methods we develop are based on the principle of heating the cold parts of the mirrors. We find that thermal compensation can help a lot but can not do miracles. It seems finally that the best strategy for future upgrades (``advanced configurations'') is maybe to use thermal compensation together with another substrate materials than Silica, for example Sapphire.

P. Hello

2001-04-18T23:59:59.000Z

155

Scalar and Vector Field Constraints, Deflection of Light and Lensing in Modified Gravity (MOG)  

E-Print Network [OSTI]

A conformal coupling of the metric in the Jordan frame to the energy-momentum tensor, screens the scalar field gravitational coupling strength $G$ in modified gravity (MOG). The scalar field acquires a mass which depends on the local matter density: the scalar field particle is massive for the Sun and earth, where the density is high compared to low density environments in cosmology and astrophysics. Together with the screening of the vector field $\\phi_\\mu$, this guarantees that solar system tests of gravity are satisfied. The conformal metric is coupled to the electromagnetic matter field and energy-momentum tensor, screening $G$ for the Sun and the deflection of light by the Sun and the Shapiro time delay in MOG are in agreement with general relativity. For galaxies and galactic clusters the enhanced gravitational coupling constant $G$ leads to agreement with gravitational lensing without dark matter. For compact binary pulsars the screening of $G$ removes the monopole and dipole gravitational radiation modes in agreement with the binary pulsar timing data.

J. W. Moffat

2014-10-06T23:59:59.000Z

156

Electromagnetic waves and Stokes parameters in the wake of a gravitational wave  

E-Print Network [OSTI]

A theoretical description of electromagnetic waves in the background of a (weak) gravitational wave is presented. Explicit expressions are obtained for the Stokes parameters during the passage of a plane-fronted gravitational wave described by the Ehlers-Kundt metric. In particular, it is shown that the axis of the polarization ellipse oscillates, its ellipticity remaining constant.

Shahen Hacyan

2012-06-15T23:59:59.000Z

157

Gravitational wave astronomy - astronomy of the 21st century  

E-Print Network [OSTI]

An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with interferometric gravitational wave observatories or detectors and several such detectors have been built or being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front - the IndIGO project -, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.

S. V. Dhurandhar

2011-04-15T23:59:59.000Z

158

Electromagnetism and Gravitation  

E-Print Network [OSTI]

The classical concept of "mass density" is not fundamental to the quantum theory of matter. Therefore, mass density cannot be the source of gravitation. Here, we treat electromagnetic energy, momentum, and stress as its source. The resulting theory predicts that the gravitational potential near any charged elementary particle is many orders of magnitude greater than the Newtonian value.

Kenneth Dalton

1997-03-10T23:59:59.000Z

159

Reconstructing the projected gravitational potential of Abell 1689 from X-ray measurements  

E-Print Network [OSTI]

Context. Galaxy clusters can be used as cosmological probes, but to this end, they need to be thoroughly understood. Combining all cluster observables in a consistent way will help us to understand their global properties and their internal structure. Aims. We provide proof of the concept that the projected gravitational potential of galaxy clusters can directly be reconstructed from X-ray observations. We also show that this joint analysis can be used to locally test the validity of the equilibrium assumptions in galaxy clusters. Methods. We used a newly developed reconstruction method, based on Richardson-Lucy deprojection, that allows reconstructing projected gravitational potentials of galaxy clusters directly from X-ray observations. We applied this algorithm to the well-studied cluster Abell 1689 and compared the gravitational potential reconstructed from X-ray observables to the potential obtained from gravitational lensing measurements. [...] Results. Assuming spherical symmetry and hydrostatic equili...

Tchernin, Celine; Meyer, Sven; Sarli, Eleonora; Eckert, Dominique; Bartelmann, Matthias

2015-01-01T23:59:59.000Z

160

Smooth sandwich gravitational waves  

E-Print Network [OSTI]

Gravitational waves which are smooth and contain two asymptotically flat regions are constructed from the homogeneous pp-waves vacuum solution. Motion of free test particles is calculated explicitly and the limit to an impulsive wave is also considered.

J. Podolsky

1998-07-16T23:59:59.000Z

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.


161

Gravitation and Duality Symmetry  

E-Print Network [OSTI]

By generalizing the Hodge dual operator to the case of soldered bundles, and working in the context of the teleparallel equivalent of general relativity, an analysis of the duality symmetry in gravitation is performed. Although the basic conclusion is that, at least in the general case, gravitation is not dual symmetric, there is a particular theory in which this symmetry shows up. It is a self dual (or anti-self dual) teleparallel gravity in which, due to the fact that it does not contribute to the interaction of fermions with gravitation, the purely tensor part of torsion is assumed to vanish. The ensuing fermionic gravitational interaction is found to be chiral. Since duality is intimately related to renormalizability, this theory may eventually be more amenable to renormalization than teleparallel gravity or general relativity.

V. C. de Andrade; A. L. Barbosa; J. G. Pereira

2005-05-16T23:59:59.000Z

162

Propagation of gravitational waves in a universe with slowly-changing equation of state  

E-Print Network [OSTI]

An exact solution for the expansion of a flat universe with dark energy evolving according to a simple model is explored. The equation for weak primordial gravitational waves propagating in this universe is solved and explored; gravitational waves in a flat cosmology possessing both a "big bang" singularity and a "big rip" singularity can be described with confluent Heun functions. We develop approximation methods for confluent Heun equations in regimes of interest to gravitational wave astronomers and predict the diminution in gravitational wave amplitude in a universe with both a Big Bang and a Big Rip.

Edmund Schluessel

2014-06-17T23:59:59.000Z

163

Interferometric Plasmonic Lensing with Nanohole Arrays  

SciTech Connect (OSTI)

Nonlinear photoemission electron microscopy (PEEM) of nanohole arrays in gold films maps propagating surface plasmons (PSPs) launched from lithographically patterned structures. Strong near field photoemission patterns are observed in the PEEM images, recorded following low angle of incidence irradiation of nanohole arrays with sub-15 fs laser pulses centered at 780 nm. The recorded photoemission patterns are attributed to constructive and destructive interferences between PSPs launched from the individual nanoholes which comprise the array. By exploiting the wave nature of PSPs, we demonstrate how varying the array geometry (hole diameter, pitch, and number of rows/columns) ultimately yields intense localized photoemission. Through a combination of PEEM and finite-difference time-domain simulations, we identify the optimal array geometry for efficient light coupling and interferometric plasmonic lensing. We show a preliminary application of inteferometric plasmonic lensing by enhancing the photoemission from the vertex of a gold triangle using nanohole array.

Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

2014-12-18T23:59:59.000Z

164

A genetic algorithm for the non-parametric inversion of strong lensing systems  

E-Print Network [OSTI]

We present a non-parametric technique to infer the projected-mass distribution of a gravitational lens system with multiple strong-lensed images. The technique involves a dynamic grid in the lens plane on which the mass distribution of the lens is approximated by a sum of basis functions, one per grid cell. We used the projected mass densities of Plummer spheres as basis functions. A genetic algorithm then determines the mass distribution of the lens by forcing images of a single source, projected back onto the source plane, to coincide as well as possible. Averaging several tens of solutions removes the random fluctuations that are introduced by the reproduction process of genomes in the genetic algorithm and highlights those features common to all solutions. Given the positions of the images and the redshifts of the sources and the lens, we show that the mass of a gravitational lens can be retrieved with an accuracy of a few percent and that, if the sources sufficiently cover the caustics, the mass distribution of the gravitational lens can also be reliably retrieved. A major advantage of the algorithm is that it makes full use of the information contained in the radial images, unlike methods that minimise the residuals of the lens equation, and is thus able to accurately reconstruct also the inner parts of the lens.

J. Liesenborgs; S. De Rijcke; H. Dejonghe

2006-01-06T23:59:59.000Z

165

Automation Enhancement of Multilayer Laue Lenses  

SciTech Connect (OSTI)

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

166

Non-statistical Weak Measurements  

E-Print Network [OSTI]

Non-statistical weak measurements yield weak values that are outside the range of eigenvalues and are not rare, suggesting that weak values are a property of every pre-and-post-selected ensemble. They also extend the applicability and valid regime of weak values.

Jeff Tollaksen; Yakir Aharonov

2006-07-28T23:59:59.000Z

167

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

168

Modeling a nonperturbative spinor vacuum interacting with a strong gravitational wave  

E-Print Network [OSTI]

We consider the propagation of strong gravitational waves interacting with a nonperturbative vacuum of spinor fields. To described the latter, we suggest an approximate model. The corresponding Einstein equation has the form of the Schr\\"odinger equation. Its gravitational-wave solution is analogous to the solution of the Schr\\"odinger equation for an electron moving in a periodic potential. The general solution for the periodic gravitational waves is found. The analog of the Kronig-Penney model for gravitational waves is considered. It is shown that the suggested gravitational-wave model permits the existence of weak electric charge and current densities concomitant with the gravitational wave. Based on this observation, a possible experimental verification of the model is suggested.

Vladimir Dzhunushaliev; Vladimir Folomeev

2015-03-15T23:59:59.000Z

169

Modeling a nonperturbative spinor vacuum interacting with a strong gravitational wave  

E-Print Network [OSTI]

We consider the propagation of strong gravitational waves interacting with a nonperturbative vacuum of spinor fields. To described the latter, we suggest an approximate model. The corresponding Einstein equation has the form of the Schr\\"odinger equation. Its gravitational-wave solution is analogous to the solution of the Schr\\"odinger equation for an electron moving in a periodic potential. The general solution for the periodic gravitational waves is found. The analog of the Kronig-Penney model for gravitational waves is considered. It is shown that the suggested gravitational-wave model permits the existence of weak electric charge and current densities concomitant with the gravitational wave. Based on this observation, a possible experimental verification of the model is suggested.

Dzhunushaliev, Vladimir

2015-01-01T23:59:59.000Z

170

E-Print Network 3.0 - accommodating intraocular lenses Sample...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

using a clinical Purkinje Summary: , Manzanera S, Norrby S, Artal P. Adaptive optics simulation of intraocular lenses with modified spherical... intraocular lenses....

171

A COSMIC MICROWAVE BACKGROUND LENSING MASS MAP AND ITS CORRELATION WITH THE COSMIC INFRARED BACKGROUND  

SciTech Connect (OSTI)

We use a temperature map of the cosmic microwave background (CMB) obtained using the South Pole Telescope at 150 GHz to construct a map of the gravitational convergence to z {approx} 1100, revealing the fluctuations in the projected mass density. This map shows individual features that are significant at the {approx}4{sigma} level, providing the first image of CMB lensing convergence. We cross-correlate this map with Herschel/SPIRE maps covering 90 deg{sup 2} at wavelengths of 500, 350, and 250 {mu}m. We show that these submillimeter (submm) wavelength maps are strongly correlated with the lensing convergence map, with detection significances in each of the three submm bands ranging from 6.7{sigma} to 8.8{sigma}. We fit the measurement of the cross power spectrum assuming a simple constant bias model and infer bias factors of b = 1.3-1.8, with a statistical uncertainty of 15%, depending on the assumed model for the redshift distribution of the dusty galaxies that are contributing to the Herschel/SPIRE maps.

Holder, G. P.; De Haan, T.; Dobbs, M. A.; Dudley, J. [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada); Viero, M. P.; Bock, J. [California Institute of Technology, Pasadena, CA 91125 (United States); Zahn, O. [Berkeley Center for Cosmological Physics, Department of Physics, University of California, and Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Aird, K. A. [University of Chicago, Chicago, IL 60637 (United States); Benson, B. A.; Bhattacharya, S.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, Kansas City, MO 64110 (United States); Cho, H-M. [NIST Quantum Devices Group, Boulder, CO 80305 (United States); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States); George, E. M. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Halverson, N. W. [Department of Astrophysical and Planetary Sciences and Department of Physics, University of Colorado, Boulder, CO 80309 (United States); and others

2013-07-01T23:59:59.000Z

172

Probing the dark energy with strong lensing by clusters of galaxies  

E-Print Network [OSTI]

Observations of clusters of galaxies that gravitationally lens faint background galaxies can probe the amount and the equation of state, $\\5$, of the dark energy (quintessence) in the universe. Provided that the mass profile and the mass normalization of the cluster are determined, it is possible to constrain the cosmological parameters that enter the lensing equations by means of the angular diameter distances, by locating (either by observations of giant arcs and magnification bias effect) the critical lines corresponding to known redshift source populations of galaxies. This method can help to distinguish between accelerating and decelerating models of the universe. Furthermore, since the position of critical lines is affected, especially in low-matter density universes, by the properties of quintessence, the observations of a suitable number of lensing clusters at intermediate redshifts can determine the equation of state. A very preliminary application of the method to the cluster CL 0024+1654 seems to support a flat accelerating universe dominated by dark energy.

M. Sereno

2002-09-11T23:59:59.000Z

173

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

2014-04-16T23:59:59.000Z

174

Supersymmetry and gravitational duality  

SciTech Connect (OSTI)

We study how the supersymmetry algebra copes with gravitational duality. As a playground, we consider a charged Taub-Newman-Unti-Tamburino(NUT) solution of D=4, N=2 supergravity. We find explicitly its Killing spinors, and the projection they obey provides evidence that the dual magnetic momenta necessarily have to appear in the supersymmetry algebra. The existence of such a modification is further supported using an approach based on the Nester form. In the process, we find new expressions for the dual magnetic momenta, including the NUT charge. The same expressions are then rederived using gravitational duality.

Argurio, Riccardo; Dehouck, Francois; Houart, Laurent [Physique Theorique et Mathematique and International Solvay Institutes, Universite Libre de Bruxelles, C.P. 231, 1050 Bruxelles (Belgium)

2009-06-15T23:59:59.000Z

175

Affine Defects and Gravitation  

E-Print Network [OSTI]

We argue that the structure general relativity (GR) as a theory of affine defects is deeper than the standard interpretation as a metric theory of gravitation. Einstein-Cartan theory (EC), with its inhomogenous affine symmetry, should be the standard-bearer for GR-like theories. A discrete affine interpretation of EC (and gauge theory) yields topological definitions of momentum and spin (and Yang Mills current), and their conservation laws become discrete topological identities. Considerations from quantum theory provide evidence that discrete affine defects are the physical foundation for gravitation.

R. J. Petti

2014-12-12T23:59:59.000Z

176

Luminous and Dark Matter Profiles from Galaxies to Clusters: Bridging the Gap with Group-scale Lenses  

E-Print Network [OSTI]

Observations of strong gravitational lensing, stellar kinematics, and mass tracers on larger scales enable accurate measures of the distribution of dark matter and baryons in massive early-type galaxies (ETGs). While such techniques have previously been applied to galaxy-scale and cluster-scale lenses, the paucity of intermediate-mass systems with high-quality data has precluded a uniform analysis of mass-dependent trends. With the aim of bridging this gap, we present new observations and analyses of 10 group-scale lenses at =0.36 characterized by Einstein radii 2.5"-5.1" and a mean halo mass of M_200 = 10^14.0 Msol. For these groups, we find a mean halo concentration c_200 = 5.0 +- 0.8 consistent with unmodified cold dark matter halos and recent simulations of galaxy formation. By combining our data with other lens samples in the literature, we analyze the mass structure of ETGs in halos spanning the mass range 10^13-10^15 Msol using homogeneous methods and data. We show that the slope of the total density p...

Newman, Andrew B; Treu, Tommaso

2015-01-01T23:59:59.000Z

177

Tevatron Electron Lenses: Design and Operation  

SciTech Connect (OSTI)

Fermilab's Tevatron is currently the world's highest energy accelerator in which tightly focused beams of 980 GeV protons and antiprotons collide at two dedicated interaction points (IPs). Both beams share the same beam pipe and magnet aperture and, in order to avoid multiple detrimental head-on collisions, the beams are placed on separated orbits everywhere except the main IPs by using high-voltage (HV) electrostatic separators. The electromagnetic beam-beam interaction at the main IPs together with the long-range interactions between separated beams adversely affect the collider performance, reducing the luminosity integral per store (period of continuous collisions) by 10-30%. Tuning the collider operation for optimal performance becomes more and more cumbersome as the beam intensities and luminosity increase. The long-range effects which (besides being nonlinear) vary from bunch to bunch are particularly hard to mitigate. A comprehensive review of the beam-beam effects in the Tevatron Collider Run II can be found in Ref. [1]. The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [1]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [2]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported in [3,4,5]. In this paper we present design features of the Tevatron electron lenses (TELs), discuss the generation of electron beams, describe different modes of operation and outline the technical parameters of various subsystems.

Shiltsev, Vladimir; /Fermilab; Bishofberger, Kip; /Los Alamos; Kamerdzhiev, Vsevolod; /Fermilab; Kozub, Sergei; /Serpukhov, IHEP; Kufer, Matthew; Kuznetsov, Gennady; Martinez, Alexander; Olson, Marvin; Pfeffer, Howard; Saewert, Greg; Scarpine, Vic; /Fermilab; Seryi, Andrei; /SLAC; Solyak, Nikolai; /Fermilab; Sytnik, Veniamin; /Serpukhov, IHEP; Tiunov, Mikhail; /Novosibirsk, IYF; Tkachenko, Leonid; /Serpukhov, IHEP; Wildman, David; Wolff, Daniel; Zhang, Xiao-Long; /Fermilab

2011-09-12T23:59:59.000Z

178

THE FAINTEST RADIO SOURCE YET: EXPANDED VERY LARGE ARRAY OBSERVATIONS OF THE GRAVITATIONAL LENS SDSS J1004+4112  

SciTech Connect (OSTI)

We present new radio observations of the large-separation gravitationally lensed quasar SDSS J1004+4112, taken in a total of 6 hr of observations with the Expanded Very Large Array. The maps reach a thermal noise level of approximately 4 {mu}Jy. We detect four of the five lensed images at the 15-35 {mu}Jy level, representing a source of intrinsic flux density, after allowing for lensing magnification, of about 1 {mu}Jy, intrinsically probably the faintest radio source yet detected. This reinforces the utility of gravitational lensing in potentially allowing us to study nJy-level sources before the advent of the Square Kilometre Array. In an optical observation taken three months after the radio observation, image C is the brightest image, whereas the radio map shows flux density ratios consistent with previous optical observations. Future observations separated by a time delay will give the intrinsic flux ratios of the images in this source.

Jackson, N. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Alan Turing Building, Oxford Road, Manchester M13 9PL (United Kingdom)

2011-09-20T23:59:59.000Z

179

Construction progress of the RHIC electron lenses  

SciTech Connect (OSTI)

In polarized proton operation the RHIC performance is limited by the head-on beam-beam effect. To overcome this limitation two electron lenses are under construction. We give an overview of the construction progress. Guns, collectors and the warm electron beam transport solenoids with their power supplies have been constructed. The superconducting solenoids that guide the electron beam during the interaction with the proton beam are near completion. A test stand has been set up to verify the performance of the gun, collector and some of the instrumentation. The infrastructure is being prepared for installation, and simulations continue to optimize the performance.

Fischer W.; Altinbas, Z.; Anerella, M.; Beebe, E.; et al

2012-05-20T23:59:59.000Z

180

Electron beam generation in Tevatron electron lenses  

SciTech Connect (OSTI)

New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices.

Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; /Fermilab; Tiunov, M.; /Novosibirsk, IYF

2006-08-01T23:59:59.000Z

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 Interaction | Jefferson Lab  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched FerromagnetismWaste and Materials Disposition3 WaterFebruary 18,the Geeks:Weak

182

Compound Refractive Lenses for Thermal Neutron Applications  

SciTech Connect (OSTI)

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

183

Analytic Expression of the Genus in Weakly Non-Gaussian Field Induced by Gravity  

E-Print Network [OSTI]

The gravitational evolution of the genus of the density field in large-scale structure is analytically studied in a weakly nonlinear regime using second-order perturbation theory. Weakly nonlinear evolution produces asymmetry in the symmetric genus curve for Gaussian initial density field. The effect of smoothing the density field in perturbation theory on the genus curve is also evaluated and gives the dependence of the asymmetry of the genus curve on spectra of initial fluctuations.

T. Matsubara

1994-05-16T23:59:59.000Z

184

CVS $Revision: 2.2 $Date: 2001/10/10 02:28:52 Accepted to AJ Shapes and Shears, Stars and Smears: Optimal Measurements for Weak  

E-Print Network [OSTI]

: Optimal Measurements for Weak Lensing G. M. Bernstein & M. Jarvis Dept. of Astronomy, University became available (Valdes, Tyson, & Jarvis 1983; Tyson et al. 1984). Furthermore, optical and atmospheric not occur until CCD images of suÃ?cient depth and #12;eld were available (Tyson, Valdes, & Wenk 1990

Bernstein, Gary

185

Gravitational red-shift and deflection of slow light  

E-Print Network [OSTI]

We explore the nature of the classical propagation of light through media with strong frequency-dependent dispersion in the presence of a gravitational field. In the weak field limit, gravity causes a redshift of the optical frequency, which the slow-light medium converts into a spatially-varying index of refraction. This results in the bending of a light ray in the medium. We further propose experimental techniques to amplify and detect the phenomenon using weak value measurements. Independent heuristic and rigorous derivations of this effect are given.

J. Dressel; S. G. Rajeev; J. C. Howell; A. N. Jordan

2008-10-27T23:59:59.000Z

186

clusters derived from gravitational lensing and x-ray data sometimes differ by up to a  

E-Print Network [OSTI]

mating swarms that their predators--principally birds--can consume no more than 15% of the peak numbers (2000). 8. G. G. Raffelt, Annu. Rev. Nucl. Part. Sci. 49, 163 (1999). 9. CERN Axion Solar Telescope

187

Gravitational wave astronomy and cosmology  

E-Print Network [OSTI]

The first direct observation of gravitational waves' action upon matter has recently been reported by the BICEP2 experiment. Advanced ground-based gravitational-wave detectors are being installed. They will soon be commissioned, and then begin searches for high-frequency gravitational waves at a sensitivity level that is widely expected to reach events involving compact objects like stellar mass black holes and neutron stars. Pulsar timing arrays continue to improve the bounds on gravitational waves at nanohertz frequencies, and may detect a signal on roughly the same timescale as ground-based detectors. The science case for space-based interferometers targeting millihertz sources is very strong. The decade of gravitational-wave discovery is poised to begin. In this writeup of a talk given at the 2013 TAUP conference, we will briefly review the physics of gravitational waves and gravitational-wave detectors, and then discuss the promise of these measurements for making cosmological measurements in the near future.

Scott A. Hughes

2014-05-02T23:59:59.000Z

188

ADDENDUM on the mass neutrino oscillation in a gravitational field  

E-Print Network [OSTI]

In the article {\\it Gen. Rel. Grav.} {\\bf 32}, 1633 (2000), by J. G. Pereira and C. M. Zhang, the special relativity energy-momentum tensor was used to discuss the neutrino phase-splitting in a weak gravitational field. However, it would be more appropriate to use the general relativity energy-momentum tensor. When we do that, as we are going to see, some results change, but the basic conclusion remains the same.

J. G. Pereira; C. M. Zhang

2002-05-08T23:59:59.000Z

189

Harmonic generation of gravitational wave induced Alfven waves  

E-Print Network [OSTI]

Here we consider the nonlinear evolution of Alfven waves that have been excited by gravitational waves from merging binary pulsars. We derive a wave equation for strongly nonlinear and dispersive Alfven waves. Due to the weak dispersion of the Alfven waves, significant wave steepening can occur, which in turn implies strong harmonic generation. We find that the harmonic generation is saturated due to dispersive effects, and use this to estimate the resulting spectrum. Finally we discuss the possibility of observing the above process.

Mats Forsberg; Gert Brodin

2007-11-26T23:59:59.000Z

190

X-ray Lenses Fabricated by LIGA Technology  

SciTech Connect (OSTI)

X-ray refractive optical lens systems have been successfully elaborated, designed, fabricated at the Institute for Microstructure Technology at the Forschungszentrum Karlsruhe (Germany) using LIGA technology in recent years. The lenses are structured in a SU-8 polymer. The capability of the LIGA technique to create an arbitrary profile of the focusing microstructures allow the fabrication of lenses with different curvature radius of parabolic geometry, minimized absorption and a large depth of focus. Also a set of planar lens systems on one substrate can be realized with 17 lenses providing identical focal distances for different X-ray energies from 2 to over 100 keV. Nickel lenses fabricated by electroforming using polymer templates can be applied for energies larger than 80 keV. The parabolic crossed lenses are used for 2D nano focusing of monochromatic beams. The quasi-parabolic crossed lenses with a submicron focus and a focus depth of the centimetre range can be used as an achromatic system. Mosaic truncated parabolic lenses with a focusing aperture up to 1 mm are made to increase the X-ray intensity in the focused spot.

Nazmov, Vladimir; Last, Arndt; Saile, Volker [Institut fuer Microstrukturtechnik, Forschungszentrum Karlsruhe GmbH, 76021 Karlsruhe (Germany); Karlsruhe University, 76131 Karlsruhe (Germany); Reznikova, Elena; Mohr, Jurgen [Institut fuer Microstrukturtechnik, Forschungszentrum Karlsruhe GmbH, 76021 Karlsruhe (Germany); Simon, Rolf [Institut fuer Synchrotronstrahlung, Forschungszentrum Karlsruhe GmbH, 76021 Karlsruhe (Germany); DiMichiel, Marco [European Synchrotron Radiation Facility, BP220, 38043, Grenoble (France)

2007-01-19T23:59:59.000Z

191

Spatially Resolved Millimeter Spectroscopy of the Gravitational Lens PKS 1830-211  

E-Print Network [OSTI]

This paper presents data from the BIMA interferometer showing spatially resolved absorption spectra of the gravitationally lensed quasar PKS 1830-211. High-resolution (1.2 km/s) spectra were taken in two spectral windows centered on the redshifted frequencies of the HCO+(2-1) and HCN(2-1) molecular transitions. There is no molecular absorption in the northeast image but the southwest image reveals optically thick absorbing gas at these transition frequencies. Further analyses conclude that the spectra are consistent with completely saturated absorption in the southwest image and the line profiles suggest that the absorbing medium is complex, perhaps containing multiple components and small scale structure. The absorption occurs along a pencil beam through the lensing galaxy which is thought to be a late type spiral oriented almost face on. However, the spectra show absorption spanning more than 60 km/s which is difficult to explain for this scenario.

Swift, J; Frye, B L

2001-01-01T23:59:59.000Z

192

Primordial Gravitational Waves Enhancement  

E-Print Network [OSTI]

We reconsider the enhancement of primordial gravitational waves that arises from a quantum gravitational model of inflation. A distinctive feature of this model is that the end of inflation witnesses a brief phase during which the Hubble parameter oscillates in sign, changing the usual Hubble friction to anti-friction. An earlier analysis of this model was based on numerically evolving the graviton mode functions after guessing their initial conditions near the end of inflation. The current study is based on an equation which directly evolves the normalized square of the magnitude. We are also able to make a very reliable estimate for the initial condition using a rapidly converging expansion for the sub-horizon regime. Results are obtained for the energy density per logarithmic wave number as a fraction of the critical density. These results exhibit how the enhanced signal depends upon the number of oscillatory periods; they also show the resonant effects associated with particular wave numbers.

Maria G. Romania; N. C. Tsamis; R. P. Woodard

2011-08-08T23:59:59.000Z

193

Post-Newtonian gravitational effects in quantum interferometry  

E-Print Network [OSTI]

We investigate general properties of optical interferometry in stationary spacetimes and apply the obtained results focusing on quantum-optical experiments in near-Earth environments. We provide a rigorous expression for the {gravitationally induced} phase difference and adapt the parametrized post-Newtonian formalism for calculations of polarization rotation. We investigate two optical versions of the Colella-Overhauser-Werner experiment and show that the phase difference is independent of the post-Newtonian parameter $\\gamma$, making it a possible candidate for an optical test of the Einstein equivalence principle. Polarization rotation provides an example of the quantum clock variable, and while related to the optical Lense-Thirring effects, shows a qualitatively different behaviour.

Aharon Brodutch; Alexei Gilchrist; Thomas Guff; Alexander R. H. Smith; Daniel R. Terno

2014-12-08T23:59:59.000Z

194

Gravitation and Electromagnetism  

E-Print Network [OSTI]

The realms of gravitation, belonging to Classical Physics, and Electromagnetism, belonging to the Theory of the Electron and Quantum Mechanics have remained apart as two separate pillars, inspite of a century of effort by Physicists to reconcile them. In this paper it is argued that if we extend ideas of Classical spacetime to include in addition to non integrability non commutavity also, then such a reconcilation is possible.

B. G. Sidharth

2001-06-16T23:59:59.000Z

195

Design and demonstration of broadband thin planar diffractive acoustic lenses  

SciTech Connect (OSTI)

We present here two diffractive acoustic lenses with subwavelength thickness, planar profile, and broad operation bandwidth. Tapered labyrinthine unit cells with their inherently broadband effective material properties are exploited in our design. Both the measured and the simulated results are showcased to demonstrate the lensing effect over more than 40% of the central frequency. The focusing of a propagating Gaussian modulated sinusoidal pulse is also demonstrated. This work paves the way for designing diffractive acoustic lenses and more generalized phase engineering diffractive elements with labyrinthine acoustic metamaterials.

Wang, Wenqi; Xie, Yangbo; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A., E-mail: cummer@ee.duke.edu [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

2014-09-08T23:59:59.000Z

196

The binary gravitational lens and its extreme cases  

E-Print Network [OSTI]

The transition of the binary gravitational lens from the equal mass case to small (planetary) mass ratios q is studied. It is shown how the limit of a (pure shear) Chang-Refsdal lens is approached, under what conditions the Chang-Refsdal approximation is valid, and how the 3 different topologies of the critical curves and caustics for a binary lens are mapped onto the 2 different topologies for a Chang-Refsdal lens with pure shear. It is shown that for wide binaries, the lensing in the vicinity of both lens objects can be described by a Taylor-expansion of the deflection term due to the other object, where the Chang-Refsdal approximation corresponds to a truncation of this series. For close binaries, only the vicinity of the secondary, less massive, object can be described in this way. However, for image distances much larger than the separation of the lens objects, any binary lens can be approximated by means of multipole expansion, where the first non-trivial term is the quadrupole term. It is shown that an ambiguity exists between wide and close binary lenses, where the shear at one of the objects due to the other object for the wide binary is equal to the absolute value of the eigenvalues of the quadrupole moment for the close binary. This analysis provides the basis for a classification of binary lens microlensing events, especially of planetary events, and an understanding of present ambiguities.

M. Dominik

1999-09-10T23:59:59.000Z

197

Thermodynamics and gravitational collapse  

E-Print Network [OSTI]

It is known now that a typical gravitational collapse in general relativity, evolving from regular initial data and under physically reasonable conditions would end in either a black hole or a naked singularity final state. An important question that needs to be answered in this connection is, whether the analogues of the laws of thermodynamics, as formulated for relativistic horizons are respected by the dynamical spacetimes for collapse that end in the formation of a naked singularity. We investigate here the thermodynamical behaviour of the dynamical horizons that form in spherically symmetric gravitational collapse and we show that the first and second laws of black hole thermodynamics, as extended to dynamical spacetimes in a suitable manner, are not violated whether the collapse ends in a black hole or a naked singularity. We then make a distinction between the naked singularities that result from gravitational collapse, and those that exist in solutions of Einstein equations in vacuum axially symmetric and stationary spacetimes, and discuss their connection with thermodynamics in view of the cosmic censorship conjecture and the validity of the third law of black hole mechanics.

Daniele Malafarina; Pankaj S. Joshi

2011-06-19T23:59:59.000Z

198

Adhesive Gravitational Clustering  

E-Print Network [OSTI]

The notion of `adhesion' has been advanced for the phenomenon of stabilization of large-scale structure emerging from gravitational instability of a cold medium. Recently, the physical origin of adhesion has been identified: a systematic derivation of the equations of motion for the density and the velocity fields leads naturally to the key equation of the `adhesion approximation' - however, under a set of strongly simplifying assumptions. In this work, we provide an evaluation of the current status of adhesive gravitational clustering and a clear explanation of the assumptions involved. Furthermore, we propose systematic generalizations with the aim to relax some of the simplifying assumptions. We start from the general Newtonian evolution equations for self-gravitating particles on an expanding Friedmann background and recover the popular `dust model' (pressureless fluid), which breaks down after the formation of density singularities; then we investigate, in a unified framework, two other models which, under the restrictions referred to above, lead to the `adhesion approximation'. We apply the Eulerian and Lagrangian perturbative expansions to these new models and, finally, we discuss some non-perturbative results that may serve as starting points for workable approximations of non-linear structure formation in the multi-stream regime. In particular, we propose a new approximation that includes, in limiting cases, the standard `adhesion model' and the Eulerian as well as Lagrangian first-order approximations.

Thomas Buchert; Alvaro Dominguez

2005-06-21T23:59:59.000Z

199

Projected Constraints on Lorentz-Violating Gravity with Gravitational Waves  

E-Print Network [OSTI]

Gravitational waves are excellent tools to probe the foundations of General Relativity in the strongly dynamical and non-linear regime. One such foundation is Lorentz symmetry, which can be broken in the gravitational sector by the existence of a preferred time direction, and thus, a preferred frame at each spacetime point. This leads to a modification in the orbital decay rate of binary systems, and also in the generation and chirping of their associated gravitational waves. We here study whether waves emitted in the late, quasi-circular inspiral of non-spinning, neutron star binaries can place competitive constraints on two proxies of gravitational Lorentz-violation: Einstein-\\AE{}ther theory and khronometric gravity. We model the waves in the small-coupling (or decoupling) limit and in the post-Newtonian approximation, by perturbatively solving the field equations in small deformations from General Relativity and in the small-velocity/weak-gravity approximation. We assume a gravitational wave consistent with General Relativity has been detected with second- and third-generation, ground-based detectors, and with the proposed space-based mission, DECIGO, with and without coincident electromagnetic counterparts. Without a counterpart, a detection consistent with General Relativity of neutron star binaries can only place competitive constraints on gravitational Lorentz violation when using future, third-generation or space-based instruments. On the other hand, a single counterpart is enough to place constraints that are 10 orders of magnitude more stringent than current binary pulsar bounds, even when using second-generation detectors. This is because Lorentz violation forces the group velocity of gravitational waves to be different from that of light, and this difference can be very accurately constrained with coincident observations.

Devin Hansen; Nicolas Yunes; Kent Yagi

2014-12-12T23:59:59.000Z

200

II - Conservation of Gravitational Energy Momentum and Poincare-Covariant Classical Theory of Gravitation  

E-Print Network [OSTI]

Viewing gravitational energy-momentum $p_G^\\mu$ as equal by observation, but different in essence from inertial energy-momentum $p_I^\\mu$ naturally leads to the gauge theory of volume-preserving diffeormorphisms of an inner Minkowski space ${\\bf M}^{\\sl 4}$. To extract its physical content the full gauge group is reduced to its Poincar\\'e subgroup. The respective Poincar\\'e gauge fields, field strengths and Poincar\\'e-covariant field equations are obtained and point-particle source currents are derived. The resulting set of non-linear field equations coupled to point matter is solved in first order resulting in Lienard-Wiechert-like potentials for the Poincar\\'e fields. After numerical identification of gravitational and inertial energy-momentum Newton's inverse square law for gravity in the static non-relativistic limit is recovered. The Weak Equivalence Principle in this approximation is proven to be valid and spacetime geometry in the presence of Poincar\\'e fields is shown to be curved. Finally, the gravitational radiation of an accelerated point particle is calulated.

C. Wiesendanger

2011-03-02T23:59:59.000Z

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.


201

On the Energy of Rotating Gravitational Waves  

E-Print Network [OSTI]

A class of solutions of the gravitational field equations describing vacuum spacetimes outside rotating cylindrical sources is presented. A subclass of these solutions corresponds to the exterior gravitational fields of rotating cylindrical systems that emit gravitational radiation. The properties of these rotating gravitational wave spacetimes are investigated. In particular, we discuss the energy density of these waves using the gravitational stress-energy tensor.

Bahram Mashhoon; James C. McClune; Enrique Chavez; Hernando Quevedo

1996-09-06T23:59:59.000Z

202

Searching for Novel Gravitational Effects  

ScienceCinema (OSTI)

Stubbs, Chair of the Physics Department at Harvard University, discusses experiments that search for novel gravitational effect and scientific observations about it.

Christopher Stubb

2010-09-01T23:59:59.000Z

203

Gravitational lens optical scalars in terms of energy-momentum distributions  

E-Print Network [OSTI]

This is a general work on gravitational lensing. We present new expressions for the optical scalars and the deflection angle in terms of the energy-momentum tensor components of matter distributions. Our work generalizes standard references in the literature where normally stringent assumptions are made on the sources. The new expressions are manifestly gauge invariant, since they are presented in terms of curvature components. We also present a method of approximation for solving the lens equations, that can be applied to any order.

Emanuel Gallo; Osvaldo M. Moreschi

2011-05-09T23:59:59.000Z

204

Constraining the Braneworld with Gravitational Wave Observations  

SciTech Connect (OSTI)

Some braneworld models may have observable consequences that, if detected, would validate a requisite element of string theory. In the infinite Randall-Sundrum model (RS2), the AdS radius of curvature, l, of the extra dimension supports a single bound state of the massless graviton on the brane, thereby reproducing Newtonian gravity in the weak-field limit. However, using the AdS/CFT correspondence, it has been suggested that one possible consequence of RS2 is an enormous increase in Hawking radiation emitted by black holes. We utilize this possibility to derive two novel methods for constraining l via gravitational wave measurements. We show that the EMRI event rate detected by LISA can constrain l at the {approx}1 {mu}m level for optimal cases, while the observation of a single galactic black hole binary with LISA results in an optimal constraint of l{<=}5 {mu}m.

McWilliams, Sean T. [Gravitational Astrophysics Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt Maryland 20771 (United States)

2010-04-09T23:59:59.000Z

205

Electromagnetic Induced Gravitational Perturbations  

E-Print Network [OSTI]

We study the physical consequences of two diffferent but closely related perturbation schemes applied to the Einstein-Maxwell equations. In one case the starting space-time is flat while in the other case it is Schwarzschild. In both cases the perturbation is due to a combined electric and magnetic dipole field. We can see, within the Einstein-Maxwell equations a variety of physical consequences. They range from induced gravitational energy-momentum loss, to a well defined spin angular momentum with its loss and a center-of-mass with its equations of motion.

T. M. Adamo; E. T. Newman

2008-07-23T23:59:59.000Z

206

Quantum Gravitational Optics  

E-Print Network [OSTI]

In quantum theory, the curved spacetime of Einstein's general theory of relativity acts as a dispersive optical medium for the propagation of light. Gravitational rainbows and birefringence replace the classical picture of light rays mapping out the null geodesics of curved spacetime. Even more remarkably, {\\it superluminal} propagation becomes a real possibility, raising the question of whether it is possible to send signals into the past. In this article, we review recent developments in the quantum theory of light propagation in general relativity and discuss whether superluminal light is compatible with causality.

Graham M Shore

2003-04-15T23:59:59.000Z

207

Weak Measurements via Quantum Erasure  

E-Print Network [OSTI]

Weak measurement is increasingly acknowledged as an important theoretical and experimental tool. Until now however, it was not known how to perform an efficient weak non-local measurement of a general operator. We propose a novel scheme for performing non-local weak measurement which is based on the principle of quantum erasure. This method is then demonstrated within a few gedanken experiments, and also applied to the case of measuring sequential weak values. Comparison with other protocols for extracting non-local weak values offers several advantages of the suggested algorithm. In addition to the practical merits, this scheme sheds new light on fundamental topics such as causality, non-locality, measurement and uncertainty.

Aharon Brodutch; Eliahu Cohen

2014-09-04T23:59:59.000Z

208

Momentum Imparted by Gravitational Waves  

E-Print Network [OSTI]

We calculate momentum imparted by colliding gravitational waves in a closed Friedmann Robertson-Walker background and also by gravitational waves with toroidal wavefronts using an operational procedure. The results obtained for toroidal wavefronts are well behaved and reduce to the spherical wavefronts for a special choice.

M. Sharif

2003-04-04T23:59:59.000Z

209

Weak Deeply Virtual Compton Scattering  

SciTech Connect (OSTI)

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

2007-03-01T23:59:59.000Z

210

Metrization in weakly sequential spaces  

E-Print Network [OSTI]

METRIZATION IN WEAXLY SEQUENTIAL SPACES A Thesis by DOMINIQUE MARGARET EMERSON Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1975 Ma)or Sub...]ect: Mathematics METRIZATION IN WEAKLY SEQUENTIAL SPACES A Thesis by DOMINIQUE MARGARET EMERSON Approved as to style and content by: (Chairman of Committee) c-0 (Head of Department) ember) (Member) May 1975 ABSTRACT Metrization in Weakly Sequential...

Emerson, Dominique Margaret

1975-01-01T23:59:59.000Z

211

USING THE BULLET CLUSTER AS A GRAVITATIONAL TELESCOPE TO STUDY z {approx}> 7 LYMAN BREAK GALAXIES  

SciTech Connect (OSTI)

We use imaging obtained with the Hubble Space Telescope Wide Field Camera 3 to search for z{sub 850} dropouts at z {approx} 7 and J{sub 110} dropouts at z {approx} 9 lensed by the Bullet Cluster. In total we find 10 z{sub 850} dropouts in our 8.27 arcmin{sup 2} field. Using magnification maps from a combined weak- and strong-lensing mass reconstruction of the Bullet Cluster and correcting for estimated completeness levels, we calculate the surface density and luminosity function of our z{sub 850} dropouts as a function of intrinsic (accounting for magnification) magnitude. We find results consistent with published blank field surveys, despite using much shallower data, and demonstrate the effectiveness of cluster surveys in the search for z {approx} 7 galaxies.

Hall, Nicholas; Bradac, Marusa [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, Anthony H. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Clowe, Douglas [Department of Physics and Astronomy, Ohio University, Clippinger Labs 251B, Athens, OH 45701 (United States); Jones, Christine [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Stiavelli, Massimo [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Zaritsky, Dennis [Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Cuby, Jean-Gabriel; Clement, Benjamin, E-mail: nrhall@ucdavis.edu [Laboratoire d'Astrophysique de Marseille, OAMP, Universite Aix-Marseille and CNRS, 38 rue Frederic Joliot Curie, F-13388 Marseille cedex 13 (France)

2012-02-01T23:59:59.000Z

212

A Lorentz-Poincaré type interpretation of the Weak Equivalence Principle  

E-Print Network [OSTI]

The validity of the Weak Equivalence Principle relative to a local inertial frame is detailed in a scalar-vector gravitation model with Lorentz-Poincar\\'e type interpretation. Given the previously established first Post-Newtonian concordance of dynamics with General Relativity, the principle is to this order compatible with GRT. The gravitationally modified Lorentz transformations, on which the observations in physical coordinates depend, are shown to provide a physical interpretation of \\emph{parallel transport}. A development of ``geodesic'' deviation in terms of the present model is given as well.

Jan; Broekaert

2007-03-22T23:59:59.000Z

213

Photon rockets and gravitational radiation  

E-Print Network [OSTI]

The absence of gravitational radiation in Kinnersley's ``photon rocket'' solution of Einstein's equations is clarified by studying the mathematically well-defined problem of point-like photon rockets in Minkowski space (i.e. massive particles emitting null fluid anisotro\\-pically and accelerating because of the recoil). We explicitly compute the (uniquely defined) {\\it linearized} retarded gravitational waves emitted by such objects, which are the coherent superposition of the gravitational waves generated by the motion of the massive point-like rocket and of those generated by the energy-momentum distribution of the photon fluid. In the special case (corresponding to Kinnersley's solution) where the anisotropy of the photon emission is purely dipolar we find that the gravitational wave amplitude generated by the energy-momentum of the photons exactly cancels the usual $1/r$ gravitational wave amplitude generated by the accelerated motion of the rocket. More general photon anisotropies would, however, generate genuine gravitational radiation at infinity. Our explicit calculations show the compatibility between the non-radiative character of Kinnersley's solution and the currently used gravitational wave generation formalisms based on post-Minkowskian perturbation theory.

T. Damour

1994-12-21T23:59:59.000Z

214

Degradation of Iris Recognition Performance Due to Non-Cosmetic Prescription Contact Lenses  

E-Print Network [OSTI]

stated as: "Subjects can generally be recognized through eyeglasses or contact lenses. Colored contact with the recognition technology" [5] and "Successful identification can be made through eyeglasses and contact lenses

Bowyer, Kevin W.

215

Breakdown of the equivalence between gravitational mass and energy for a composite quantum body  

E-Print Network [OSTI]

The simplest quantum composite body, a hydrogen atom, is considered in the presence of a weak external gravitational field. We define an operator for the passive gravitational mass of the atom in the post-Newtonian approximation of the general relativity and show that it does not commute with its energy operator. Nevertheless, the equivalence between the expectation values of the mass and energy is shown to survive at a macroscopic level for stationary quantum states. Breakdown of the equivalence between passive gravitational mass and energy at a microscopic level for stationary quantum states can be experimentally detected by studying unusual electromagnetic radiation, emitted by the atoms, supported by and moving in the Earth's gravitational field with constant velocity, using spacecraft or satellite

Andrei G. Lebed

2014-04-14T23:59:59.000Z

216

Dissipation of Modified Entropic Gravitational Energy Through Gravitational Waves  

E-Print Network [OSTI]

The phenomenological nature of a new gravitational type interaction between two different bodies derived from Verlinde's entropic approach to gravitation in combination with Sorkin's definition of Universe's quantum information content, is investigated. Assuming that the energy stored in this entropic gravitational field is dissipated under the form of gravitational waves and that the Heisenberg principle holds for this system, one calculates a possible value for an absolute minimum time scale in nature $\\tau=15/16 \\frac{\\Lambda^{1/2}\\hbar G}{c^4}\\sim9.27\\times10^{-105}$ seconds, which is much smaller than the Planck time $t_{P}=(\\hbar G/c^5)^{1/2}\\sim 5.38\\times10^{-44}$ seconds. This appears together with an absolute possible maximum value for Newtonian gravitational forces generated by matter $F_g=32/30\\frac{c^7}{\\Lambda \\hbar G^2}\\sim 3.84\\times 10^{165}$ Newtons, which is much higher than the gravitational field between two Planck masses separated by the Planck length $F_{gP}=c^4/G\\sim1.21\\times10^{44}$ Newtons.

Clovis Jacinto de Matos

2011-11-04T23:59:59.000Z

217

Week 13: Chapter 13 Universal Gravitation  

E-Print Network [OSTI]

1 Week 13: Chapter 13 Universal Gravitation Newton's Law of Universal Gravitation Every particle placed near the small ones The angle of rotation was measured Law of Gravitation, cont's Third Law action-reaction pair Gravitation is a field force that always exists between two particles

218

Gravitational waves: a foundational review  

E-Print Network [OSTI]

The standard linear approach to the gravitational waves theory is critically reviewed. Contrary to the prevalent understanding, it is pointed out that this theory contains many conceptual and technical obscure issues that require further analysis.

J. G. Pereira

2013-07-25T23:59:59.000Z

219

Dark Energy, Gravitation and Electromagnetism  

E-Print Network [OSTI]

In the context of the fact that the existence of dark energy causing the accelerated expansion of the universe has been confirmed by the WMAP and the Sloan Digital Sky Survey, we re-examine gravitation itself, starting with the formulation of Sakharov and show that it is possible to obtain gravitation in terms of the electromagnetic charge of elementary particles, once the ZPF and its effects at the Compton scale are taken into account.

B. G. Sidharth

2004-01-08T23:59:59.000Z

220

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

2002-11-11T23:59:59.000Z

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.


221

MAGNETOHYDRODYNAMIC SIMULATION OF A DISK SUBJECTED TO LENSE-THIRRING PRECESSION  

SciTech Connect (OSTI)

When matter orbits around a central mass obliquely with respect to the mass's spin axis, the Lense-Thirring effect causes it to precess at a rate declining sharply with radius. Ever since the work of Bardeen and Petterson, it has been expected that when a fluid fills an orbiting disk, the orbital angular momentum at small radii should then align with the mass's spin. Nearly all previous work has studied this alignment under the assumption that a phenomenological 'viscosity' isotropically degrades fluid shears in accretion disks, even though it is now understood that internal stress in flat disks is due to anisotropic MHD turbulence. In this paper we report a pair of matched simulations, one in MHD and one in pure (non-viscous) HD in order to clarify the specific mechanisms of alignment. As in the previous work, we find that disk warps induce radial flows that mix angular momentum of different orientation; however, we also show that the speeds of these flows are generically transonic and are only very weakly influenced by internal stresses other than pressure. In particular, MHD turbulence does not act in a manner consistent with an isotropic viscosity. When MHD effects are present, the disk aligns, first at small radii and then at large; alignment is only partial in the HD case. We identify the specific angular momentum transport mechanisms causing alignment and show how MHD effects permit them to operate more efficiently. Last, we relate the speed at which an alignment front propagates outward (in the MHD case) to the rate at which Lense-Thirring torques deliver angular momentum at smaller radii.

Sorathia, Kareem A.; Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Hawley, John F. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)

2013-11-01T23:59:59.000Z

222

CLUSTER LENSING PROFILES DERIVED FROM A REDSHIFT ENHANCEMENT OF MAGNIFIED BOSS-SURVEY GALAXIES  

SciTech Connect (OSTI)

We report the first detection of a redshift-depth enhancement of background galaxies magnified by foreground clusters. Using 300,000 BOSS survey galaxies with accurate spectroscopic redshifts, we measure their mean redshift depth behind four large samples of optically selected clusters from the Sloan Digital Sky Survey (SDSS) surveys, totaling 5000-15,000 clusters. A clear trend of increasing mean redshift toward the cluster centers is found, averaged over each of the four cluster samples. In addition, we find similar but noisier behavior for an independent X-ray sample of 158 clusters lying in the foreground of the current BOSS sky area. By adopting the mass-richness relationships appropriate for each survey, we compare our results with theoretical predictions for each of the four SDSS cluster catalogs. The radial form of this redshift enhancement is well fitted by a richness-to-mass weighted composite Navarro-Frenk-White profile with an effective mass ranging between M{sub 200} {approx} 1.4-1.8 Multiplication-Sign 10{sup 14} M{sub Sun} for the optically detected cluster samples, and M{sub 200} {approx} 5.0 Multiplication-Sign 10{sup 14} M{sub Sun} for the X-ray sample. This lensing detection helps to establish the credibility of these SDSS cluster surveys, and provides a normalization for their respective mass-richness relations. In the context of the upcoming bigBOSS, Subaru Prime Focus Spectrograph, and EUCLID-NISP spectroscopic surveys, this method represents an independent means of deriving the masses of cluster samples for examining the cosmological evolution, and provides a relatively clean consistency check of weak-lensing measurements, free from the systematic limitations of shear calibration.

Coupon, Jean; Umetsu, Keiichi [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Broadhurst, Tom, E-mail: coupon@asiaa.sinica.edu.tw [Department of Theoretical Physics, University of Basque Country UPV/EHU, P.O. Box 644, E-48080 Bilbao (Spain)

2013-07-20T23:59:59.000Z

223

Weak-Chaos Ratchet Accelerator  

E-Print Network [OSTI]

Classical Hamiltonian systems with a mixed phase space and some asymmetry may exhibit chaotic ratchet effects. The most significant such effect is a directed momentum current or acceleration. In known model systems, this effect may arise only for sufficiently strong chaos. In this paper, a Hamiltonian ratchet accelerator is introduced, featuring a momentum current for arbitrarily weak chaos. The system is a realistic, generalized kicked rotor and is exactly solvable to some extent, leading to analytical expressions for the momentum current. While this current arises also for relatively strong chaos, the maximal current is shown to occur, at least in one case, precisely in a limit of arbitrarily weak chaos.

Itzhack Dana; Vladislav B. Roitberg

2012-05-28T23:59:59.000Z

224

Cosmology and the weak interaction  

SciTech Connect (OSTI)

The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

Schramm, D.N. (Fermi National Accelerator Lab., Batavia, IL (USA)):(Chicago Univ., IL (USA))

1989-12-01T23:59:59.000Z

225

Satellite Parallaxes of Lensing Events Towards the Galactic Bulge  

E-Print Network [OSTI]

In order to understand the nature of the lenses that generate microlensing events, one would like to measure their mass, distance, and velocity. Unfortunately, current microlensing experiments measure only one parameter of the events, the characteristic timescale, which is a combination of the underlying physical parameters. Other methods are required to extract additional information. Parallax measurements using a satellite in an Earth-like orbit yield the projected velocity of the lens: ${\\bf{\\tilde v}} ={\\bf{v}}/(1-z)$, where ${\\bf{v}}$ is the transverse velocity (speed and direction) of the lens relative to the Earth-source line of sight, and $z$ is the ratio of the distances to the lens and the source. A measurement of ${\\bf{\\tilde v}}$ could distinguish between lenses belonging to the bulge and disk populations. We show that for photometric precisions of 1% to 2%, it is possible to measure the projected speed, $\\tilde v$, to an accuracy of $\\leq 10%$ for over 70% of disk lenses and over 60% of bulge lenses. For measuring the projected velocity ${\\bf{\\tilde v}}$, the percentages are 40% and {30%}, respectively. We find lines of sight $> 2^{\\circ}$ away from the ecliptic are preferable, and an Earth-satellite separation in the range $0.7 {\\rm{AU}} - 1.9{\\rm{AU}}$ is optimal. The requirements of the satellite for measuring the projected velocities of events towards the bulge are similar to those for measurements toward the LMC.

B. Scott Gaudi; Andrew Gould

1996-08-20T23:59:59.000Z

226

THE SLOAN BRIGHT ARCS SURVEY: DISCOVERY OF SEVEN NEW STRONGLY LENSED GALAXIES FROM z = 0.66-2.94  

SciTech Connect (OSTI)

We report the discovery of seven new, very bright gravitational lens systems from our ongoing gravitational lens search, the Sloan Bright Arcs Survey (SBAS). Two of the systems are confirmed to have high source redshifts z = 2.19 and z = 2.94. Three other systems lie at intermediate redshift with z = 1.33, 1.82, 1.93 and two systems are at low redshift z = 0.66, 0.86. The lensed source galaxies in all of these systems are bright, with i-band magnitudes ranging from 19.73 to 22.06. We present the spectrum of each of the source galaxies in these systems along with estimates of the Einstein radius for each system. The foreground lens in most systems is identified by a red sequence based cluster finder as a galaxy group; one system is identified as a moderately rich cluster. In total, SBAS has now discovered 19 strong lens systems in the SDSS imaging data, 8 of which are among the highest surface brightness z {approx_equal} 2-3 galaxies known.

Kubo, Jeffrey M.; Allam, Sahar S.; Drabek, Emily; Lin, Huan; Tucker, Douglas; Buckley-Geer, Elizabeth J.; Diehl, H. Thomas; Soares-Santos, Marcelle; Hao Jiangang; Kubik, Donna; Annis, James; Frieman, Joshua A. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Wiesner, Matthew [Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States); West, Anderson [The Illinois Math and Science Academy, Aurora, IL 60506 (United States)

2010-12-01T23:59:59.000Z

227

THE QUASAR-GALAXY CROSS SDSS J1320+1644: A PROBABLE LARGE-SEPARATION LENSED QUASAR  

SciTech Connect (OSTI)

We report the discovery of a pair of quasars at z = 1.487, with a separation of 8.''585 {+-} 0.''002. Subaru Telescope infrared imaging reveals the presence of an elliptical and a disk-like galaxy located almost symmetrically between the quasars, in a cross-like configuration. Based on absorption lines in the quasar spectra and the colors of the galaxies, we estimate that both galaxies are located at redshift z = 0.899. This, as well as the similarity of the quasar spectra, suggests that the system is a single quasar multiply imaged by a galaxy group or cluster acting as a gravitational lens, although the possibility of a binary quasar cannot be fully excluded. We show that the gravitational lensing hypothesis implies that these galaxies are not isolated, but must be embedded in a dark matter halo of virial mass {approx}4 Multiplication-Sign 10{sup 14} h {sup -1}{sub 70} M{sub Sun} assuming a Navarro-Frenk-White model with a concentration parameter of c{sub vir} = 6, or a singular isothermal sphere profile with a velocity dispersion of {approx}670 km s{sup -1}. We place constraints on the location of the dark matter halo, as well as the velocity dispersions of the galaxies. In addition, we discuss the influence of differential reddening, microlensing, and intrinsic variability on the quasar spectra and broadband photometry.

Rusu, Cristian E.; Iye, Masanori [Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan); Oguri, Masamune [Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8568 (Japan); Inada, Naohisa [Department of Physics, Nara National College of Technology, Yamatokohriyama, Nara 639-1080 (Japan); Kayo, Issha [Department of Physics, Toho University, Funabashi, Chiba 274-8510 (Japan); Shin, Min-Su [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Sluse, Dominique [Argelander-Institut fuer Astronomie, Auf dem Huegel 71, D-53121 Bonn (Germany); Strauss, Michael A. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)

2013-03-10T23:59:59.000Z

228

Weak values and weak coupling maximizing the output of weak measurements  

SciTech Connect (OSTI)

In a weak measurement, the average output ?o? of a probe that measures an observable A{sup -hat} of a quantum system undergoing both a preparation in a state ?{sub i} and a postselection in a state E{sub f} is, to a good approximation, a function of the weak value A{sub w}=Tr[E{sub f}A{sup -hat} ?{sub i}]/Tr[E{sub f}?{sub i}], a complex number. For a fixed coupling ?, when the overlap Tr[E{sub f}?{sub i}] is very small, A{sub w} diverges, but ?o? stays finite, often tending to zero for symmetry reasons. This paper answers the questions: what is the weak value that maximizes the output for a fixed coupling? What is the coupling that maximizes the output for a fixed weak value? We derive equations for the optimal values of A{sub w} and ?, and provide the solutions. The results are independent of the dimensionality of the system, and they apply to a probe having a Hilbert space of arbitrary dimension. Using the Schrödinger–Robertson uncertainty relation, we demonstrate that, in an important case, the amplification ?o? cannot exceed the initial uncertainty ?{sub o} in the observable o{sup -hat}, we provide an upper limit for the more general case, and a strategy to obtain ?o???{sub o}. - Highlights: •We have provided a general framework to find the extremal values of a weak measurement. •We have derived the location of the extremal values in terms of preparation and postselection. •We have devised a maximization strategy going beyond the limit of the Schrödinger–Robertson relation.

Di Lorenzo, Antonio, E-mail: dilorenzo.antonio@gmail.com

2014-06-15T23:59:59.000Z

229

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

2003-05-19T23:59:59.000Z

230

Optical Approach to Gravitational Redshift  

E-Print Network [OSTI]

An optical approach begins by interpreting the gravitational redshift resulting to a change in the relative velocity of light due to the medium of propagation in the gravitational field. The discussion continues by pointing out an agreement in structure between the equation for rays in geometrical optics and the geodesic equation of general relativity. From their comparison we learn that the path of rays should be given by the relation $ds^2=n^2(r)dr^2+r^2d\\theta^2$, not by $ds^2=dr^2+r^2d\\theta^2$, in a medium with spherical symmetry of refractive index $n(r)$. The development of an optical analogy suggests introducing $n^2(r)$ in place of $g_{rr}$ as an optical version of the Schwarzschild metric. In form and content, $n^2(r)$ is different from $g_{rr}$. The optical point of view replaces the general-relativity explanations in terms of time and gravitation.

Y. G. Yi

2012-04-12T23:59:59.000Z

231

THE OPTIMAL GRAVITATIONAL LENS TELESCOPE  

SciTech Connect (OSTI)

Given an observed gravitational lens mirage produced by a foreground deflector (cf. galaxy, quasar, cluster, ...), it is possible via numerical lens inversion to retrieve the real source image, taking full advantage of the magnifying power of the cosmic lens. This has been achieved in the past for several remarkable gravitational lens systems. Instead, we propose here to invert an observed multiply imaged source directly at the telescope using an ad hoc optical instrument which is described in the present paper. Compared to the previous method, this should allow one to detect fainter source features as well as to use such an optimal gravitational lens telescope to explore even fainter objects located behind and near the lens. Laboratory and numerical experiments illustrate this new approach.

Surdej, J.; Hanot, C.; Sadibekova, T. [Department of Astrophysics, Geophysics and Oceanography (AGO), AEOS Group, Liege University, Allee du 6 Aout 17, 4000 Liege (Belgium); Delacroix, C.; Habraken, S. [Department of Physics (DEPHY), Hololab Group, Liege University, Allee du 6 Aout 17, 4000 Liege (Belgium); Coleman, P. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Dominik, M. [SUPA, University of St Andrews, School of Physics and Astronomy, North Haugh, St Andrews, KY16 9SS (United Kingdom); Le Coroller, H. [Observatoire de Haute Provence, F-04870 Saint Michel l'Observatoire (France); Mawet, D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Quintana, H. [Departmento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, CL 22 Santiago (Chile); Sluse, D., E-mail: surdej@astro.ulg.ac.b [Astronomisches Rechen-Institut am Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstrasse 12-14, 69120 Heidelberg (Germany)

2010-05-15T23:59:59.000Z

232

Global Superdiffusion of Weak Chaos  

E-Print Network [OSTI]

A class of kicked rotors is introduced, exhibiting accelerator-mode islands (AIs) and {\\em global} superdiffusion for {\\em arbitrarily weak} chaos. The corresponding standard maps are shown to be exactly related to generalized web maps taken modulo an ``oblique cylinder''. Then, in a case that the web-map orbit structure is periodic in the phase plane, the AIs are essentially {\\em normal} web islands folded back into the cylinder. As a consequence, chaotic orbits sticking around the AI boundary are accelerated {\\em only} when they traverse tiny {\\em ``acceleration spots''}. This leads to chaotic flights having a quasiregular {\\em steplike} structure. The global weak-chaos superdiffusion is thus basically different in nature from the strong-chaos one in the usual standard and web maps.

Itzhack Dana

2003-10-20T23:59:59.000Z

233

Weak Interactions in Atoms Nuclear Anapole Moment Weak Coupling Constants Nuclear Anapole Moment  

E-Print Network [OSTI]

Weak Interactions in Atoms Nuclear Anapole Moment Weak Coupling Constants Nuclear Anapole Moment;Weak Interactions in Atoms Nuclear Anapole Moment Weak Coupling Constants Plan of the talk Weak Interactions in Atoms Charged and Neutral Currents. Effective P-odd Hamiltonian Nuclear Anapole Moment

Pines, Alexander

234

Gravitational wave background from Standard Model physics: Qualitative features  

E-Print Network [OSTI]

Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at T > 160 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future ge...

Ghiglieri, J

2015-01-01T23:59:59.000Z

235

Einstein's Energy-Free Gravitational Field  

E-Print Network [OSTI]

We show that Einstein's gravitational field has zero energy, momentum, and stress. This conclusion follows directly from the gravitational field equations, in conjunction with the differential law of energy-momentum conservation $ T^{\\mu\

Kenneth Dalton

1998-03-13T23:59:59.000Z

236

Gravitational waves from merging compact binaries  

E-Print Network [OSTI]

Largely motivated by the development of highly sensitive gravitational-wave detectors, our understanding of merging compact binaries and the gravitational waves they generate has improved dramatically in recent years. ...

Hughes, Scott A.

237

Lorentz Symmetry, the SME, and Gravitational Experiments  

E-Print Network [OSTI]

This proceedings contribution summarizes the implications of recent SME-based investigations of Lorentz violation for gravitational experiments.

Jay D. Tasson

2012-12-10T23:59:59.000Z

238

Lorentz Symmetry, the SME, and Gravitational Experiments  

E-Print Network [OSTI]

This proceedings contribution summarizes the implications of recent SME-based investigations of Lorentz violation for gravitational experiments.

Tasson, Jay D

2012-01-01T23:59:59.000Z

239

Gravitation and Special Relativity D. H. Sattinger  

E-Print Network [OSTI]

of Maxwell's equations for gravitation, based on a mathematical proof of Faraday's Law, is presentedGravitation and Special Relativity D. H. Sattinger Department of Mathematics University of Arizona of the perturbation theory of Ein- stein's equations, puts the gravitational and electromagnetic fields on an equal

Zakharov, Vladimir

240

Gravitational Radiation in Noncommutative Gravity  

E-Print Network [OSTI]

The gravitational radiation power of a binary system in a noncommutative space is derived and it's rate of the period decrease is calculated to first order in noncommutativity parameter. By comparing the theoretical results with the observational data of the binary pulsar PSR 1913+16, we find a bound on the noncommutativity parameter.

A. Jahan; N. Sadeghnezhad

2014-11-24T23:59:59.000Z

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

Microscopic Lensing by a Dense, Cold Atomic Sample  

E-Print Network [OSTI]

We demonstrate that a cold, dense sample of 87Rb atoms can exhibit a micron-scale lensing effect, much like that associated with a macroscopically-sized lens. The experiment is carried out in the fashion of traditional z-scan measurements but in much weaker fields and where close attention is paid to the detuning dependence of the transmitted light. The results are interpreted using numerical simulations and by modeling the sample as a thin lens with a spherical focal length.

Stetson Roof; Kasie Kemp; Mark Havey; I. M. Sokolov; D. V. Kupriyanov

2014-12-01T23:59:59.000Z

242

The 8 O'Clock Arc: A Serendipitous Discovery of a Strongly Lensed Lyman Break Galaxy in the SDSS DR4 Imaging Data  

SciTech Connect (OSTI)

We report on the serendipitous discovery of the brightest Lyman Break Galaxy (LBG) currently known, a galaxy at z = 2.73 that is being strongly lensed by the z = 0.38 Luminous Red Galaxy (LRG) SDSS J002240.91+143110.4. The arc of this gravitational lens system, which we have dubbed the ''8 o'clock arc'' due to its time of discovery, was initially identified in the imaging data of the Sloan Digital Sky Survey Data Release 4 (SDSS DR4); followup observations on the Astrophysical Research Consortium (ARC) 3.5m telescope at Apache Point Observatory confirmed the lensing nature of this system and led to the identification of the arc's spectrum as that of an LBG. The arc has a spectrum and a redshift remarkably similar to those of the previous record-holder for brightest LBG (MS 1512-cB58, a.k.a ''cB58''), but, with an estimated total magnitude of (g,r,i) = (20.0,19.2,19.0) and surface brightness of ({mu}{sub g}, {mu}{sub r}, {mu}{sub i}) = (23.3, 22.5, 22.3) mag arcsec{sup -2}, the 8 o'clock arc is thrice as bright. The 8 o'clock arc, which consists of three lensed images of the LBG, is 162{sup o}(9.6'') long and has a length-to-width ratio of 6:1. A fourth image of the LBG--a counter-image--can also be identified in the ARC 3.5m g-band images. A simple lens model for the system assuming a singular isothermal ellipsoid potential yields an Einstein radius of {theta}{sub Ein} = 2.91'' {+-} 0.14'', a total mass for the lensing LRG (within the 10.6 {+-} 0.5 h{sup -1} kpc enclosed by the lensed images) of 1.04 x 10{sup 12} h{sup -1} M{sub {circle_dot}}, and a magnification factor for the LBG of 12.3{sub -3.6}{sup +15}. The LBG itself is intrinsically quite luminous ({approx} 6 x L{sub *}) and shows indications of massive recent star formation, perhaps as high as 160 h{sup -1} M{sub {circle_dot}} yr{sup -1}.

Allam, Sahar S.; /Fermilab /Wyoming U.; Tucker, Douglas L.; Lin, Huan; Diehl, H.Thomas; Annis, James; Buckley-Geer, Elizabeth J.; /Fermilab; Frieman, Joshua A.; /Fermilab

2006-11-01T23:59:59.000Z

243

Electrostatic self-force in a static weak gravitational field with cylindrical symmetry  

E-Print Network [OSTI]

We determine the electrostatic self-force at rest in an arbitrary static metric with cylindrical symmetry in the linear approximation in the Newtonian constant. In linearised Einstein theory, we express it in terms of the components of the energy-momentum tensor.

B. Boisseau; C. Charmousis; B. Linet

1996-03-04T23:59:59.000Z

244

Co-planning among science and special education teachers: How do different conceptual lenses help to make sense of the process?  

E-Print Network [OSTI]

how do different conceptual lenses help to make sense of thehow do different conceptual lenses help to make sense of theconceptual lenses to help make sense of this process: (1)

Swanson, Lauren H; Bianchini, Julie A

2014-01-01T23:59:59.000Z

245

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

SciTech Connect (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

246

Gravitational wave radiometry: Mapping a stochastic gravitational wave background  

SciTech Connect (OSTI)

The problem of the detection and mapping of a stochastic gravitational wave background (SGWB), either cosmological or astrophysical, bears a strong semblance to the analysis of the cosmic microwave background (CMB) anisotropy and polarization, which too is a stochastic field, statistically described in terms of its correlation properties. An astrophysical gravitational wave background (AGWB) will likely arise from an incoherent superposition of unmodelled and/or unresolved sources and cosmological gravitational wave backgrounds (CGWB) are also predicted in certain scenarios. The basic statistic we use is the cross correlation between the data from a pair of detectors. In order to ''point'' the pair of detectors at different locations one must suitably delay the signal by the amount it takes for the gravitational waves (GW) to travel to both detectors corresponding to a source direction. Then the raw (observed) sky map of the SGWB is the signal convolved with a beam response function that varies with location in the sky. We first present a thorough analytic understanding of the structure of the beam response function using an analytic approach employing the stationary phase approximation. The true sky map is obtained by numerically deconvolving the beam function in the integral (convolution) equation. We adopt the maximum likelihood framework to estimate the true sky map using the conjugate gradient method that has been successfully used in the broadly similar, well-studied CMB map-making problem. We numerically implement and demonstrate the method on signal generated by simulated (unpolarized) SGWB for the GW radiometer consisting of the LIGO pair of detectors at Hanford and Livingston. We include 'realistic' additive Gaussian noise in each data stream based on the LIGO-I noise power spectral density. The extension of the method to multiple baselines and polarized GWB is outlined. In the near future the network of GW detectors, including the Advanced LIGO and Virgo detectors that will be sensitive to sources within a thousand times larger spatial volume, could provide promising data sets for GW radiometry.

Mitra, Sanjit [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India); Observatoire de la Cote d'Azur, BP 4229, 06304 Nice Cedex 4 (France); Dhurandhar, Sanjeev; Souradeep, Tarun [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India); Lazzarini, Albert; Mandic, Vuk; Ballmer, Stefan [LIGO Laboratory, California Institute of Technology, MS 18-34, Pasadena, California 91125 (United States); Bose, Sukanta [Department of Physics, Washington State University, Pullman, Washington 99164-2814 (United States)

2008-02-15T23:59:59.000Z

247

Gravitational waves from perturbed stars  

E-Print Network [OSTI]

Non radial oscillations of neutron stars are associated with the emission of gravitational waves. The characteristic frequencies of these oscillations can be computed using the theory of stellar perturbations, and they are shown to carry detailed information on the internal structure of the emitting source. Moreover, they appear to be encoded in various radiative processes, as for instance in the tail of the giant flares of Soft Gamma Repeaters. Thus, their determination is central to the theory of stellar perturbation. A viable approach to the problem consists in formulating this theory as a problem of resonant scattering of gravitational waves incident on the potential barrier generated by the spacetime curvature. This approach discloses some unexpected correspondences between the theory of stellar perturbations and the theory of quantum mechanics, and allows us to predict new relativistic effects.

Valeria Ferrari

2011-05-09T23:59:59.000Z

248

Progress towards Gravitational Wave Astronomy  

E-Print Network [OSTI]

I will review the most recent and interesting results from gravitational wave detection experiments, concentrating on recent results from the LIGO Scientific Collaboration (LSC). I will outline the methodologies utilized in the searches, explain what can be said in the case of a null result, what quantities may be constrained. I will compare these results with prior expectations and discuss their significance. As I go along I will outline the prospects for future improvements.

M. Alessandra Papa

2008-02-07T23:59:59.000Z

249

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

250

Weak Boson Emission in Hadron Collider Processes  

E-Print Network [OSTI]

The O(alpha) virtual weak radiative corrections to many hadron collider processes are known to become large and negative at high energies, due to the appearance of Sudakov-like logarithms. At the same order in perturbation theory, weak boson emission diagrams contribute. Since the W and Z bosons are massive, the O(alpha) virtual weak radiative corrections and the contributions from weak boson emission are separately finite. Thus, unlike in QED or QCD calculations, there is no technical reason for including gauge boson emission diagrams in calculations of electroweak radiative corrections. In most calculations of the O(alpha) electroweak radiative corrections, weak boson emission diagrams are therefore not taken into account. Another reason for not including these diagrams is that they lead to final states which differ from that of the original process. However, in experiment, one usually considers partially inclusive final states. Weak boson emission diagrams thus should be included in calculations of electroweak radiative corrections. In this paper, I examine the role of weak boson emission in those processes at the Fermilab Tevatron and the CERN LHC for which the one-loop electroweak radiative corrections are known to become large at high energies (inclusive jet, isolated photon, Z+1 jet, Drell-Yan, di-boson, t-bar t, and single top production). In general, I find that the cross section for weak boson emission is substantial at high energies and that weak boson emission and the O(alpha) virtual weak radiative corrections partially cancel.

U. Baur

2006-11-17T23:59:59.000Z

251

PROGRESS IN DESIGNING A MUON COOLING RING WITH LITHIUM LENSES.  

SciTech Connect (OSTI)

We discuss particle tracking simulations in a storage ring with lithium lens inserts designed for the six-dimensional phase space cooling of muons by the ionization cooling. The ring design contains one or more lithium lens absorbers for transverse cooling that transmit the beam with very small beta-function values, in addition to liquid-hydrogen wedge-shaped absorbers in dispersive locations for longitudinal cooling. Such a ring could comprise the final component of a cooling system for use in a muon collider. The beam matching between dipole-quadrupole lattices and the lithium lenses is of particular interest.

FUKUI,Y.CLINE,D.B.GARREN,A.A.KIRK,H.G.

2004-03-03T23:59:59.000Z

252

Optical loss due to diffraction by concentrator Fresnel lenses  

SciTech Connect (OSTI)

Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as a primary optical element. They focus sunlight on small solar cells or on the entrance apertures of secondary optical elements. A Fresnel lens consists of several prism rings and diffraction by these prism rings is unavoidable. Some of the light that would reach a designated target area according to geometric optics will miss it due to diffraction. This diffraction loss may be of relevant magnitude for CPV applications. The results of published analytical calculations are evaluated, discussed, and compared to computer simulations and measurements.

Hornung, Thorsten, E-mail: thorsten.hornung@ise.fraunhofer.de; Nitz, Peter, E-mail: thorsten.hornung@ise.fraunhofer.de [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg (Germany)

2014-09-26T23:59:59.000Z

253

The Nonlinear Essence of Gravitational Waves  

E-Print Network [OSTI]

A critical review of gravitational wave theory is made. It is pointed out that the usual linear approach to the gravitational wave theory is neither conceptually consistent nor mathematically justified. Relying upon that analysis it is then argued that -- analogously to a Yang-Mills propagating field, which must be nonlinear to carry its gauge charge -- a gravitational wave must necessarily be nonlinear to transport its own charge -- that is, energy-momentum.

R. Aldrovandi; J. G. Pereira; K. H. Vu

2007-09-11T23:59:59.000Z

254

Weak measurement and control of entanglement generation  

E-Print Network [OSTI]

In this paper we show how weak joint measurement and local feedback can be used to control entanglement generation between two qubits. To do this, we make use of a decoherence free subspace (DFS). Weak measurement and feedback can be used to drive the system into this subspace rapidly. Once within the subspace, feedback can generate entanglement rapidly, or turn off entanglement generation dynamically. We also consider, in the context of weak measurement, some of differences between purification and generating entanglement.

Charles D. Hill; J. F. Ralph

2008-01-28T23:59:59.000Z

255

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

256

Gravitational Phase Operator and Cosmic Strings  

E-Print Network [OSTI]

A quantum equivalence principle is formulated by means of a gravitational phase operator which is an element of the Poincare group. This is applied to the spinning cosmic string which suggests that it may (but not necessarily) contain gravitational torsion. A new exact solution of the Einstein- Cartan-Sciama-Kibble equations for the gravitational field with torsion is obtained everywhere for a cosmic string with uniform energy density, spin density and flux. A novel effect due to the quantized gravitational field of the cosmic string on the wave function of a particle outside the string is used to argue that spacetime points are not meaningful in quantum gravity.

J. Anandan

1995-12-14T23:59:59.000Z

257

Expanding the Area of Gravitational Entropy  

E-Print Network [OSTI]

I describe how gravitational entropy is intimately connected with the concept of gravitational heat, expressed as the difference between the total and free energies of a given gravitational system. From this perspective one can compute these thermodyanmic quantities in settings that go considerably beyond Bekenstein's original insight that the area of a black hole event horizon can be identified with thermodynamic entropy. The settings include the outsides of cosmological horizons and spacetimes with NUT charge. However the interpretation of gravitational entropy in these broader contexts remains to be understood.

R. B. Mann

2002-11-12T23:59:59.000Z

258

Inertia and gravitation in teleparallel gravity  

E-Print Network [OSTI]

Using the fact that teleparallel gravity allows a separation between gravitation and inertia, explicit expressions for the gravitational and the inertial energy-momentum densities are obtained. It is shown that, like all other fields of nature, gravitation alone has a tensorial energy-momentum density which in a general frame is conserved in the covariant sense. Together with the inertial energy-momentum density, they form a pseudotensor which is conserved in the ordinary sense. An analysis of the role played by the gravitational and the inertial densities in the computation of the total energy and momentum of gravity is presented.

R. Aldrovandi; Tiago Gribl Lucas; J. G. Pereira

2009-08-14T23:59:59.000Z

259

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 Mølmer

2009-11-13T23:59:59.000Z

260

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

2012-04-25T23:59:59.000Z

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

Geodesic and Path Motion in the Nonsymmetric Gravitational Theory  

E-Print Network [OSTI]

We study the problem of test-particle motion in the Nonsymmetric Gravitational Theory (NGT) assuming the four-velocity of the particle is parallel-transported along the trajectory. The predicted motion is studied on a static, spherically symmetric background field, with particular attention paid to radial and circular motions. Interestingly, it is found that the proper time taken to travel between any two non-zero radial positions is finite. It is also found that circular orbits can be supported at lower radii than in General Relativity for certain forms of motion. We present three interactions which could be used as alternate methods for coupling a test-particle to the antisymmetric components of the NGT field. One of these takes the form of a Yukawa force in the weak-field limit of a static, spherically symmetric field, which could lead to interesting phenomenology.

J. Legare; J. W. Moffat

1995-09-21T23:59:59.000Z

262

Gravitational duality and rotating solutions  

SciTech Connect (OSTI)

We study how gravitational duality acts on rotating solutions, using the Kerr-NUT black hole as an example. After properly reconsidering how to take into account both electric (i.e. masslike) and magnetic (i.e. NUT-like) sources in the equations of general relativity, we propose a set of definitions for the dual Lorentz charges. We then show that the Kerr-NUT solution has nontrivial such charges. Further, we clarify in which respect Kerr's source can be seen as a mass M with a dipole of NUT charges.

Argurio, Riccardo; Dehouck, Francois [Physique Theorique et Mathematique and International Solvay Institutes, Universite Libre de Bruxelles, C.P. 231, 1050 Bruxelles (Belgium)

2010-03-15T23:59:59.000Z

263

Geodesic deviation and gravitational waves  

E-Print Network [OSTI]

The detection of gravitational waves based on the geodesic deviation equation is discussed. In particular, it is shown that the only non-vanishing components of the wave field in the conventional traceless-transverse gauge in linearized general relativity do not enter the geodesic deviation equation, and therefore, apparently, no effect is predicted by that equation in that specific gauge. The reason is traced back to the fact that the geodesic deviation equation is written in terms of a coordinate distance, which is not a directly measurable quantity. On the other hand, in the proper Lorentz frame of the detector, the conventional result described in standard textbooks holds.

M. Leclerc

2006-05-24T23:59:59.000Z

264

Towards an Alternative Gravitational Theory  

E-Print Network [OSTI]

In 1680 Cassini proposed oval curves as alternative trajectories for the visible planets around the sun. The Cassini ovals were of course overshadow by the Kepler's first law (1609), namely the planets move around the sun describing conic orbits. Here we describe the possibility that the Cassini's idea works at larger or smaller scales. Indeed, we consider the Spiric curves (which are a generalization of the Cassini oval) and present the first steps towards a Spiric gravitational theory. We show that from our formalism an ellipse associated with a planet can be obtained as a particular case.

J. A. Nieto; L. A. Beltrán

2014-05-14T23:59:59.000Z

265

Gravitational waveforms with controlled accuracy  

E-Print Network [OSTI]

A partially first-order form of the characteristic formulation is introduced to control the accuracy in the computation of gravitational waveforms produced by highly distorted single black hole spacetimes. Our approach is to reduce the system of equations to first-order differential form on the angular derivatives, while retaining the proven radial and time integration schemes of the standard characteristic formulation. This results in significantly improved accuracy over the standard mixed-order approach in the extremely nonlinear post-merger regime of binary black hole collisions.

Roberto Gomez

2001-06-07T23:59:59.000Z

266

Subtraction-noise projection in gravitational-wave detector networks  

SciTech Connect (OSTI)

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

267

A New Type of X-ray Condenser Lenses with Large Apertures Fabricated by Rolling of Structured Films  

SciTech Connect (OSTI)

In order to meet the demand for X-ray lenses with large apertures and, hence, photon flux, a new type of X-ray lenses has been developed: Rolled prismatic X-ray lenses feature a vast number of refracting surfaces to increase transparency and aperture, respectively. Prototypes of such lenses have been fabricated by molding and rolling of a structured polyimide film. In this work, rolled prismatic X-ray lenses are pictured, and results of first tests performed at the ANKA storage ring in Karlsruhe are presented.

Simon, M.; Reznikova, E.; Nazmov, V.; Grund, T. [Institut fuer Mikrostrukturtechnik, Forschungszentrum Karlsruhe GmbH Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Last, A. [Institut fuer Mikrostrukturtechnik, Universitaet Karlsruhe Kaiserstrasse 12, 76131 Karlsruhe (Germany)

2010-04-06T23:59:59.000Z

268

SEEING AND COMMUNICATING THROUGH WEAK ELECTRIC  

E-Print Network [OSTI]

Inside JEB i SEEING AND COMMUNICATING THROUGH WEAK ELECTRIC FIELDS Weakly electric fish spend their lives bathed in their own internally generated mild electric field, interpreting perturbations frequency electric `chirps'. Rüdiger Krahe, from McGill University, Canada, says, `These fish are very

269

Gravitational force between two electrons in superconductors  

E-Print Network [OSTI]

The attractive gravitational force between two electrons in superconductors is deduced from the Eddington-Dirac large number relation, together with Beck and Mackey electromagnetic model of vacuum energy in superconductors. This force is estimated to be weaker than the gravitational attraction between two electrons in the vacuum.

Clovis Jacinto de Matos

2007-11-19T23:59:59.000Z

270

On multitemporal generalization of Newton's gravitational law  

E-Print Network [OSTI]

A n-time generalization of Newton's law (of universal gravitation) formula in N =n + d + 1-dimensional space-time is conjectured. This formula implies a relation for effective N-dimensional gravitational constant G_{eff} = G cos^2 \\theta, where \\theta is the angle between the direction of motion of two particles in n-dimensional time manifold R^n.

V. D. Ivashchuk

2009-05-15T23:59:59.000Z

271

Newtonian Constant of Gravitation International Consortium  

E-Print Network [OSTI]

Newtonian Constant of Gravitation International Consortium I. BACKGROUND Recent measurements of the Newtonian constant of gravitation G are in disagreement, with discrepancies that are roughly ten times forces on a laboratory scale. It also raises the question of whether the Newtonian force law

272

The wave function of a gravitating shell  

E-Print Network [OSTI]

We have calculated a discrete spectrum and found an exact analytical solution in the form of Meixner polynomials for the wave function of a thin gravitating shell in the Reissner-Nordstrom geometry. We show that there is no extreme state in the quantum spectrum of the gravitating shell, as in the case of extreme black hole.

V. I. Dokuchaev; S. V. Chernov

2010-10-01T23:59:59.000Z

273

Gravitational Waves in G4v  

E-Print Network [OSTI]

Gravitational coupling of the propagation four-vectors of matter wave functions is formulated in flat space-time. Coupling at the momentum level rather than at the "force-law" level greatly simplifies many calculations. This locally Lorentz-invariant approach (G4v) treats electromagnetic and gravitational coupling on an equal footing. Classical mechanics emerges from the incoherent aggregation of matter wave functions. The theory reproduces, to first order beyond Newton, the standard GR results for Gravity-Probe B, deflection of light by massive bodies, precession of orbits, gravitational red shift, and total gravitational-wave energy radiated by a circular binary system. Its predictions of total radiated energy from highly eccentric Kepler systems are slightly larger than those of similar GR treatments. G4v predictions differ markedly from those of GR for the gravitational-wave radiation patterns from rotating massive systems, and for the LIGO antenna pattern. The predicted antenna patterns have been shown t...

Mead, Carver

2015-01-01T23:59:59.000Z

274

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

275

High-resolution ALMA Observations of SDP.81. II. Molecular Clump Properties of a Lensed Submillimeter Galaxy at z=3.042  

E-Print Network [OSTI]

We present spatially-resolved properties of molecular gas and dust in a gravitationally-lensed submillimeter galaxy H-ATLAS J090311.6+003906 (SDP.81) at $z=3.042$ revealed by the Atacama Large Millimeter/submillimeter Array (ALMA). We identified 14 molecular clumps in the CO(5-4) line data, all with a spatial scale of $\\sim$50-300 pc in the source plane. The surface density of molecular gas ($\\Sigma_{\\rm H_2}$) and star-formation rate ($\\Sigma_{\\rm SFR}$) of the clumps are more than three orders of magnitude higher than those found in local spiral galaxies. The clumps are placed in the `burst' sequence in the $\\Sigma_{\\rm H_2}$-$\\Sigma_{\\rm SFR}$ plane, suggesting that $z \\sim 3$ molecular clumps follow the star-formation law derived for local starburst galaxies. With our gravitational lens model, the positions in the source plane are derived for the molecular clumps, dust clumps, and stellar components identified in the {\\sl Hubble Space Telescope} image. The molecular and dust clumps coexist in a similar re...

Hatsukade, Bunyo; Iono, Daisuke; Matsuda, Yuichi; Hayashi, Masao; Oguri, Masamune

2015-01-01T23:59:59.000Z

276

Weak Charge of 133 Walter Johnson  

E-Print Network [OSTI]

Atomic PNC and the Weak Charge of 133 Cs Walter Johnson Department of Physics Notre Dame University http://www.nd.edu/johnson June 21, 2002 Abstract Atomic PNC measurements and calculations are reviewed

Johnson, Walter R.

277

Can the trace formula describe weak localisation?  

E-Print Network [OSTI]

We attempt to systematically derive perturbative quantum corrections to the Berry diagonal approximation of the two-level correlation function (TLCF) for chaotic systems. To this end, we develop a ``weak diagonal approximation'' based on a recent description of the first weak localisation correction to conductance in terms of the Gutzwiller trace formula. This semiclassical method is tested by using it to derive the weak localisation corrections to the TLCF for a semiclassically disordered system. Unfortunately the method is unable to correctly reproduce the ``Hikami boxes'' (the relatively small regions where classical paths are glued together by quantum processes). This results in the method failing to reproduce the well known weak localisation expansion. It so happens that for the first order correction it merely produces the wrong prefactor. However for the second order correction, it is unable to reproduce certain contributions, and leads to a result which is of a different form to the standard one.

Robert S. Whitney; Igor V. Lerner; Robert A. Smith

1999-02-24T23:59:59.000Z

278

Project title: Novel liquid crystal lenses Project Supervisors: Prof Helen Gleeson & Dr Philip Morgan, University of  

E-Print Network [OSTI]

Project title: Novel liquid crystal lenses Project Supervisors: Prof Helen Gleeson & Dr Philip Morgan, University of Manchester Project Sponsors: EPSRC and Ultravision i.e. the project is a CASE award. Only applicants who satisfy

279

Krill-eye : Superposition Compound Eye for Wide-Angle Imaging via GRIN Lenses  

E-Print Network [OSTI]

We propose a novel wide angle imaging system inspired by compound eyes of animals. Instead of using a single lens, well compensated for aberration, we used a number of simple lenses to form a compound eye which produces ...

Hiura, Shinsaku

280

3D spectroscopy as a tool for investigation of the BLR of lensed QSOs  

E-Print Network [OSTI]

Selective amplification of the line and continuum source by microlensing in a lensed quasar can lead to changes of continuum spectral slopes and line shapes in the spectra of the quasar components. Comparing the spectra of different components of the lensed quasar and the spectra of an image observed in different epochs one can infer the presence of millilensing, microlensing and intrinsic variability. Especially, microlensing can be used for investigation of the unresolved broad line (BLR) and continuum emitting region structure in active galactic nuclei (AGN). Therefore the spectroscopic monitoring of selected lensed quasars with 3D spectroscopy open new possibility for investigation of the BLR structure in AGN. Here we discuss observational effects that may be present during the BLR microlensing in the spectra of lensed QSOs.

L. C. Popovic

2005-12-23T23:59:59.000Z

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.


281

A weak acceleration effect due to residual gravity in a multiply connected universe  

E-Print Network [OSTI]

Could cosmic topology imply dark energy? We use a weak field (Newtonian) approximation of gravity and consider the gravitational effect from distant, multiple copies of a large, collapsed (virialised) object today (i.e. a massive galaxy cluster), taking into account the finite propagation speed of gravity, in a flat, multiply connected universe, and assume that due to a prior epoch of fast expansion (e.g. inflation), the gravitational effect of the distant copies is felt locally, from beyond the naively calculated horizon. We find that for a universe with a $T^1xR^2$ spatial section, the residual Newtonian gravitational force (to first order) provides an anisotropic effect that repels test particles from the cluster in the compact direction, in a way algebraically similar to that of dark energy. For a typical test object at comoving distance $\\chi$ from the nearest dense nodes of the cosmic web of density perturbations, the pressure-to-density ratio $w$ of the equation of state in an FLRW universe, is w \\sim - (\\chi/L)^3, where $L$ is the size of the fundamental domain, i.e. of the universe. Clearly, |w|dark energy, but the amplitude of the effect at the present epoch is too small to explain the observed dark energy density and its anisotropy makes it an unrealistic candidate for the observed dark energy.

Boudewijn F. Roukema; Stanislaw Bajtlik; Marek Biesiada; Agnieszka Szaniewska; Helena Jurkiewicz

2006-12-08T23:59:59.000Z

282

Gravitational Radiation and Very Long Baseline Interferometry  

E-Print Network [OSTI]

Gravitational waves affect the observed direction of light from distant sources. At telescopes, this change in direction appears as periodic variations in the apparent positions of these sources on the sky; that is, as proper motion. A wave of a given phase, traveling in a given direction, produces a characteristic pattern of proper motions over the sky. Comparison of observed proper motions with this pattern serves to test for the presence of gravitational waves. A stochastic background of waves induces apparent proper motions with specific statistical properties, and so, may also be sought. In this paper we consider the effects of a cosmological background of gravitational radiation on astrometric observations. We derive an equation for the time delay measured by two antennae observing the same source in an Einstein-de Sitter spacetime containing gravitational radiation. We also show how to obtain similar expressions for curved Friedmann-Robertson-Walker spacetimes.

Ted Pyne; Carl R. Gwinn; Mark Birkinshaw; T. Marshall Eubanks; Demetrios N. Matsakis

1995-07-10T23:59:59.000Z

283

Planet migration in self-gravitating disks  

E-Print Network [OSTI]

and migration of the planet at the same time so that theG. W. 1978, Moon and Planets, 18, 5 Fukagawa, M. , Hayashi,Planet migration in self-gravitating protoplanetary discs

Meru, Farzana; Baruteau, Clement

2010-01-01T23:59:59.000Z

284

Concepts of Intertial and Gravitational Mass  

E-Print Network [OSTI]

The general relativistic notion of gravitational and inertial mass is discussed from the general viewpoint of the tidal forces implicit in the curvature and the Einstein field equations within ponderable matter. A simple yet rigorously general derivation is given for the Tolman gravitational mass viewpoint wherein the computation of gravitational mass requires both a rest energy contribution (the inertial mass) and a pressure contribution. The pressure contribution is extremely small under normal conditions which implies the equality of gravitational and inertial mass to a high degree of accuracy. However, the pressure contribution is substantial for conformal symmetric systems such as Maxwell radiation, whose constituent photons are massless. Implications of the Tolman mass for standard cosmology and standard high energy particle physics models are briefly explored.

A. Widom

2006-06-17T23:59:59.000Z

285

Strings in plane-fronted gravitational waves  

E-Print Network [OSTI]

Brinkmann's plane-fronted gravitational waves with parallel rays --~shortly pp-waves~-- are shown to provide, under suitable conditions, exact string vacua at all orders of the sigma-model perturbation expansion.

C. Duval; Z. Horvath; P. A. Horvathy

2006-02-13T23:59:59.000Z

286

Atom Interferometers and the Gravitational Redshift  

E-Print Network [OSTI]

From the principle of equivalence, Einstein predicted that clocks slow down in a gravitational field. Since the general theory of relativity is based on the principle of equivalence, it is essential to test this prediction accurately. Muller, Peters and Chu claim that a reinterpretation of decade old experiments with atom interferometers leads to a sensitive test of this gravitational redshift effect at the Compton frequency. Wolf et al dispute this claim and adduce arguments against it. In this article, we distill these arguments to a single fundamental objection: an atom is NOT a clock ticking at the Compton frequency. We conclude that atom interferometry experiments conducted to date do not yield such sensitive tests of the gravitational redshift. Finally, we suggest a new interferometric experiment to measure the gravitational redshift, which realises a quantum version of the classical clock "paradox".

Supurna Sinha; Joseph Samuel

2011-05-16T23:59:59.000Z

287

Sources of Gravitational Waves: Theory and Observations  

E-Print Network [OSTI]

Gravitational-wave astronomy will soon become a new tool for observing the Universe. Detecting and interpreting gravitational waves will require deep theoretical insights into astronomical sources. The past three decades have seen remarkable progress in analytical and numerical computations of the source dynamics, development of search algorithms and analysis of data from detectors with unprecedented sensitivity. This Chapter is devoted to examine the advances and future challenges in understanding the dynamics of binary and isolated compact-object systems, expected cosmological sources, their amplitudes and rates, and highlights of results from gravitational-wave observations. All of this is a testament to the readiness of the community to open a new window for observing the cosmos, a century after gravitational waves were first predicted by Albert Einstein.

Alessandra Buonanno; B. S. Sathyaprakash

2014-10-28T23:59:59.000Z

288

Environmental Effects for Gravitational-wave Astrophysics  

E-Print Network [OSTI]

The upcoming detection of gravitational waves by terrestrial interferometers will usher in the era of gravitational-wave astronomy. This will be particularly true when space-based detectors will come of age and measure the mass and spin of massive black holes with exquisite precision and up to very high redshifts, thus allowing for better understanding of the symbiotic evolution of black holes with galaxies, and for high-precision tests of General Relativity in strong-field, highly-dynamical regimes. Such ambitious goals require that astrophysical environmental pollution of gravitational-wave signals be constrained to negligible levels, so that neither detection nor estimation of the source parameters are significantly affected. Here, we consider the main sources for space-based detectors -the inspiral, merger and ringdown of massive black-hole binaries and extreme mass-ratio inspirals- and account for various effects on their gravitational waveforms, including electromagnetic fields, cosmological evolution, ...

Barausse, Enrico; Pani, Paolo

2014-01-01T23:59:59.000Z

289

Gravitational clustering in Static and Expanding Backgrounds  

E-Print Network [OSTI]

A brief summary of several topics in the study of gravitational many body problem is given. The discussion covers both static backgrounds (applicable to astrophysical systems) as well as clustering in an expanding background (relevant for cosmology)

T. Padmanabhan

2003-08-28T23:59:59.000Z

290

Propagation of gravitational waves in multimetric gravity  

E-Print Network [OSTI]

We discuss the propagation of gravitational waves in a recently discussed class of theories containing N >= 2 metric tensors and a corresponding number of standard model copies. Using the formalism of gauge-invariant linear perturbation theory we show that all gravitational waves propagate at the speed of light. We then employ the Newman-Penrose formalism to show that two to six polarizations of gravitational waves may exist, depending on the parameters entering the equations of motion. This corresponds to E(2) representations N_2, N_3, III_5 and II_6. We finally apply our general discussion to a recently presented concrete multimetric gravity model and show that it is of class N_2, i.e., it allows only two tensor polarizations, as it is the case for general relativity. Our results provide the theoretical background for tests of multimetric gravity theories using the upcoming gravitational wave experiments.

Manuel Hohmann

2012-04-22T23:59:59.000Z

291

Power recycling for an interferometric gravitational wave  

E-Print Network [OSTI]

THESIS Power recycling for an interferometric gravitational wave detector Masaki Ando Department . . . . . . . . . . . . . . 48 3.3 Power recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.3.1 Principle of power recycling . . . . . . . . . . . . . . . . . 50 3.3.2 Recycling cavity

Ejiri, Shinji

292

Resonant speed meter for gravitational wave detection  

E-Print Network [OSTI]

Gravitational-wave detectors have been well developed and operated with high sensitivity. However, they still suffer from mirror displacement noise. In this paper, we propose a resonant speed meter, as a displacement noise-canceled configuration based on a ring-shaped synchronous recycling interferometer. The remarkable feature of this interferometer is that, at certain frequencies, gravitational-wave signals are amplified, while displacement noises are not.

Atsushi Nishizawa; Seiji Kawamura; Masa-aki Sakagami

2008-05-01T23:59:59.000Z

293

Spin-2 particles in gravitational fields  

E-Print Network [OSTI]

We give a solution of the wave equation for massless, or massive spin-2 particles propagating in a gravitational background. The solution is covariant, gauge-invariant and exact to first order in the background gravitational field. The background contribution is confined to a phase factor from which geometrical and physical optics can be derived. The phase also describes Mashhoon's spin-rotation coupling and, in general, the spin-gravity interaction.

G. Papini

2007-02-01T23:59:59.000Z

294

Testing Modified Gravity with Gravitational Wave Astronomy  

E-Print Network [OSTI]

The emergent area of gravitational wave astronomy promises to provide revolutionary discoveries in the areas of astrophysics, cosmology, and fundamental physics. One of the most exciting possibilities is to use gravitational-wave observations to test alternative theories of gravity. In this contribution we describe how to use observations of extreme-mass-ratio inspirals by the future Laser Interferometer Space Antenna to test a particular class of theories: Chern-Simons modified gravity.

Carlos F. Sopuerta; Nicolas Yunes

2010-10-01T23:59:59.000Z

295

Gravitational Waves in G4v  

E-Print Network [OSTI]

Gravitational coupling of the propagation four-vectors of matter wave functions is formulated in flat space-time. Coupling at the momentum level rather than at the "force-law" level greatly simplifies many calculations. This locally Lorentz-invariant approach (G4v) treats electromagnetic and gravitational coupling on an equal footing. Classical mechanics emerges from the incoherent aggregation of matter wave functions. The theory reproduces, to first order beyond Newton, the standard GR results for Gravity-Probe B, deflection of light by massive bodies, precession of orbits, gravitational red shift, and total gravitational-wave energy radiated by a circular binary system. Its predictions of total radiated energy from highly eccentric Kepler systems are slightly larger than those of similar GR treatments. G4v predictions differ markedly from those of GR for the gravitational-wave radiation patterns from rotating massive systems, and for the LIGO antenna pattern. The predicted antenna patterns have been shown to be highly distinguishable in the case of continuous gravitational-wave sources, and should therefore be testable as data from Advanced LIGO becomes available over the next few years.

Carver Mead

2015-03-16T23:59:59.000Z

296

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

297

Theory and Modeling of Weakly Bound/Physisorbed Materials for...  

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

Theory and Modeling of Weakly BoundPhysisorbed Materials for Hydrogen Storage Theory and Modeling of Weakly BoundPhysisorbed Materials for Hydrogen Storage Presentation on the...

298

Contribution of muscular weakness to osteoporosis: Computational and animal models  

E-Print Network [OSTI]

Contribution of muscular weakness to osteoporosis: Computational and animal models M. Be obtained herein indicate that muscular weakness may be an important factor contributing to osteoporosis. Ó

Gefen, Amit

299

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

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

8: Apache Tomcat HTTP DIGEST Authentication Weaknesses Let Remote Users Conduct Bypass Attacks T-728: Apache Tomcat HTTP DIGEST Authentication Weaknesses Let Remote Users Conduct...

300

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

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

5: Linux Kernel Weakness in Sequence Number Generation Facilitates Packet Injection Attacks T-705: Linux Kernel Weakness in Sequence Number Generation Facilitates Packet Injection...

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.


301

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

302

No-Hair Theorem for Weak Pulsar  

E-Print Network [OSTI]

It is proposed that there exists a class of pulsars, called weak pulsars, for which the large-scale magnetosphere, and hence the gamma-ray emission, are independent of the detailed pattern of plasma production. The weak pulsar magnetosphere and its gamma-ray emission are uniquely determined by just three parameters: spin, dipole, and the spin-dipole angle. We calculate this supposedly unique pulsar magnetosphere in the axisymmetric case. The magnetosphere is found to be very close to (although interestingly not fully identical with) the magnetosphere we have previously calculated, explaining the phenomenological success of the old calculation. We offer only a highly tentative proof of this "Pulsar No-Hair Theorem". Our analytics, while convincing in its non-triviality, is incomplete, and counts only as a plausibility argument. Our numerics, while complete, is dubious. The plasma flow in the weak pulsar magnetosphere turns out to be even more intricate than what we have previously proposed: some particles, aft...

Gruzinov, Andrei

2015-01-01T23:59:59.000Z

303

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

304

Crossover between weak localization and weak antilocalization in magnetically doped topological insulator  

E-Print Network [OSTI]

;Topological insulators (TI) are a new class of quantum materials with insulating bulk enclosedCrossover between weak localization and weak antilocalization in magnetically doped topological insulator Minhao Liu1,* , Jinsong Zhang1,* , Cui-Zu Chang1,2,* , Zuocheng Zhang1 , Xiao Feng2 , Kang Li2

Wang, Wei Hua

305

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

2006-08-02T23:59:59.000Z

306

E-Print Network 3.0 - advanced gravitational wave Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

gravitational wave Search Powered by Explorit Topic List Advanced Search Sample search results for: advanced gravitational wave Page: << < 1 2 3 4 5 > >> 1 Gravitational waves...

307

Energy Contents of Gravitational Waves in Teleparallel Gravity  

E-Print Network [OSTI]

The conserved quantities, that are, gravitational energy-momentum and its relevant quantities are investigated for cylindrical and spherical gravitational waves in the framework of teleparallel equivalent of General Relativity using the Hamiltonian approach. For both cylindrical and spherical gravitational waves, we obtain definite energy and constant momentum. The constant momentum shows consistency with the results available in General Relativity and teleparallel gravity. The angular momentum for cylindrical and spherical gravitational waves also turn out to be constant. Further, we evaluate their gravitational energy-momentum fluxes and gravitational pressure.

M. Sharif; Sumaira Taj

2009-10-02T23:59:59.000Z

308

129A Lecture Notes Weak Interactions I  

E-Print Network [OSTI]

129A Lecture Notes Weak Interactions I 1 Nuclear -decay The nuclear -decay caused a great deal of nuclear fission, studied the spectrum and claimed that it was discrete. They argued that the spectrum may have hit upon a desperate remedy to save the "exchange theorem" of statistics and the law

Murayama, Hitoshi

309

Products, weak topologies, quotients and strong topologies.  

E-Print Network [OSTI]

Products, weak topologies, quotients and strong topologies. Stefano Ferri Abstract Again something from finite products of metric spaces, which are well known from the course Analysis I. Given two metric spaces (X, d) and (Y, ) we define the product space X Ã? Y in the following way. As a set we have

Ferri, Stefano

310

Quantum Trajectories based on the Weak Value  

E-Print Network [OSTI]

The notion of trajectory of an individual particle is strictly inhibited in quantum mechanics because of the uncertainty principle. Nonetheless, the weak value, which has been proposed as a novel and measurable quantity definable to any quantum observable, can offer a possible description of trajectory on account of its statistical nature of the value. In this paper, we explore the physical significance provided by this weak trajectory by considering various situations where interference takes place simultaneously with the observation of particles, that is, in prototypical quantum situations for which no classical treatment is available. These include the double slit experiment and Lloyd's mirror, where in the former case it is argued that the real part of the weak trajectory describes an average over the possible classical trajectories involved in the process, and that the imaginary part is related to the variation of interference. It is shown that this average interpretation of the weak trajectory holds universally under the complex probability defined from the given transition process. These features remain essentially unaltered in the case of Lloyd's mirror where interference occurs with a single slit.

Takuya Mori; Izumi Tsutsui

2014-12-02T23:59:59.000Z

311

Reversing entanglement change by a weak measurement  

E-Print Network [OSTI]

PHYSICAL REVIEW A 82, 052323 (2010) Reversing entanglement change by a weak measurement Qingqing Sun,1,* M. Al-Amri,2 Luiz Davidovich,3 and M. Suhail Zubairy1 1Department of Physics and Institute for Quantum Science and Engineering, Texas A...

Sun, Qingqing; Al-Amri, M.; Davidovich, Luiz; Zubairy, M. Suhail.

2010-01-01T23:59:59.000Z

312

The gravitational wave symphony of the Universe  

E-Print Network [OSTI]

The new millennium will see the upcoming of several ground-based interferometric gravitational wave antennas. Within the next decade a space-based antenna may also begin to observe the distant Universe. These gravitational wave detectors will together operate as a network taking data continuously for several years, watching the transient and continuous phenomena occurring in the deep cores of astronomical objects and dense environs of the early Universe where gravity was extremely strong and highly non-linear. The network will listen to the waves from rapidly spinning non-axisymmetric neutron stars, normal modes of black holes, binary black hole inspiral and merger, phase transitions in the early Universe, quantum fluctuations resulting in a characteristic background in the early Universe. The gravitational wave antennas will open a new window to observe the dark Universe unreachable via other channels of astronomical observations.

B. S. Sathyaprakash

2002-07-10T23:59:59.000Z

313

Statistical mechanics of gravitating systems: An Overview  

E-Print Network [OSTI]

I review several issues related to statistical description of gravitating systems in both static and expanding backgrounds. After briefly reviewing the results for the static background, I concentrate on gravitational clustering of collisionless particles in an expanding universe. In particular, I describe (a) how the non linear mode-mode coupling transfers power from one scale to another in the Fourier space if the initial power spectrum is sharply peaked at a given scale and (b) the asymptotic characteristics of gravitational clustering which are independent of the initial conditions. Numerical simulations as well as analytic work shows that power transfer leads to a universal power spectrum at late times, somewhat reminiscent of the existence of Kolmogorov spectrum in fluid turbulence.

T. Padmanabhan

2009-02-16T23:59:59.000Z

314

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

2012-05-11T23:59:59.000Z

315

Gravitational Mass, Its Mechanics - What It Is; How It Operates  

E-Print Network [OSTI]

The earlier paper, Inertial Mass, Its Mechanics - What It Is; How It Operates, developed the mechanics of inertial mass. The present paper is for the purpose of equivalently developing gravitation. The behavior of gravitation is well known, as described by Newton's Law of Gravitation. But just what gravitational mass is, how gravitational behavior comes about, what in material reality produces the effects of gravitational mass, has been little understood. The only extant hypotheses involve the unsuccessful efforts to develop "quantum gravitation" and to tie it into the rest of quantum mechanics, and the equally failed attempts to detect "gravitons" and "gravitational waves" in spite of very substantial efforts. From a starting point of only the limitation on the speed of light, the necessity of conservation, and the impossibility of an infinity in material reality, the present paper presents a new and comprehensive analysis of the phenomenon gravitational mass: - how it appears in particles, - how the Newtonian gravitational behavior arises from that, and - how the values of inertial mass and gravitational mass are identical, or, in other words, the mechanics of gravitational mass and gravitation.

Roger Ellman

2006-03-06T23:59:59.000Z

316

Environmental Effects for Gravitational-wave Astrophysics  

E-Print Network [OSTI]

The upcoming detection of gravitational waves by terrestrial interferometers will usher in the era of gravitational-wave astronomy. This will be particularly true when space-based detectors will come of age and measure the mass and spin of massive black holes with exquisite precision and up to very high redshifts, thus allowing for better understanding of the symbiotic evolution of black holes with galaxies, and for high-precision tests of General Relativity in strong-field, highly dynamical regimes. Such ambitious goals require that astrophysical environmental pollution of gravitational-wave signals be constrained to negligible levels, so that neither detection nor estimation of the source parameters are significantly affected. Here, we consider the main sources for space-based detectors -- the inspiral, merger and ringdown of massive black-hole binaries and extreme mass-ratio inspirals -- and account for various effects on their gravitational waveforms, including electromagnetic fields, cosmological evolution, accretion disks, dark matter, "firewalls" and possible deviations from General Relativity. We discover that the black-hole quasinormal modes are sharply different in the presence of matter, but the ringdown signal observed by interferometers is typically unaffected. The effect of accretion disks and dark matter depends critically on their geometry and density profile, but is negligible for most sources, except for few special extreme mass-ratio inspirals. Electromagnetic fields and cosmological effects are always negligible. We finally explore the implications of our findings for proposed tests of General Relativity with gravitational waves, and conclude that environmental effects will not prevent the development of precision gravitational-wave astronomy.

Enrico Barausse; Vitor Cardoso; Paolo Pani

2015-01-07T23:59:59.000Z

317

Do Mirrors for Gravitational Waves Exist?  

E-Print Network [OSTI]

Thin superconducting films are predicted to be highly reflective mirrors for gravitational waves at microwave frequencies. The quantum mechanical non-localizability of the negatively charged Cooper pairs, which is protected from the localizing effect of decoherence by an energy gap, causes the pairs to undergo non-picturable, non-geodesic motion in the presence of a gravitational wave. This non-geodesic motion, which is accelerated motion through space, leads to the existence of mass and charge supercurrents inside the superconducting film. On the other hand, the decoherence-induced localizability of the positively charged ions in the lattice causes them to undergo picturable, geodesic motion as they are carried along with space in the presence of the same gravitational wave. The resulting separation of charges leads to a virtual plasma excitation within the film that enormously enhances its interaction with the wave, relative to that of a neutral superfluid or any normal matter. The existence of strong mass supercurrents within a superconducting film in the presence of a gravitational wave, dubbed the "Heisenberg-Coulomb effect," implies the specular reflection of a gravitational microwave from a film whose thickness is much less than the London penetration depth of the material, in close analogy with the electromagnetic case. The argument is developed by allowing classical gravitational fields, which obey Maxwell-like equations, to interact with quantum matter, which is described using the BCS and Ginzburg-Landau theories of superconductivity, as well as a collisionless plasma model. Several possible experimental tests of these ideas, including mesoscopic ones, are presented alongside comments on the broader theoretical implications of the central hypothesis.

Stephen J. Minter; Kirk Wegter-McNelly; Raymond Y. Chiao

2009-06-30T23:59:59.000Z

318

Electromagnetic waves, gravitational coupling and duality analysis  

E-Print Network [OSTI]

In this letter we introduce a particular solution for parallel electric and magnetic fields, in a gravitational background, which satisfy free-wave equations and the phenomenology suggested by astrophysical plasma physics. These free-wave equations are computed such that the electric field does not induce the magnetic field and vice-versa. In a gravitational field, we analyze the Maxwell equations and the corresponding electromagnetic waves. A continuity equation is presented. A commutative and noncommutative analysis of the electromagnetic duality is described.

E. M. C. Abreu; C. Pinheiro; S. A. Diniz; F. C. Khanna

2005-10-27T23:59:59.000Z

319

ngravs: Distinct gravitational interactions in GADGET-2  

E-Print Network [OSTI]

We discuss an extension of the massively parallel cosmological simulation code GADGET-2, which enables investigation of distinct gravitational force laws between particle species. In addition to simplifying investigations of a universally modified force law, the ngravs extension allows state-of-the-art collisionless cosmological simulations of quite exotic gravitational scenarios. We briefly review the algorithms used by GADGET-2, and present our extension to multiple gravities, highlighting additional features that facilitate consideration of exotic force laws. We discuss the accuracy and performance of the ngravs extension, both internally and with an unaltered GADGET-2, under all relevant operational modes. The ngravs extension is publicly released to the research community.

Croker, K A S

2015-01-01T23:59:59.000Z

320

Energy-Momentum and Angular Momentum Carried by Gravitational Waves in Extended New General Relativity  

E-Print Network [OSTI]

In an extended, new form of general relativity, which is a teleparallel theory of gravity, we examine the energy-momentum and angular momentum carried by gravitational wave radiated from Newtonian point masses in a weak-field approximation. The resulting wave form is identical to the corresponding wave form in general relativity, which is consistent with previous results in teleparallel theory. The expression for the dynamical energy-momentum density is identical to that for the canonical energy-momentum density in general relativity up to leading order terms on the boundary of a large sphere including the gravitational source, and the loss of dynamical energy-momentum, which is the generator of \\emph{internal} translations, is the same as that of the canonical energy-momentum in general relativity. Under certain asymptotic conditions for a non-dynamical Higgs-type field $\\psi^{k}$, the loss of ``spin'' angular momentum, which is the generator of \\emph{internal} $SL(2,C)$ transformations, is the same as that of angular momentum in general relativity, and the losses of canonical energy-momentum and orbital angular momentum, which constitute the generator of Poincar\\'{e} \\emph{coordinate} transformations, are vanishing. The results indicate that our definitions of the dynamical energy-momentum and angular momentum densities in this extended new general relativity work well for gravitational wave radiations, and the extended new general relativity accounts for the Hulse-Taylor measurement of the pulsar PSR1913+16.

Eisaku Sakane; Toshiharu Kawai

2002-09-30T23:59:59.000Z

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

The impact of thermodynamics on gravitational collapse: filament formation and magnetic field amplification  

E-Print Network [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^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.

Thomas Peters; Dominik R. G. Schleicher; Ralf S. Klessen; Robi Banerjee; Christoph Federrath; Rowan J. Smith; Sharanya Sur

2012-09-26T23:59:59.000Z

322

A "Lorentz-Poincare"-Type Interpretation of Relativistic Gravitation  

E-Print Network [OSTI]

The nature of 'time', 'space' and 'reality' are to large extent dependent on our interpretation of Special (SRT) and General Relativity Theory (GRT). In SRT essentially two distinct interpretations exist; the "geometrical" interpretation by Einstein based on the Principle of Relativity and the Invariance of the velocity of light and, the "physical" Lorentz-Poincar\\'e interpretation with underpinning by rod contractions, clock slowing and light synchronization, see e.g. (Bohm 1965, Bell 1987). It can be questioned whether the "Lorentz-Poincar\\'e"-interpretation of SRT can be continued into GRT. We have shown that till first Post-Newtonian order this is indeed possible (Broekaert 2004). This requires the introduction of gravitationally modified Lorentz transformations, with an intrinsical spatially-variable speed of light $c(r)$, a scalar scaling field $\\Phi$ and induced velocity field $w$. Still the invariance of the locally observed velocity of light is maintained (Broekaert 2005). The Hamiltonian description of particles and photons recovers the 1-PN approximation of GRT. At present we show the model does obey the Weak Equivalence Principle from a fixed perspective, and that the implied acceleration transformations are equivalent with those of GRT.

Jan; Broekaert

2005-10-05T23:59:59.000Z

323

Initial data for Einstein's equations with superposed gravitational waves  

E-Print Network [OSTI]

A method is presented to construct initial data for Einstein's equations as a superposition of a gravitational wave perturbation on an arbitrary stationary background spacetime. The method combines the conformal thin sandwich formalism with linear gravitational waves, and allows detailed control over characteristics of the superposed gravitational wave like shape, location and propagation direction. It is furthermore fully covariant with respect to spatial coordinate changes and allows for very large amplitude of the gravitational wave.

Harald P. Pfeiffer; Lawrence E. Kidder; Mark A. Scheel; Deirdre Shoemaker

2005-02-22T23:59:59.000Z

324

The performance of the corrector lenses for the Auger fluorescence detector  

SciTech Connect (OSTI)

We present an analysis of the effect that the corrector lenses (Schmidt Optics) have on the overall performance of the Auger Fluorescence Detector. The analysis uses real data from the telescopes. Figures of merit for the corrector lenses performance include shower trigger rate and the distribution of the distance of closest approach to the shower axis. As a result of this analysis we may say that the effective light collection area of a telescope nearly doubles with the use of a corrector lens at its aperture.

Sato, Ricardo; Escobar, Carlos O.; /Campinas State U.

2005-07-01T23:59:59.000Z

325

Weakly nonlocal fluid mechanics - the Schrodinger equation  

E-Print Network [OSTI]

A weakly nonlocal extension of ideal fluid dynamics is derived from the Second Law of thermodynamics. It is proved that in the reversible limit the additional pressure term can be derived from a potential. The requirement of the additivity of the specific entropy function determines the quantum potential uniquely. The relation to other known derivations of Schr\\"odinger equation (stochastic, Fisher information, exact uncertainty) is clarified.

P. Van; T. Fulop

2004-06-09T23:59:59.000Z

326

INVERSE-SQUARE LAW TESTS 1 TESTS OF THE GRAVITATIONAL  

E-Print Network [OSTI]

INVERSE-SQUARE LAW TESTS 1 TESTS OF THE GRAVITATIONAL INVERSE-SQUARE LAW E.G.Adelberger, B-1560 KEYWORDS: gravitation, experimental tests of inverse-square law, quantum gravity, extra dimensions ABSTRACT: We review recent experimental tests of the gravitational inverse-square law, and the wide variety

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

327

Relic gravitational waves and the generalized second law  

E-Print Network [OSTI]

The generalized second law of gravitational thermodynamics is applied to the present era of accelerated expansion of the Universe. In spite of the fact that the entropy of matter and relic gravitational waves inside the event horizon diminish, the mentioned law is fulfilled provided that the expression for the entropy density of the gravitational waves satisfies a certain condition.

German Izquierdo; Diego Pavon

2005-01-12T23:59:59.000Z

328

Heating Cooling Flows with Weak Shock Waves  

E-Print Network [OSTI]

The discovery of extended, approximately spherical weak shock waves in the hot intercluster gas in Perseus and Virgo has precipitated the notion that these waves may be the primary heating process that explains why so little gas cools to low temperatures. This type of heating has received additional support from recent gasdynamical models. We show here that outward propagating, dissipating waves deposit most of their energy near the center of the cluster atmosphere. Consequently, if the gas is heated by (intermittent) weak shocks for several Gyrs, the gas within 30-50 kpc is heated to temperatures that far exceed observed values. This heating can be avoided if dissipating shocks are sufficiently infrequent or weak so as not to be the primary source of global heating. Local PV and viscous heating associated with newly formed X-ray cavities are likely to be small, which is consistent with the low gas temperatures generally observed near the centers of groups and clusters where the cavities are located.

W. G. Mathews; A. Faltenbacher; F. Brighenti

2005-11-05T23:59:59.000Z

329

The role of the quantum properties of gravitational radiation in the dete ction of gravitational waves  

E-Print Network [OSTI]

The role that the quantum properties of a gravitational wave could play in the detection of gravitational radiation is analyzed. It is not only corroborated that in the current laser-interferometric detectors the resolution of the experimental apparatus could lie very far from the corresponding quantum threshold (thus the backreaction effect of the measuring device upon the gravitational wave is negligible), but it is also suggested that the consideration of the quantum properties of the wave could entail the definition of dispersion of the measurement outputs. This dispersion would be a function not only of the sensitivity of the measuring device, but also of the interaction time (between measuring device and gravitational radiation) and of the arm length of the corresponding laser- interferometer. It would have a minimum limit, and the introduction of the current experimental parameters insinuates that the dispersion of the existing proposals could lie very far from this minimum, which means that they would show a very large dispersion.

A. Camacho

1998-07-10T23:59:59.000Z

330

Gravitational Bending of Light with Frequency Shifts  

E-Print Network [OSTI]

Non-static gravitational fields generally introduce frequency shifts when bending light. In this paper, I discuss the frequency shifts induced in the bending of light by moving masses. As examples, I treat the recently discovered high-velocity pulsar PSR 2224+65 and a typical Einstein ring.

P. D. Morley

1993-11-15T23:59:59.000Z

331

Interaction of Gravitational Waves with Charged Particles  

E-Print Network [OSTI]

It is shown here that a cloud of charged particles could in principle absorb energy from gravitational waves (GWs) incident upon it, resulting in wave attenuation. This could in turn have implications for the interpretation of future data from early universe GWs.

Thulsi Wickramasinghe; Will Rhodes; Mitchell Revalski

2015-02-03T23:59:59.000Z

332

Gravitational waves from rapidly rotating neutron stars  

E-Print Network [OSTI]

Rapidly rotating neutron stars in Low Mass X-ray Binaries have been proposed as an interesting source of gravitational waves. In this chapter we present estimates of the gravitational wave emission for various scenarios, given the (electromagnetically) observed characteristics of these systems. First of all we focus on the r-mode instability and show that a 'minimal' neutron star model (which does not incorporate exotica in the core, dynamically important magnetic fields or superfluid degrees of freedom), is not consistent with observations. We then present estimates of both thermally induced and magnetically sustained mountains in the crust. In general magnetic mountains are likely to be detectable only if the buried magnetic field of the star is of the order of $B\\approx 10^{12}$ G. In the thermal mountain case we find that gravitational wave emission from persistent systems may be detected by ground based interferometers. Finally we re-asses the idea that gravitational wave emission may be balancing the accretion torque in these systems, and show that in most cases the disc/magnetosphere interaction can account for the observed spin periods.

Brynmor Haskell; Nils Andersson; Caroline D`Angelo; Nathalie Degenaar; Kostas Glampedakis; Wynn C. G. Ho; Paul D. Lasky; Andrew Melatos; Manuel Oppenoorth; Alessandro Patruno; Maxim Priymak

2014-07-31T23:59:59.000Z

333

Geodesic-invariant equations of gravitation  

E-Print Network [OSTI]

Einstein's equations of gravitation are not invariant under geodesic mappings, i. e. under a certain class of mappings of the Christoffel symbols and the metric tensor which leave the geodesic equations in a given coordinate system invariant. A theory in which geodesic mappings play the role of gauge transformations is considered.

Leonid V. Verozub

2008-02-04T23:59:59.000Z

334

Interaction of Gravitational Waves with Charged Particles  

E-Print Network [OSTI]

It is shown here that a cloud of charged particles could in principle absorb energy from gravitational waves (GWs) incident upon it, resulting in wave attenuation. This could in turn have implications for the interpretation of future data from early universe GWs.

Wickramasinghe, Thulsi; Revalski, Mitchell

2015-01-01T23:59:59.000Z

335

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

336

On the Vacuum Propagation of Gravitational Waves  

E-Print Network [OSTI]

We show that, for any local, causal quantum field theory which couples covariantly to gravity, and which admits Minkowski spacetime vacuum(a) invariant under the inhomogeneous proper orthochronous Lorentz group, plane gravitational waves propagating in such Minkowski vacuum(a) do not dissipate energy or momentum via quantum field theoretic effects.

Xiao Liu

2007-06-05T23:59:59.000Z

337

General models of Einstein gravity with a non-Newtonian weak-field limit  

E-Print Network [OSTI]

We investigate Einstein theories of gravity, coupled to a scalar field \\vphi and point-like matter, which are characterized by a scalar field-dependent matter coupling function e^{H(\\vphi)}. We show that under mild constraints on the form of the potential for the scalar field, there are a broad class of Einstein-like gravity models -characterized by the asymptotic behavior of H- which allow for a non-Newtonian weak-field limit with the gravitational potential behaving for large distances as ln r. The Newtonian term GM/r appears only as sub-leading. We point out that this behavior is also shared by gravity models described by f(R) Lagrangians. The relevance of our results for the building of infrared modified theories of gravity and for modified Newtonian dynamics is also discussed.

M. Cadoni; M. Casula

2009-01-08T23:59:59.000Z

338

Dark matter: Geometric Gravitation Theorem W.Westenberger SUMMARY Geometric Gravitation Theorem:  

E-Print Network [OSTI]

The centre of gravitational force of masses surrounding symmetrically a geometric centre Z affects a nearby object at a position A as though all masses were concentrated at a point o u t s i d e of the centre Z. There is a circle of radius R around a centre Z. The downside point of this circle may be called A. Using Newton's gravitation law we are searching for the single effective point that affects object A gravitationally as though all of the objects of the volume of radius R were concentrated at this point. Mass divided by square of distance serves as a basis for all calculations. We define a geometric gravitation unit: 1 GGE = the gravitational force of one mass unit at a distance of R First we regard any two gravitational points at the straight line AZ that are symmetrical to Z and we establish that the distance of the single effective point r(W) of these two masses on behalf

unknown authors

339

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

2003-07-01T23:59:59.000Z

340

Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors  

E-Print Network [OSTI]

Gravitational waves deliver information in exquisite detail about astrophysical phenomena, among them the collision of two black holes, a system completely invisible to the eyes of electromagnetic telescopes. Models that predict gravitational wave signals from likely sources are crucial for the success of this endeavor. Modeling binary black hole sources of gravitational radiation requires solving the Eintein equations of General Relativity using powerful computer hardware and sophisticated numerical algorithms. This proceeding presents where we are in understanding ground-based gravitational waves resulting from the merger of black holes and the implications of these sources for the advent of gravitational-wave astronomy.

Shoemaker, Deirdre; London, Lionel; Pekowsky, Larne

2015-01-01T23:59:59.000Z

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.


341

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

342

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.

343

Optical limiting and thermal lensing studies in C60 S. S. Harilal,a)  

E-Print Network [OSTI]

Optical limiting and thermal lensing studies in C60 S. S. Harilal,a) C. V. Bindhu, V. P. N 1999 Optical limiting and thermo-optic properties of C60 in toluene are studied using 532 nm, 9 ns pulses from a frequency-doubled Nd:YAG laser. Optical limiting studies in these fullerene molecules lead

Harilal, S. S.

344

1 Microscopic and environmental controls on the spacing and thickness of segregated 2 ice lenses  

E-Print Network [OSTI]

water, and ice conspire with the prevailing environmental conditions 52 to produce macroscopic ice by Henry (2000). The first comprehensive and tractable model 57 for ice lens growth was produced by O1 Microscopic and environmental controls on the spacing and thickness of segregated 2 ice lenses 3

Rempel, Alan W.

345

Generalized dynamical entropies in weakly chaotic systems  

E-Print Network [OSTI]

A large class of technically non-chaotic systems, involving scatterings of light particles by flat surfaces with sharp boundaries, is nonetheless characterized by complex random looking motion in phase space. For these systems one may define a generalized, Tsallis type dynamical entropy that increases linearly with time. It characterizes a maximal gain of information about the system that increases as a power of time. However, this entropy cannot be chosen independently from the choice of coarse graining lengths and it assigns positive dynamical entropies also to fully integrable systems. By considering these dependencies in detail one usually will be able to distinguish weakly chaotic from fully integrable systems.

Henk van Beijeren

2003-04-28T23:59:59.000Z

346

Weak energy condition violation and superluminal travel  

E-Print Network [OSTI]

Recent solutions to the Einstein Field Equations involving negative energy densities, i.e., matter violating the weak-energy-condition, have been obtained, namely traversable wormholes, the Alcubierre warp drive and the Krasnikov tube. These solutions are related to superluminal travel, although locally the speed of light is not surpassed. It is difficult to define faster-than-light travel in generic space-times, and one can construct metrics which apparently allow superluminal travel, but are in fact flat Minkowski space-times. Therefore, to avoid these difficulties it is important to provide an appropriate definition of superluminal travel.

Francisco Lobo; Paulo Crawford

2002-04-09T23:59:59.000Z

347

Wave turbulent statistics in non-weak wave turbulence  

E-Print Network [OSTI]

In wave turbulence, it has been believed that statistical properties are well described by the weak turbulence theory, in which nonlinear interactions among wavenumbers are assumed to be small. In the weak turbulence theory, separation of linear and nonlinear time scales derived from the weak nonlinearity is also assumed. However, the separation of the time scales is often violated even in weak turbulent systems where the nonlinear interactions are actually weak. To get rid of this inconsistency, closed equations are derived without assuming the separation of the time scales in accordance with Direct-Interaction Approximation (DIA), which has been successfully applied to Navier--Stokes turbulence. The kinetic equation of the weak turbulence theory is recovered from the DIA equations if the weak nonlinearity is assumed as an additional assumption. It suggests that the DIA equations is a natural extension of the conventional kinetic equation to not-necessarily-weak wave turbulence.

Naoto Yokoyama

2011-05-08T23:59:59.000Z

348

Possible violation of Newtonian gravitational law at small distances and constraints on it from the Casimir effect  

E-Print Network [OSTI]

The recent ideas that the gravitational and gauge interactions become united at the weak scale lead to Yukawa-type corrections to the Newtonian gravitational law at small distances. We briefly summarize the best constraints on these corrections obtained recently from the experiments on the measurement of the Casimir force. The new constraints on the Yukawa-type interaction are derived from the latest Casimir force measurement between a large gold coated sphere and flat disk using an atomic force microscope. The obtained constraints are stronger up to 19 times comparing the previous experiment with aluminum surfaces and up to 4500 times comparing the Casimir force measurements between dielectrics. The application range of constraints obtained by means of an atomic force microscope is extended.

V. M. Mostepanenko; M. Novello

2000-08-03T23:59:59.000Z

349

Quantum weak chaos in a degenerate system  

E-Print Network [OSTI]

Quantum weak chaos is studied in a perturbed degenerate system --- a charged particle interacting with a monochromatic wave in a transverse magnetic field. The evolution operator for an arbitrary number of periods of the external field is built and its structure is explored in terms of the QE (quasienergy eigenstates) under resonance condition (wave frequency $=$ cyclotron frequency) in the regime of weak classical chaos. The new phenomenon of diffusion via the quantum separatrices and the influence of chaos on diffusion are investigated and, in the quasi classical limit, compared with its classical dynamics. We determine the crossover from purely quantum diffusion to a diffusion which is the quantum manifestation of classical diffusion along the stochastic web. This crossover results from the non-monotonic dependence of the characteristic localization length of the QE states on the wave amplitude. The width of the quantum separatrices was computed and compared with the width of the classical stochastic web. We give the physical parameters which can be realized experimentally to show the manifestation of quantum chaos in nonlinear acoustic resonance.

V. Ya. Demikhovskii; D. I. Kamenev; G. A. Luna-Acosta

1998-09-27T23:59:59.000Z

350

Simulating weak localization using superconducting quantum circuits  

E-Print Network [OSTI]

Understanding complex quantum matter presents a central challenge in condensed matter physics. The difficulty lies in the exponential scaling of the Hilbert space with the system size, making solutions intractable for both analytical and conventional numerical methods. As originally envisioned by Richard Feynman, this class of problems can be tackled using controllable quantum simulators. Despite many efforts, building an quantum emulator capable of solving generic quantum problems remains an outstanding challenge, as this involves controlling a large number of quantum elements. Here, employing a multi-element superconducting quantum circuit and manipulating a single microwave photon, we demonstrate that we can simulate the weak localization phenomenon observed in mesoscopic systems. By engineering the control sequence in our emulator circuit, we are also able to reproduce the well-known temperature dependence of weak localization. Furthermore, we can use our circuit to continuously tune the level of disorder, a parameter that is not readily accessible in mesoscopic systems. By demonstrating a high level of control and complexity, our experiment shows the potential for superconducting quantum circuits to realize scalable quantum simulators.

Yu Chen; P. Roushan; D. Sank; C. Neill; Erik Lucero; Matteo Mariantoni; R. Barends; B. Chiaro; J. Kelly; A. Megrant; J. Y. Mutus; P. J. J. O'Malley; A. Vainsencher; J. Wenner; T. C. White; Yi Yin; A. N. Cleland; John M. Martinis

2014-03-26T23:59:59.000Z

351

Weak Scale From the Maximum Entropy Principle  

E-Print Network [OSTI]

The theory of multiverse and wormholes suggests that the parameters of the Standard Model are fixed in such a way that the radiation of the $S^{3}$ universe at the final stage $S_{rad}$ becomes maximum, which we call the maximum entropy principle. Although it is difficult to confirm this principle generally, for a few parameters of the Standard Model, we can check whether $S_{rad}$ actually becomes maximum at the observed values. In this paper, we regard $S_{rad}$ at the final stage as a function of the weak scale ( the Higgs expectation value ) $v_{h}$, and show that it becomes maximum around $v_{h}={\\cal{O}}(300\\text{GeV})$ when the dimensionless couplings in the Standard Model, that is, the Higgs self coupling, the gauge couplings, and the Yukawa couplings are fixed. Roughly speaking, we find that the weak scale is given by \\begin{equation} v_{h}\\sim\\frac{T_{BBN}^{2}}{M_{pl}y_{e}^{5}},\

Yuta Hamada; Hikaru Kawai; Kiyoharu Kawana

2014-09-23T23:59:59.000Z

352

Weak Scale From the Maximum Entropy Principle  

E-Print Network [OSTI]

The theory of multiverse and wormholes suggests that the parameters of the Standard Model are fixed in such a way that the radiation of the $S^{3}$ universe at the final stage $S_{rad}$ becomes maximum, which we call the maximum entropy principle. Although it is difficult to confirm this principle generally, for a few parameters of the Standard Model, we can check whether $S_{rad}$ actually becomes maximum at the observed values. In this paper, we regard $S_{rad}$ at the final stage as a function of the weak scale ( the Higgs expectation value ) $v_{h}$, and show that it becomes maximum around $v_{h}={\\cal{O}}(300\\text{GeV})$ when the dimensionless couplings in the Standard Model, that is, the Higgs self coupling, the gauge couplings, and the Yukawa couplings are fixed. Roughly speaking, we find that the weak scale is given by \\begin{equation} v_{h}\\sim\\frac{T_{BBN}^{2}}{M_{pl}y_{e}^{5}},\

Hamada, Yuta; Kawana, Kiyoharu

2014-01-01T23:59:59.000Z

353

Gravitational instability of slowly rotating isothermal spheres  

E-Print Network [OSTI]

We discuss the statistical mechanics of rotating self-gravitating systems by allowing properly for the conservation of angular momentum. We study analytically the case of slowly rotating isothermal spheres by expanding the solutions of the Boltzmann-Poisson equation in a series of Legendre polynomials, adapting the procedure introduced by Chandrasekhar (1933) for distorted polytropes. We show how the classical spiral of Lynden-Bell & Wood (1967) in the temperature-energy plane is deformed by rotation. We find that gravitational instability occurs sooner in the microcanonical ensemble and later in the canonical ensemble. According to standard turning point arguments, the onset of the collapse coincides with the minimum energy or minimum temperature state in the series of equilibria. Interestingly, it happens to be close to the point of maximum flattening. We determine analytically the generalization of the singular isothermal solution to the case of a slowly rotating configuration. We also consider slowly ...

Chavanis, P H

2002-01-01T23:59:59.000Z

354

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

355

Gravitational radiation from preheating with many fields  

SciTech Connect (OSTI)

Parametric resonances provide a mechanism by which particles can be created just after inflation. Thus far, attention has focused on a single or many inflaton fields coupled to a single scalar field. However, generically we expect the inflaton to couple to many other relativistic degrees of freedom present in the early universe. Using simulations in an expanding Friedmann-Lemaître-Robertson-Walker spacetime, in this paper we show how preheating is affected by the addition of multiple fields coupled to the inflaton. We focus our attention on gravitational wave production — an important potential observational signature of the preheating stage. We find that preheating and its gravitational wave signature is robust to the coupling of the inflaton to more matter fields.

Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier, E-mail: giblinj@kenyon.edu, E-mail: larry@gravity.phys.uwm.edu, E-mail: siemens@gravity.phys.uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin — Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)

2010-08-01T23:59:59.000Z

356

Gravitational Waves in Ghost Free Bimetric Gravity  

E-Print Network [OSTI]

We obtain a set of exact gravitational wave solutions for the ghost free bimetric theory of gravity. With a flat reference metric, the theory admits the vacuum Brinkmann plane wave solution for suitable choices of the coefficients of different terms in the interaction potential. An exact gravitational wave solution corresponding to a massive scalar mode is also admitted for arbitrary choice of the coefficients with the reference metric being proportional to the spacetime metric. The proportionality factor and the speed of the wave are calculated in terms of the parameters of the theory. We also show that a F(R) extension of the theory admits similar solutions but in general is plagued with ghost instabilities.

Morteza Mohseni

2012-11-15T23:59:59.000Z

357

A Connection between Gravitation and Electromagnetism  

E-Print Network [OSTI]

It is argued that there is a connection between the fundamental forces of electromagnetism and gravitation. This connection occurs because of: 1) the fundamental significance of the finite and invariant velocity of light in inertial reference frames in the special theory, and 2) the reliance of the general theory of relativity upon the special theory of relativity locally in spacetime. The connection between the fundamental forces of electromagnetism and gravitation follows immediately from these two points. A brief review is provided of: 1) the role of the finite and invariant velocity of light in inertial reference frames in the special theory, and 2) certain fundamental concepts of the general theory, including its reliance on the special theory locally.

D. M. Snyder

2000-02-16T23:59:59.000Z

358

Some Wave Equations for Electromagnetism and Gravitation  

E-Print Network [OSTI]

The paper studies the inferences of wave equations for electromagnetic fields when there are gravitational fields at the same time. In the description with the algebra of octonions, the inferences of wave equations are identical with that in conventional electromagnetic theory with vector terminology. By means of the octonion exponential function, we can draw out that the electromagnetic waves are transverse waves in a vacuum, and rephrase the law of reflection, Snell's law, Fresnel formula, and total internal reflection etc. The study claims that the theoretical results of wave equations for electromagnetic strength keep unchanged in the case for coexistence of gravitational and electromagnetic fields. Meanwhile the electric and magnetic components of electromagnetic waves can not be determined simultaneously in electromagnetic fields.

Zi-Hua Weng

2010-08-11T23:59:59.000Z

359

Nuclear and gravitational energies in stars  

E-Print Network [OSTI]

The force that governs the evolution of stars is gravity. Indeed this force drives star formation, imposes thermal and density gradients into stars at hydrostatic equilibrium and finally plays the key role in the last phases of their evolution. Nuclear power in stars governs their lifetimes and of course the stellar nucleosynthesis. The nuclear reactions are at the heart of the changes of composition of the baryonic matter in the Universe. This change of composition, in its turn, has profound consequences on the evolution of stars and galaxies. The energy extracted from the gravitational, respectively nuclear reservoirs during the lifetimes of stars of different masses are estimated. It is shown that low and intermediate mass stars (M 8 Msol), which explode in a supernova explosion, extract more than 5 times more energy from the gravitational reservoir than from the nuclear one. We conclude by discussing a few important nuclear reactions and their link to topical astrophysical questions.

Meynet, Georges; Ekström, Sylvia

2013-01-01T23:59:59.000Z

360

SNAP Telescope Performance for Weak Lensing Surveys M.Lampton1, M.Sholl1, P.Jelinsky1, and H.Stabenau2 for the SNAP Collaboration  

E-Print Network [OSTI]

.7 µm * 0.7 deg2 instantaneous pixellized field * 70 deg solar avoidance angle Telescope basics Annular of Energy, through contract DE-AC02-05CH11231. Expect extreme PSF Stability * telescope is thermally isolated from outer baffle * no deployed panels, antennas, or radiators * active thermal control on optics

California at Berkeley, University of

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.


361

CVS $Revision: 2.0 $Date: 2002/10/10 15:47:21 Weak Lensing Results from the 75 Square Degree CTIO Survey  

E-Print Network [OSTI]

Survey M. Jarvis 1;2 , G. M. Bernstein 1;2 , P. Fischer 1;3 , D. Smith 1;4 Department of Astronomy to have #27; 8( m =0:3) 0:57 = 0:71 +0:12 0:16 (95% CL, #3;CDM, = 0:21), where the systematic error of matter uctuations in the Universe (Valdes, Tyson, & Jarvis 1983; Miralda-Escud#19;e 1991; Kaiser 1992

Bernstein, Gary

362

Energy-momentum Density of Gravitational Waves  

E-Print Network [OSTI]

In this paper, we elaborate the problem of energy-momentum in general relativity by energy-momentum prescriptions theory. Our aim is to calculate energy and momentum densities for the general form of gravitational waves. In this connection, we have extended the previous works by using the prescriptions of Bergmann and Tolman. It is shown that they are finite and reasonable. In addition, using Tolman prescription, exactly, leads to same results that have been obtained by Einstein and Papapetrou prescriptions.

Amir M. Abbassi; Saeed Mirshekari

2014-11-29T23:59:59.000Z

363

Non-expanding impulsive gravitational waves  

E-Print Network [OSTI]

We investigate a class of impulsive gravitational waves which propagate either in Minkowski or in the (anti-)de Sitter background. These waves are constructed as impulsive members of the Kundt class $P(\\Lambda)$ of non-twisting, non-expanding type N solutions of vacuum Einstein equations with a cosmological constant $\\Lambda$. We show that the only non-trivial waves of this type in Minkowski spacetime are impulsive pp-waves. For $\\Lambda\

J. Podolsky

1998-07-29T23:59:59.000Z

364

On Principle of Universality of Gravitational Interactions  

E-Print Network [OSTI]

In this work, the experiment is discussed on the verification of the principle of universality of gravitational interactions and some related problems of gravity theory and physics of elementary particles. The meaning of this proposal lies in the fact that the self-consistency of General Relativity, as it turns out, presuppose the existence of the nongravitating form of energy. Theory predicts that electrons are particles that transfer the nongravitating form of energy.

I. B. Pestov

2001-12-19T23:59:59.000Z

365

Gravitation: in search of the missing torsion  

E-Print Network [OSTI]

A linear Lorentz connection has always two fundamental derived characteristics: curvature and torsion. The latter is assumed to vanish in general relativity. Three gravitational models involving non-vanishing torsion are examined: teleparallel gravity, Einstein-Cartan, and new general relativity. Their dependability is critically examined. Although a final answer can only be given by experience, it is argued that teleparallel gravity provides the most consistent approach.

R. Aldrovandi; J. G. Pereira

2008-01-27T23:59:59.000Z

366

LIGO and the Search for Gravitational Waves  

SciTech Connect (OSTI)

Gravitational waves, predicted to exist by Einstein's General Theory of Relativity but as yet undetected, are expected to be emitted during violent astrophysical events such as supernovae, black hole interactions and the coalescence of compact binary systems. Their detection and study should lead to a new branch of astronomy. However the experimental challenge is formidable: ground-based detection relies on sensing displacements of order 10{sup -18} m over a frequency range of tens of hertz to a few kHz. There is currently a large international effort to commission and operate long baseline interferometric detectors including those that comprise LIGO - the Laser Interferometer Gravitational-Wave Observatory - in the USA. In this talk I will give an introduction to the topic of gravitational wave detection and in particular review the status of the LIGO project which is currently taking data at its design sensitivity. I will also look to the future to consider planned improvements in sensitivity for such detectors, focusing on Advanced LIGO, the proposed upgrade to the LIGO project.

Robertson, Norna A.

2006-10-16T23:59:59.000Z

367

Gravitational instability of slowly rotating isothermal spheres  

E-Print Network [OSTI]

We discuss the statistical mechanics of rotating self-gravitating systems by allowing properly for the conservation of angular momentum. We study analytically the case of slowly rotating isothermal spheres by expanding the solutions of the Boltzmann-Poisson equation in a series of Legendre polynomials, adapting the procedure introduced by Chandrasekhar (1933) for distorted polytropes. We show how the classical spiral of Lynden-Bell & Wood (1967) in the temperature-energy plane is deformed by rotation. We find that gravitational instability occurs sooner in the microcanonical ensemble and later in the canonical ensemble. According to standard turning point arguments, the onset of the collapse coincides with the minimum energy or minimum temperature state in the series of equilibria. Interestingly, it happens to be close to the point of maximum flattening. We determine analytically the generalization of the singular isothermal solution to the case of a slowly rotating configuration. We also consider slowly rotating configurations of the self-gravitating Fermi gas at non zero temperature.

P. -H. Chavanis

2002-04-14T23:59:59.000Z

368

Nuclear and gravitational energies in stars  

SciTech Connect (OSTI)

The force that governs the evolution of stars is gravity. Indeed this force drives star formation, imposes thermal and density gradients into stars at hydrostatic equilibrium and finally plays the key role in the last phases of their evolution. Nuclear power in stars governs their lifetimes and of course the stellar nucleosynthesis. The nuclear reactions are at the heart of the changes of composition of the baryonic matter in the Universe. This change of composition, in its turn, has profound consequences on the evolution of stars and galaxies. The energy extracted from the gravitational, respectively nuclear reservoirs during the lifetimes of stars of different masses are estimated. It is shown that low and intermediate mass stars (M < 8 M{sub ?}) extract roughly 90 times more energy from their nuclear reservoir than from their gravitational one, while massive stars (M > 8 M{sub ?}), which explode in a supernova explosion, extract more than 5 times more energy from the gravitational reservoir than from the nuclear one. We conclude by discussing a few important nuclear reactions and their link to topical astrophysical questions.

Meynet, Georges; Ekström, Sylvia [Astronomical Observatory of Geneva University (Switzerland); Courvoisier, Thierry [ISDC, Astronomical Observatory of Geneva University (Switzerland)

2014-05-09T23:59:59.000Z

369

Non-equilibrium thermodynamics of gravitational screens  

E-Print Network [OSTI]

We study the Einstein gravity equations projected on a timelike surface, which represents the time evolution of what we call a gravitational screen. We show that such a screen possesses a surface tension and an internal energy, and that the Einstein equations reduce to the thermodynamic equations of a viscous bubble. We also provide a complete dictionary between gravitational and thermodynamical variables. In the non-viscous cases there are three thermodynamic equations which characterise a bubble dynamics: These are the first law, the Marangoni flow equation and the Young-Laplace equation. In all three equations the surface tension plays a central role: In the first law it appears as a work term per unit area, in the Marangoni flow its gradient drives a force, and in the Young-Laplace equation it contributes to a pressure proportional to the surface curvature. The gravity equations appear as a natural generalization of these bubble equations when the bubble itself is viscous and dynamical. In particular, it shows that the mechanism of entropy production for the viscous bubble is mapped onto the production of gravitational waves. We also review the relationship between surface tension and temperature, and discuss the usual black-hole thermodynamics from this point of view.

Laurent Freidel; Yuki Yokokura

2014-05-19T23:59:59.000Z

370

GRAVITATIONAL FIELD SHIELDING AND SUPERNOVA EXPLOSIONS  

SciTech Connect (OSTI)

A new mechanism for supernova explosions called gravitational field shielding is proposed, in accord with a five-dimensional fully covariant Kaluza-Klein theory with a scalar field that unifies the four-dimensional Einsteinian general relativity and Maxwellian electromagnetic theory. It is shown that a dense compact collapsing core of a star will suddenly turn off or completely shield its gravitational field when the core collapses to a critical density, which is inversely proportional to the square of mass of the core. As the core suddenly turns off its gravity, the extremely large pressure immediately stops the core collapse and pushes the mantle material of supernova moving outward. The work done by the pressure in the expansion can be the order of energy released in a supernova explosion. The gravity will resume and stop the core from a further expansion when the core density becomes less than the critical density. Therefore, the gravitational field shielding leads a supernova to impulsively explode and form a compact object such as a neutron star as a remnant. It works such that a compressed spring will shoot the oscillator out when the compressed force is suddenly removed.

Zhang, T. X. [Physics Department, Alabama A and M University, Normal, AL 35762 (United States)

2010-12-20T23:59:59.000Z

371

Gravitational dynamics in Bose Einstein condensates  

E-Print Network [OSTI]

Analogue models for gravity intend to provide a framework where matter and gravity, as well as their intertwined dynamics, emerge from degrees of freedom that have a priori nothing to do with what we call gravity or matter. Bose Einstein condensates (BEC) are a natural example of analogue model since one can identify matter propagating on a (pseudo-Riemannian) metric with collective excitations above the condensate of atoms. However, until now, a description of the "analogue gravitational dynamics" for such model was missing. We show here that in a BEC system with massive quasi-particles, the gravitational dynamics can be encoded in a modified (semi-classical) Poisson equation. In particular, gravity is of extreme short range (characterized by the healing length) and the cosmological constant appears from the non-condensed fraction of atoms in the quasi-particle vacuum. While some of these features make the analogue gravitational dynamics of our BEC system quite different from standard Newtonian gravity, we nonetheless show that it can be used to draw some interesting lessons about "emergent gravity" scenarios.

Florian Girelli; Stefano Liberati; Lorenzo Sindoni

2008-12-03T23:59:59.000Z

372

The MOG Weak Field approximation II. Observational test of Chandra X-ray Clusters  

E-Print Network [OSTI]

We apply the weak field approximation limit of the covariant Scalar-Tensor-Vector Gravity (STVG) theory, so-called MOdified gravity (MOG), to the dynamics of clusters of galaxies by using only baryonic matter. The MOG effective gravitational potential in the weak field approximation is composed of an attractive Newtonian term and a repulsive Yukawa term with two parameters $\\alpha$ and $\\mu$. The numerical values of these parameters have been obtained by fitting the predicted rotation curves of galaxies to observational data, yielding the best fit result: $\\alpha = 8.89 \\pm 0.34$ and $\\mu= 0.042\\pm 0.004$ kpc$^{-1}$~\\cite{rah13}. We extend the observational test of this theory to clusters of galaxies, using data for the ionized gas and the temperature profile of nearby clusters obtained by the Chandra X-ray telescope. Using the MOG virial theorem for clusters, we compare the mass profiles of clusters from observation and theory for eleven clusters. The theoretical mass profiles for the inner parts of clusters exceed the observational data. However, the observational data for the inner parts of clusters (i.e., $r<0.1 r_{500}$) is scattered, but at distances larger than $\\sim 300$ kpc, the observed and predicted mass profiles converge. Our results indicate that MOG as a theory of modified gravity is compatible with the observational data from the the solar system to Mega parsec scales without invoking dark matter.

J. W. Moffat; S. Rahvar

2014-06-07T23:59:59.000Z

373

Search for periodic gravitational radiation with the ALLEGRO gravitational wave detector  

E-Print Network [OSTI]

We describe the search for a continuous signal of gravitational radiation from a rotating neutron star in the data taken by the ALLEGRO gravitational wave detector in early 1994. Since ALLEGRO is sensitive at frequencies near 1 kHz, only neutron stars with spin periods near 2 ms are potential sources. There are no known sources of this typ e for ALLEGRO, so we directed the search towards both the galactic center and the globular clus ter 47 Tucanae. The analysis puts a constraint of roughly $8 \\times 10^{-24}$ at frequencies near 1 kHz on the gravitational strain emitted from pulsar spin-down in either 47 Tucanae or the galactic center.

E. Mauceli; M. P. McHugh; W. O. Hamilton; W. W. Johnson; A. Morse

2000-07-11T23:59:59.000Z

374

Search for periodic gravitational radiation with the ALLEGRO gravitational wave detector  

E-Print Network [OSTI]

We describe the search for a continuous signal of gravitational radiation from a rotating neutron star in the data taken by the ALLEGRO gravitational wave detector in early 1994. Since ALLEGRO is sensitive at frequencies near 1 kHz, only neutron stars with spin periods near 2 ms are potential sources. There are no known sources of this typ e for ALLEGRO, so we directed the search towards both the galactic center and the globular clus ter 47 Tucanae. The analysis puts a constraint of roughly $8 \\times 10^{-24}$ at frequencies near 1 kHz on the gravitational strain emitted from pulsar spin-down in either 47 Tucanae or the galactic center.

Mauceli, E; Hamilton, W O; Johnson, W W; Morse, A

2002-01-01T23:59:59.000Z

375

Is Fusion Inhibited for Weakly Bound Nuclei?  

SciTech Connect (OSTI)

Complete fusion of light radioactive nuclei is predicted to be hindered at near-barrier energies. This feature is investigated in the case of the least bound stable nuclei. Evaporation residues resulting from the {sup 6,7}Li+{sup 9}Be and {sup 6,7}Li+{sup 12}C fusion reactions have been measured in order to study common features in reactions involving light weakly bound nuclei. The experimental excitation functions revealed that the fusion cross section is significantly smaller than the total reaction cross section and also smaller than the fusion cross section expected from the available systematics. A clear correlation between the fusion probability and nucleon (cluster) separation energy has been established.The results suggest that the breakup process has a strong influence on the hindrance of the fusion cross section. {copyright} {ital 1996} {ital The American Physical Society}

Takahashi, J.; Munhoz, M.; Szanto, E.M.; Carlin, N.; Added, N.; Suaide, A.A.; de Moura, M.M.; Liguori Neto, R.; Szanto de Toledo, A. [Universidade de Sao Paulo, Institute de Fisica, Departamento de Fisica Nuclear, Caixa Postal 66318, 05389-970 Sao Paulo, Sao Paulo, (Brasil)] [Universidade de Sao Paulo, Institute de Fisica, Departamento de Fisica Nuclear, Caixa Postal 66318, 05389-970 Sao Paulo, Sao Paulo, (Brasil); Canto, L.F. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21945-970 Rio de Janeiro, RJ, (Brasil)] [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21945-970 Rio de Janeiro, RJ, (Brasil)

1997-01-01T23:59:59.000Z

376

Weakly nonassociative algebras, Riccati and KP hierarchies  

E-Print Network [OSTI]

It has recently been observed that certain nonassociative algebras (called "weakly nonassociative", WNA) determine, via a universal hierarchy of ordinary differential equations, solutions of the KP hierarchy with dependent variable in an associative subalgebra (the middle nucleus). We recall central results and consider a class of WNA algebras for which the hierarchy of ODEs reduces to a matrix Riccati hierarchy, which can be easily solved. The resulting solutions of a matrix KP hierarchy then determine (under a rank 1 condition) solutions of the scalar KP hierarchy. We extend these results to the discrete KP hierarchy. Moreover, we build a bridge from the WNA framework to the Gelfand-Dickey formulation of the KP hierarchy.

Aristophanes Dimakis; Folkert Muller-Hoissen

2008-01-16T23:59:59.000Z

377

Graphene transparency in weak magnetic fields  

E-Print Network [OSTI]

We carry out an explicit calculation of the vacuum polarization tensor for an effective low-energy model of monolayer graphene in the presence of a weak magnetic field of intensity $B$ perpendicularly aligned to the membrane. By expanding the quasiparticle propagator in the Schwinger proper time representation up to order $(eB)^2$, where $e$ is the unit charge, we find an explicitly transverse tensor, consistent with gauge invariance. Furthermore, assuming that graphene is radiated with monochromatic light of frequency $\\omega$ along the external field direction, from the modified Maxwell's equations we derive the intensity of transmitted light and the angle of polarization rotation in terms of the longitudinal ($\\sigma_{xx}$) and transverse ($\\sigma_{xy}$) conductivities. Corrections to these quantities, both calculated and measured, are of order $(eB)^2/\\omega^4$. Our findings generalize and complement previously known results reported in literature regarding the light absorption problem in graphene from th...

Valenzuela, David; Loewe, Marcelo; Raya, Alfredo

2014-01-01T23:59:59.000Z

378

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 approximate 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 experiments 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.

Habib Ammari; Thomas Boulier; Josselin Garnier

2012-03-05T23:59:59.000Z

379

Bipolar outflows as a repulsive gravitational phenomenon -- Azimuthally Symmetric Theory of Gravitation (II)  

E-Print Network [OSTI]

This paper is part of a series on the Azimuthally Symmetric Theory of Gravitation (ASTG) which is built on Laplace-Poisson's well known equation. We show herein that the emergent equations from the ASTG, under some critical conditions determined by the spin, do possess repulsive gravitational fields in the polar regions of the gravitating body in question. This places the ASTG on an interesting pedestal to infer the origins of outflows as a repulsive gravitational phenomenon. Outflows are a ubiquitous phenomenon found in star forming systems and their true origin is a question yet to be settled. Given the current thinking on their origin, the direction that the present paper takes is nothing short of an asymptotic break from conventional wisdom; at the very least, it is a complete paradigm shift because gravitation is not at all associated with this process, but rather it is thought to be an all-attractive force that only tries to squash matter together onto a single point. Additionally, we show that the emergent Azimuthally Symmetric Gravitational Field from the ASTG strongly suggests a solution to the supposed Radiation Problem that is thought to be faced by massive stars in their process of formation. That is, at about 8-10Msun radiation from the nascent star is expected to halt the accretion of matter. We show that in-falling material will fall onto the equatorial disk and from there, this material will be channeled onto the forming star via the equatorial plane, thus accretion of mass continues well past the value of about 8-10Msun, albeit via the disk. Along the equatorial plane, the net force (with the radiation force included) on any material there-on right up to the surface of the star is directed toward the forming star, hence accretion of mass by the nascent star is un-hampered.

G. G. Nyambuya

2010-10-18T23:59:59.000Z

380

Characterising the Gravitational Instability in Cooling Accretion Discs  

E-Print Network [OSTI]

We perform numerical analyses of the structure induced by gravitational instabilities in cooling gaseous accretion discs. For low enough cooling rates a quasi-steady configuration is reached, with the instability saturating at a finite amplitude in a marginally stable disc. We find that the saturation amplitude scales with the inverse square root of the cooling parameter beta = t_cool / t_dyn, which indicates that the heating rate induced by the instability is proportional to the energy density of the induced density waves. We find that at saturation the energy dissipated per dynamical time by weak shocks due is of the order of 20 per cent of the wave energy. From Fourier analysis of the disc structure we find that while the azimuthal wavenumber is roughly constant with radius, the mean radial wavenumber increases with radius, with the dominant mode corresponding to the locally most unstable wavelength. We demonstrate that the density waves excited in relatively low mass discs are always close to co-rotation, deviating from it by approximately 10 per cent. This can be understood in terms of the flow Doppler-shifted phase Mach number -- the pattern speed self-adjusts so that the flow into spiral arms is always sonic. This has profound effects on the degree to which transport through self-gravity can be modelled as a viscous process. Our results thus provide (a) a detailed description of how the self-regulation mechanism is established for low cooling rates, (b) a clarification of the conditions required for describing the transport induced by self-gravity through an effective viscosity, (c) an estimate of the maximum amplitude of the density perturbation before fragmentation occurs, and (d) a simple recipe to estimate the density perturbation in different thermal regimes.

Peter Cossins; Giuseppe Lodato; Cathie Clarke

2008-11-21T23:59:59.000Z

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.


381

The Q_weak Experimental Apparatus  

E-Print Network [OSTI]

The Jefferson Lab Q_weak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise ${\\vec{e}}$p asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. The experiment employed 180 microA of 89% longitudinally polarized electrons whose helicity was reversed 960 times per second. The electrons were accelerated to 1.16 GeV and directed to a beamline with extensive instrumentation to measure helicity-correlated beam properties that can induce false asymmetries. Moller and Compton polarimetry were used to measure the electron beam polarization to better than 1%. The electron beam was incident on a 34.4 cm liquid hydrogen target. After passing through a triple collimator system, scattered electrons between 5.8 degrees and 11.6 degrees were bent in the toroidal magnetic field of a resistive copper-coil magnet. The electrons inside this acceptance were focused onto eight fused silica Cerenkov detectors arrayed symmetrically around the beam axis. A total scattered electron rate of about 7 GHz was incident on the detector array. The detectors were read out in integrating mode by custom-built low-noise pre-amplifiers and 18-bit sampling ADC modules. The momentum transfer Q^2 = 0.025 GeV^2 was determined using dedicated low-current (~100 pA) measurements with a set of drift chambers before (and a set of drift chambers and trigger scintillation counters after) the toroidal magnet.

Qweak Collaboration; T. Allison; M. Anderson; D. Androic; D. S. Armstrong; A. Asaturyan; T. D. Averett; R. Averill; J. Balewski; J. Beaufait; R. S. Beminiwattha; J. Benesch; F. Benmokhtar; J. Bessuille; J. Birchall; E. Bonnell; J. Bowman; P. Brindza; D. B. Brown; R. D. Carlini; G. D. Cates; B. Cavness; G. Clark; J. C. Cornejo; S. Covrig Dusa; M. M. Dalton; C. A. Davis; D. C. Dean; W. Deconinck; J. Diefenbach; K. Dow; J. F. Dowd; J. A. Dunne; D. Dutta; W. S. Duvall; J. R. Echols; M. Elaasar; W. R. Falk; K. D. Finelli; J. M. Finn; D. Gaskell; M. T. W. Gericke; J. Grames; V. M. Gray; K. Grimm; F. Guo; J. Hansknecht; D. J. Harrison; E. Henderson; J. R. Hoskins; E. Ihloff; K. Johnston; D. Jones; M. Jones; R. Jones; M. Kargiantoulakis; J. Kelsey; N. Khan; P. M. King; E. Korkmaz; S. Kowalski; A. Kubera; J. Leacock; J. P. Leckey; A. R. Lee; J. H. Lee; L. Lee; Y. Liang; S. MacEwan; D. Mack; J. A. Magee; R. Mahurin; J. Mammei; J. W. Martin; A. McCreary; M. H. McDonald; M. J. McHugh; P. Medeiros; D. Meekins; J. Mei; R. Michaels; A. Micherdzinska; A. Mkrtchyan; H. Mkrtchyan; N. Morgan; J. Musson; K. E. Mesick; 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; W. R. Roberts; J. Roche; P. W. Rose; B. Sawatzky; T. Seva; M. H. Shabestari; R. Silwal; N. Simicevic; G. R. Smith; S. Sobczynski; P. Solvignon; D. T. Spayde; B. Stokes; D. W. Storey; A. Subedi; R. Subedi; R. Suleiman; V. Tadevosyan; W. A. Tobias; V. Tvaskis; E. Urban; B. Waidyawansa; P. Wang; S. P. Wells; S. A. Wood; S. Yang; S. Zhamkochyan; R. B. Zielinski

2015-01-06T23:59:59.000Z

382

SEARCHING FOR COOLING SIGNATURES IN STRONG LENSING GALAXY CLUSTERS: EVIDENCE AGAINST BARYONS SHAPING THE MATTER DISTRIBUTION IN CLUSTER CORES  

E-Print Network [OSTI]

The process by which the mass density profile of certain galaxy clusters becomes centrally concentrated enough to produce high strong lensing (SL) cross-sections is not well understood. It has been suggested that the ...

Blanchard, Peter K.

383

Dynamics of a self-gravitating thin string in scalar-tensor theories of gravitation  

E-Print Network [OSTI]

We examine the dynamics of a self-gravitating string in the scalar-tensor theories of gravitation by considering a thin tube of matter to describe it. For a class of solutions, we obtain in the generic case that the extrinsic curvature of the world sheet of the central line is null in the limit where the radius of the string tends to zero. However, if we impose a specific constraint on the behaviour of the solution then we find that only the mean curvature of the world sheet of the central line vanishes which is just the Nambu-Goto dynamics. This analysis can include the massless dilatonic theories of gravity.

B. Boisseau; B. Linet

1997-06-09T23:59:59.000Z

384

Gravitational waves from a curvaton model with blue spectrum  

SciTech Connect (OSTI)

We investigate the gravitational wave background induced by the first order scalar perturbations in the curvaton models. We consider the quadratic and axion-like curvaton potential which can generate the blue-tilted power spectrum of curvature perturbations on small scales and derive the maximal amount of gravitational wave background today. We find the power spectrum of the induced gravitational wave background has a characteristic peak at the frequency corresponding to the scale reentering the horizon at the curvaton decay, in the case where the curvaton does not dominate the energy density of the Universe. We also find the enhancement of the amount of the gravitational waves in the case where the curvaton dominates the energy density of the Universe. Such induced gravitational waves would be detectable by the future space-based gravitational wave detectors or pulsar timing observations.

Kawasaki, Masahiro; Kitajima, Naoya; Yokoyama, Shuichiro, E-mail: kawasaki@icrr.u-tokyo.ac.jp, E-mail: nk610@icrr.u-tokyo.ac.jp, E-mail: shu@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan)

2013-08-01T23:59:59.000Z

385

Universal Gravitational Constant EX-9908 Page 1 of 13 Re-Written by Geoffrey R. Clarion  

E-Print Network [OSTI]

Newton was able to deduce his law of universal gravitation. Newton's law of universal gravitation: 2 21 rUniversal Gravitational Constant EX-9908 Page 1 of 13 Re-Written by Geoffrey R. Clarion Universal Gravitational Constant EQUIPMENT 1 Gravitational Torsion Balance AP-8215 1 X-Y Adjustable Diode Laser OS-8526A 1

Dai, Pengcheng

386

Gravitational waves from BBH-systems? A (doubly) vain quest  

E-Print Network [OSTI]

The theoretical reasons at the root of LIGO's experimental failure in searching gravitational waves (GW's) from binary black hole (BBH) inspirals.

A. Loinger

2006-02-06T23:59:59.000Z

387

Mapping the nano-Hertz gravitational wave sky  

E-Print Network [OSTI]

We describe a new method for extracting gravitational wave signals from pulsar timing data. We show that any gravitational wave signal can be decomposed into an orthogonal set of sky maps, with the number of maps equal to the number of pulsars in the timing array. These maps may be used as a basis to construct gravitational wave templates for any type of source, including collections of point sources. A variant of the standard Hellings-Downs correlation analysis is recovered for statistically isotropic signals. The template based approach allows us to probe potential anisotropies in the signal and produce maps of the gravitational wave sky.

Neil J. Cornish; Rutger van Haasteren

2014-06-19T23:59:59.000Z

388

THE STRUCTURE OF THE X-RAY AND OPTICAL EMITTING REGIONS OF THE LENSED QUASAR Q 2237+0305  

SciTech Connect (OSTI)

We use gravitational microlensing to determine the size of the X-ray and optical emission regions of the quadruple lens system Q 2237+0305. The optical half-light radius, log(R{sub 1/2,V}/cm) = 16.41 {+-} 0.18 (at {lambda}{sub rest} = 2018 A), is significantly larger than the observed soft, log(R{sub 1/2,soft}/cm)=15.76{sup +0.41}{sub -0.34} (1.1-3.5 keV in the rest frame), and hard, log(R{sub 1/2,hard}/cm)=15.46{sup +0.34}{sub -0.29} (3.5-21.5 keV in the rest frame), band X-ray emission. There is weak evidence that the hard component is more compact than the soft, with log(R{sub 1/2,soft}/R{sub 1/2,hard}){approx_equal}0.30{sup +0.53}{sub -0.45}. This wavelength-dependent structure agrees with recent results found in other lens systems using microlensing techniques, and favors geometries in which the corona is concentrated near the inner edge of the accretion disk. While the available measurements are limited, the size of the X-ray emission region appears to be roughly proportional to the mass of the central black hole.

Mosquera, A. M.; Kochanek, C. S.; Blackburne, J. A. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Chen, B.; Dai, X. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Chartas, G. [Department of Physics and Astronomy, College of Charleston, Charleston, SC 29424 (United States)

2013-05-20T23:59:59.000Z

389

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

390

Optics elements for modeling electrostatic lenses and accelerator components II. Acceleration columns  

SciTech Connect (OSTI)

A set of optical models for a variety of electrostatic lenses and accelerator columns has been developed for the computer code TRACE 3-D. TRACE 3-D is an envelope (matrix) code including space charge that is often used to model bunched beams in magnetic transport systems and radiofrequency (RF) accelerators when the effects of beam current may be important. Several new matrix models have been developed that allow the code to be used for modeling beam lines and accelerators with electrostatic components. The new models include a number of options for: (1) einzel lenses, (2) accelerator columns, (3) electrostatic deflectors (prisms), and (4) an electrostatic quadrupole. A prescription for setting up the initial beam appropriate to modeling 2-D (continuous) beams has also been developed. The new models for (2) are described in this paper, selected comparisons with other calculations are presented, and a beamline application is summarized.

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

1998-05-01T23:59:59.000Z

391

The Emission of Electromagnetic Radiation from Charges Accelerated by Gravitational Waves and its Astrophysical Implications  

E-Print Network [OSTI]

We provide calculations and theoretical arguments supporting the emission of electromagnetic radiation from charged particles accelerated by gravitational waves (GWs). These waves have significant indirect evidence to support their existence, yet they interact weakly with ordinary matter. We show that the induced oscillations of charged particles interacting with a GW, which lead to the emission of electromagnetic radiation, will also result in wave attenuation. These ideas are supported by a small body of literature, as well as additional arguments for particle acceleration based on GW memory effects. We derive order of magnitude power calculations for various initial charge distributions accelerated by GWs. The resulting power emission is extremely small for all but very strong GWs interacting with large quantities of charge. If the results here are confirmed and supplemented, significant consequences such as attenuation of early universe GWs could result. Additionally, this effect could extend GW detection...

Revalski, Mitchell; Wickramasinghe, Thulsi

2015-01-01T23:59:59.000Z

392

Constraints on Light Pseudoscalars Implied by Tests of the Gravitational Inverse-Square Law  

E-Print Network [OSTI]

The exchange of light pseudoscalars between fermions leads to a spin-independent potential in order g^4, where g is the Yukawa pseudoscalar-fermion coupling constant. This potential gives rise to detectable violations of both the weak equivalence principle (WEP) and the gravitational inverse-square law (ISL), even if g is quite small. We show that when previously derived WEP constraints are combined with those arisingfrom ISL tests, a direct experimental limit on the Yukawa coupling of light pseudoscalars to neutrons can be inferred for the first time (g_n^2/4pi < 1.6 \\times 10^-7), along with a new (and significantly improved) limit on the coupling of light pseudoscalars to protons.

Ephraim Fischbach; Dennis E. Krause

1999-06-03T23:59:59.000Z

393

A Monitor of the Focusing Strength of Plasma Lenses Using MeV Synchrotron Radiation  

E-Print Network [OSTI]

The focusing strength of plasma lenses used with high energy electron or positron beams can give rise to synchrotron radiation with critical energies in the MeV range. A method is described for measuring the characteristic energy of this radiation as a way of monitoring the strength of the focus. The principle has been implemented in a plasma lens experiment with a 28.5 GeV positron beam.

Clive Field; Gholam Mazaheri; Johnny S. T. Ng

2002-01-17T23:59:59.000Z

394

X-ray and Optical Flux Ratio Anomalies in Quadruply Lensed Quasars  

E-Print Network [OSTI]

X-ray and Optical Flux Ratio Anomalies in Quadruply Lensed Quasars: Zooming in on Quasar Emission T (r) = 3GMBH M 8r3 1/4 1 - r0/r 1/4 2�1015 cm 100 Rg Optical X-ray 0.1 µarcsec 5 narcsec L ~ 1045-ray and optical should be affected the same Differences in X-ray and optical microlensing #12;Chandra 0.5 ­ 8 ke

California at Santa Cruz, University of

395

Multidimensional gravitational model with anisotropic pressure  

E-Print Network [OSTI]

We consider the gravitational model with additional spatial dimensions and anisotropic pressure which is nonzero only in these dimensions. Cosmological solutions in this model include accelerated expansion of the Universe at late age of its evolution and dynamical compactification of extra dimensions. This model describes observational data for Type Ia supernovae on the level or better than the $\\Lambda$CDM model. We analyze two equations of state resulting in different predictions for further evolution, but in both variants the acceleration epoch is finite.

O. A. Grigorieva; G. S. Sharov

2014-02-18T23:59:59.000Z

396

Spinor One-forms as Gravitational Potentials  

E-Print Network [OSTI]

General relativity is derived from an action which is quadratic in the covariant derivative of certain spinor one-form gravitational potentials. Either a pair of 2-component spinor one-forms or a single Dirac spinor one-form can be employed. The metric is a quadratic function of these spinor one-forms. In the 2-component spinor formulation the action differs from the usual chiral action for general relativity by a total differential. In the Dirac spinor formulation the action is the real part of the former one. The Hamiltonian is related to the ones in positive energy proofs and spinorial quasilocal mass constructions.

Roh Suan Tung; Ted Jacobson

1995-02-23T23:59:59.000Z

397

Spherical gravitating condensers in general relativity  

SciTech Connect (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

398

Standing gravitational waves from domain walls  

SciTech Connect (OSTI)

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

399

Stars as resonant absorbers of gravitational waves  

E-Print Network [OSTI]

Quadrupole oscillation modes in stars can resonate with incident gravitational waves (GWs), and grow non-linear at the expense of GW energy. Stars near massive black hole binaries (MBHB) can act as GW-charged batteries, cooling radiatively. Mass-loss from these stars can prompt MBHB accretion at near-Eddington rates. GW opacity is independent of amplitude, so distant resonating stars can eclipse GW sources. Absorption by the Sun of GWs from Galactic white dwarf binaries may be detectable with second-generation space-based GW detectors as a shadow within a complex diffraction pattern.

B. McKernan; K. E. S. Ford; B. Kocsis; Z. Haiman

2014-08-28T23:59:59.000Z

400

The thermodynamics of a gravitating vacuum  

E-Print Network [OSTI]

In the present days of modern cosmology it is assumed that the main ingredient to cosmic energy presently is vacuum energy with an energy density $\\epsilon_\\mathrm{vac}$ that is constant over the cosmic evolution. In this paper here we show, however, that this assumption of constant vacuum energy density is unphysical, since it conflicts with the requirements of cosmic thermodynamics. We start from the total vacuum energy including the negatively valued gravitational binding energy and show that cosmic thermodynamics then requires that the cosmic vacuum energy density can only vary with cosmic scale $R=R(t)$ according to $\\epsilon _\\mathrm{vac}\\sim R^{-\

M. Heyl; H. J. Fahr; M. Siewert

2014-12-09T23:59:59.000Z

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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401

Gravitational Phase Transition of Heavy Neutrino Matter  

E-Print Network [OSTI]

We study the phase transition of a system of self-gravitating neutrinos in the presence of a large radiation density background in the framework of the Thomas-Fermi model. We show that, by cooling a non-degenerate gas of massive neutrinos below some critical temperature, a condensed phase emerges, consisting of quasi-degenerate supermassive neutrino stars. These compact dark objects could play an important role in structure formation in this universe, as they might in fact provide the seeds for galactic nuclei and quasi-stellar objects.

Neven Bilic; Raoul D. Viollier

1996-07-16T23:59:59.000Z

402

Grand Unification and Enhanced Quantum Gravitational Effects  

SciTech Connect (OSTI)

In grand unified theories with large numbers of fields, renormalization effects significantly modify the scale at which quantum gravity becomes strong. This in turn can modify the boundary conditions for coupling constant unification, if higher dimensional operators induced by gravity are taken into consideration. We show that the generic size of, and the uncertainty in, these effects from gravity can be larger than the two-loop corrections typically considered in renormalization group analyses of unification. In some cases, gravitational effects of modest size can render unification impossible.

Calmet, Xavier [Catholic University of Louvain, Center for Particle Physics and Phenomenology, 2, Chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium); Hsu, Stephen D. H.; Reeb, David [Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403 (United States)

2008-10-24T23:59:59.000Z

403

Vacuum fluctuations for spherical gravitational impulsive waves  

E-Print Network [OSTI]

We propose a method for calculating vacuum fluctuations on the background of a spherical impulsive gravitational wave which results in a finite expression for the vacuum expectation value of the stress-energy tensor. The method is based on first including a cosmological constant as an auxiliary constant. We show that the result for the vacuum expectation value of the stress-energy tensor in second-order perturbation theory is finite if both the cosmological constant and the infrared parameter tend to zero at the same rate.

M. Hortaçsu

1998-04-30T23:59:59.000Z

404

Alternative Gravitational Theories in Four Dimensions  

E-Print Network [OSTI]

We argue that from the point of view of gauge theory and of an appropriate interpretation of the interferometer experiments with matter waves in a gravitational field, the Einstein-Cartan theory is the best theory of gravity available. Alternative viable theories are general relativity and a certain teleparallelism model. Objections of Ohanian and Ruffini against the Einstein-Cartan theory are discussed. Subsequently we list the papers which were read at the `Alternative 4D Session' and try to order them, at least partially, in the light of the structures discussed.

Friedrich W. Hehl

1997-12-26T23:59:59.000Z

405

FROM DUST TO PLANETESIMALS: CRITERIA FOR GRAVITATIONAL INSTABILITY OF SMALL PARTICLES IN GAS  

SciTech Connect (OSTI)

Dust particles sediment toward the midplanes of protoplanetary disks, forming dust-rich sublayers encased in gas. What densities must the particle sublayer attain before it can fragment by self-gravity? We describe various candidate threshold densities. One of these is the Roche density, which is that required for a strengthless satellite to resist tidal disruption by its primary. Another is the Toomre density, which is that required for de-stabilizing self-gravity to defeat the stabilizing influences of pressure and rotation. We show that for sublayers containing aerodynamically well-coupled dust, the Toomre density exceeds the Roche density by many (up to about four) orders of magnitude. We present three-dimensional shearing box simulations of self-gravitating, stratified, dust-gas mixtures to test which of the candidate thresholds is relevant for collapse. All of our simulations indicate that the larger Toomre density is required for collapse. This result is sensible because sublayers are readily stabilized by pressure. Sound-crossing times for thin layers are easily shorter than free-fall times, and the effective sound speed in dust-gas suspensions decreases only weakly with the dust-to-gas ratio (as the inverse square root). Our findings assume that particles are small enough that their stopping times in gas are shorter than all other timescales. Relaxing this assumption may lower the threshold for gravitational collapse back down to the Roche criterion. In particular, if the particle stopping time becomes longer than the sound-crossing time, then sublayers may lose pressure support and become gravitationally unstable.

Shi, Ji-Ming; Chiang, Eugene, E-mail: jmshi@berkeley.edu [Department of Astronomy, UC Berkeley, Hearst Field Annex B-20, Berkeley, CA 94720-3411 (United States)] [Department of Astronomy, UC Berkeley, Hearst Field Annex B-20, Berkeley, CA 94720-3411 (United States)

2013-02-10T23:59:59.000Z

406

On the Unreasonable Effectiveness of post-Newtonian Theory in Gravitational-Wave Physics  

ScienceCinema (OSTI)

The first indirect detection of gravitational waves involved a binary system of neutron stars.  In the future, the first direct detection may also involve binary systems -- inspiralling and merging binary neutron stars or black holes. This means that it is essential to understand in full detail the two-body system in general relativity, a notoriously difficult problem with a long history. Post-Newtonian approximation methods are thought to work only under slow motion and weak field conditions, while numerical solutions of Einstein's equations are thought to be limited to the final merger phase.  Recent results have shown that post-Newtonian approximations seem to remain unreasonably valid well into the relativistic regime, while advances in numerical relativity now permit solutions for numerous orbits before merger.  It is now possible to envision linking post-Newtonian theory and numerical relativity to obtain a complete ``solution'' of the general relativistic two-body problem.  These solutions will play a central role in detecting and understanding gravitational wave signals received by interferometric observatories on Earth and in space.

Clifford M. Will

2010-01-08T23:59:59.000Z

407

Strengths and Weaknesses of Quantum Fingerprinting  

E-Print Network [OSTI]

We study the power of quantum fingerprints in the simultaneous message passing (SMP) setting of communication complexity. Yao recently showed how to simulate, with exponential overhead, classical shared-randomness SMP protocols by means of quantum SMP protocols without shared randomness ($Q^\\parallel$-protocols). Our first result is to extend Yao's simulation to the strongest possible model: every many-round quantum protocol with unlimited shared entanglement can be simulated, with exponential overhead, by $Q^\\parallel$-protocols. We apply our technique to obtain an efficient $Q^\\parallel$-protocol for a function which cannot be efficiently solved through more restricted simulations. Second, we tightly characterize the power of the quantum fingerprinting technique by making a connection to arrangements of homogeneous halfspaces with maximal margin. These arrangements have been well studied in computational learning theory, and we use some strong results obtained in this area to exhibit weaknesses of quantum fingerprinting. In particular, this implies that for almost all functions, quantum fingerprinting protocols are exponentially worse than classical deterministic SMP protocols.

Dmitry Gavinsky; Julia Kempe; Ronald de Wolf

2006-03-20T23:59:59.000Z

408

Degenerate weakly nonlinear elastic plane waves  

E-Print Network [OSTI]

Weakly nonlinear plane waves are considered in hyperelastic crystals. Evolution equations are derived at a quadratically nonlinear level for the amplitudes of quasi-longitudinal and quasi-transverse waves propagating in arbitrary anisotropic media. The form of the equations obtained depends upon the direction of propagation relative to the crystal axes. A single equation is found for all propagation directions for quasi-longitudinal waves, but a pair of coupled equations occurs for quasi-transverse waves propagating along directions of degeneracy, or acoustic axes. The coupled equations involve four material parameters but they simplify if the wave propagates along an axis of material symmetry. Thus, only two parameters arise for propagation along an axis of two-fold symmetry, and one for a three-fold axis. The transverse wave equations decouple if the axis is four-fold or higher. In the absence of a symmetry axis it is possible that the evolution equations of the quasi-transverse waves decouple if the third order elastic moduli satisfy a certain identity. The theoretical results are illustrated with explicit examples.

W?odzimierz Doma?ski; Andrew N. Norris

2008-12-18T23:59:59.000Z

409

Graphene transparency in weak magnetic fields  

E-Print Network [OSTI]

We carry out an explicit calculation of the vacuum polarization tensor for an effective low-energy model of monolayer graphene in the presence of a weak magnetic field of intensity $B$ perpendicularly aligned to the membrane. By expanding the quasiparticle propagator in the Schwinger proper time representation up to order $(eB)^2$, where $e$ is the unit charge, we find an explicitly transverse tensor, consistent with gauge invariance. Furthermore, assuming that graphene is radiated with monochromatic light of frequency $\\omega$ along the external field direction, from the modified Maxwell's equations we derive the intensity of transmitted light and the angle of polarization rotation in terms of the longitudinal ($\\sigma_{xx}$) and transverse ($\\sigma_{xy}$) conductivities. Corrections to these quantities, both calculated and measured, are of order $(eB)^2/\\omega^4$. Our findings generalize and complement previously known results reported in literature regarding the light absorption problem in graphene from the experimental and theoretical points of view, with and without external magnetic fields.

David Valenzuela; Saúl Hernández-Ortiz; Marcelo Loewe; Alfredo Raya

2014-10-20T23:59:59.000Z

410

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

411

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

412

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

413

Coherence oscillations between weakly coupled Bose-Hubbard dimers  

E-Print Network [OSTI]

We study theoretically the dynamics of two weakly-coupled Bose-Josephson junctions, prepared with the same particle number $N$ and Josephson excitation number $\

Christine Khripkov; Amichay Vardi

2014-05-11T23:59:59.000Z

414

Phenomenology and cosmology of weakly coupled string theory  

E-Print Network [OSTI]

ph/9805320 May 1998 Phenomenology and cosmology of weaklyThe important point for phenomenology is the decomposition2]. Implications for phenomenology and open questions The

Gaillard, Mary K.

1998-01-01T23:59:59.000Z

415

Reversing the Weak Quantum Measurement for a Photonic Qubit  

E-Print Network [OSTI]

We demonstrate the conditional reversal of a weak (partial-collapse) quantum measurement on a photonic qubit. The weak quantum measurement causes a nonunitary transformation of a qubit which is subsequently reversed to the original state after a successful reversing operation. Both the weak measurement and the reversal operation are implemented linear optically. The state recovery fidelity, determined by quantum process tomography, is shown to be over 94% for partial-collapse strength up to 0.9. We also experimentally study information gain due to the weak measurement and discuss the role of the reversing operation as an information erasure.

Yong-Su Kim; Young-Wook Cho; Young-Sik Ra; Yoon-Ho Kim

2009-03-18T23:59:59.000Z

416

Gravitational collapse of charged scalar fields  

E-Print Network [OSTI]

In order to study the gravitational collapse of charged matter we analyze the simple model of an self-gravitating massless scalar field coupled to the electromagnetic field in spherical symmetry. The evolution equations for the Maxwell-Klein-Gordon sector are derived in the 3+1 formalism, and coupled to gravity by means of the stress-energy tensor of these fields. To solve consistently the full system we employ a generalized Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation of General Relativity that is adapted to spherical symmetry. We consider two sets of initial data that represent a time symmetric spherical thick shell of charged scalar field, and differ by the fact that one set has zero global electrical charge while the other has non-zero global charge. For compact enough initial shells we find that the configuration doesn't disperse and approaches a final state corresponding to a sub-extremal Reissner-N\\"ordstrom black hole with $|Q|

Jose M. Torres; Miguel Alcubierre

2014-07-29T23:59:59.000Z

417

Unitarity and holography in gravitational physics  

SciTech Connect (OSTI)

Because the gravitational Hamiltonian is a pure boundary term on shell, asymptotic gravitational fields store information in a manner not possible in local field theories. This fact has consequences for both perturbative and nonperturbative quantum gravity. In perturbation theory about an asymptotically flat collapsing black hole, the algebra generated by asymptotic fields on future null infinity within any neighborhood of spacelike infinity contains a complete set of observables. Assuming that the same algebra remains complete at the nonperturbative quantum level, we argue that either (1) the S matrix is unitary or (2) the dynamics in the region near timelike, null, and spacelike infinity is not described by perturbative quantum gravity about flat space. We also consider perturbation theory about a collapsing asymptotically anti-de Sitter (AdS) black hole, where we show that the algebra of boundary observables within any neighborhood of any boundary Cauchy surface is similarly complete. Whether or not this algebra continues to be complete nonperturbatively, the assumption that the Hamiltonian remains a boundary term implies that information available at the AdS boundary at any one time t{sub 1} remains present at this boundary at any other time t{sub 2}.

Marolf, Donald [Physics Department, UCSB, Santa Barbara, California 93106 (United States)

2009-02-15T23:59:59.000Z

418

Gravitational Anomalies in the Solar System?  

E-Print Network [OSTI]

Mindful of the anomalous perihelion precession of Mercury discovered by U. Le Verrier in the second half of the nineteenth century and its successful explanation by A. Einstein with his General Theory of Relativity in the early years of the twentieth century, discrepancies among observed effects in our Solar system and their theoretical predictions on the basis of the currently accepted laws of gravitation applied to known bodies have the potential of paving the way for remarkable advances in fundamental physics. This is particularly important now more than ever, given that most of the Universe seems to be made of unknown substances dubbed Dark Matter and Dark Energy. Should this not be directly the case, Solar system's anomalies could anyhow lead to advancements in cumulative science, as shown to us by the discovery of Neptune in the first half of the nineteenth century. Moreover, investigations in one of such directions can serendipitously enrich the other one as well. The current status of some alleged gravitational anomalies in the Solar system is critically reviewed. They are: a) Possible anomalous advances of planetary perihelia; b) Unexplained orbital residuals of a recently discovered moon of Uranus (Mab); c) The lingering unexplained secular increase of the eccentricity of the orbit of the Moon; d) The so-called Faint Young Sun Paradox; e) The secular decrease of the mass parameter of the Sun; f) The Flyby Anomaly; g) The Pioneer Anomaly; and h) The anomalous secular increase of the astronomical unit

Lorenzo Iorio

2015-03-16T23:59:59.000Z

419

Quantum Mechanical Effects in Gravitational Collapse  

E-Print Network [OSTI]

In this thesis we investigate quantum mechanical effects to various aspects of gravitational collapse. These quantum mechanical effects are implemented in the context of the Functional Schr\\"odinger formalism. The Functional Schr\\"odinger formalism allows us to investigate the time-dependent evolutions of the quantum mechanical effects, which is beyond the scope of the usual methods used to investigate the quantum mechanical corrections of gravitational collapse. Utilizing the time-dependent nature of the Functional Schr\\"odinger formalism, we study the quantization of a spherically symmetric domain wall from the view point of an asymptotic and infalling observer, in the absence of radiation. To build a more realistic picture, we then study the time-dependent nature of the induced radiation during the collapse using a semi-classical approach. Using the domain wall and the induced radiation, we then study the time-dependent evolution of the entropy of the domain wall. Finally we make some remarks about the possible inclusion of backreaction into the system.

Eric Greenwood

2010-01-12T23:59:59.000Z

420

Energy and Momentum of a Class of Rotating Gravitational Waves  

E-Print Network [OSTI]

We calculate energy and momentum for a class of cylindrical rotating gravitational waves using Einstein and Papapetrou's prescriptions. It is shown that the results obtained are reduced to the special case of the cylindrical gravitational waves already available in the literature.

M. Sharif

2001-02-09T23:59:59.000Z

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.


421

Gravitational Potential Variations of the Sun and Moon for Estimation  

E-Print Network [OSTI]

Gravitational Potential Variations of the Sun and Moon for Estimation of Reservoir Compressibility by the moon and the sun. The potential variations are coupled to the reservoir pressure pulsations through for the gravitational potential due to the most impor- tant sources, the moon and the sun, must be obtained. Although

Firoozabadi, Abbas

422

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

2013-04-18T23:59:59.000Z

423

On multitemporal generalization of Newton’s gravitational law  

E-Print Network [OSTI]

A n-time generalization of Newton’s law (of universal gravitation) formula in N = n + d+1-dimensional space-time is conjectured. This formula implies a relation for effective N-dimensional gravitational constant Geff = Gcos 2 ?, where ? is the angle between the direction of motion of two particles in n-dimensional time manifold R n. 1

V. D. Ivashchuk

424

Positive, Negative and Neutral Law of Universal Gravitation  

E-Print Network [OSTI]

Abstract: According to the viewpoints of “one divides into two”, “one divides into three” (e.g. Neutrosophy) and “one divides into many”, at present there exist six kinds of matter in the universe altogether (one divides into six). If there exists the ordinary matter (called matter for short), there must exist its opposite. However there may exist more than one kind of its opposite, today the known opposites of matter may be the antimatter and dark matter; Other three kinds of matter are the neutral ones: the first neutral matter between matter and antimatter (Prof. Smarandache named it unmatter), the second neutral matter between matter and dark matter, and the third neutral matter between antimatter and dark matter. Similarly, if there exists the original “law of universal gravitation” (positive law of universal gravitation), there must exist its opposites (negative laws of universal gravitation), and the neutral ones (neutral laws of universal gravitation). According to this analysis, it is impossible to find the unified and ultimate gravitational theory. Key words: One divides into two; one divides into three; one divides into many; Neutrosophy; six kinds of matter; positive (original) law of universal gravitation; negative law of universal gravitation; neutral law of universal gravitation 1

Fu Yuhua; Fu Anjie; Zhao Ge

425

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

2009-10-21T23:59:59.000Z

426

Sub-millimeter tests of the gravitational inverse-square law.  

E-Print Network [OSTI]

??The Newtonian Law of Universal Gravitation states that the strength of the gravitational force between point test bodies falls as the inverse-square of the distance… (more)

Hoyle, Charles D., 1974-

2001-01-01T23:59:59.000Z

427

Modeling active electrolocation in weakly electric fish Habib Ammari  

E-Print Network [OSTI]

Modeling active electrolocation in weakly electric fish Habib Ammari Thomas Boulier Josselin 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

Garnier, Josselin

428

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

429

E-Print Network 3.0 - astronomically large lenses Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Art Congdon 12;12;Basic ... Source: Baker, Andrew J. - Department of Physics and Astronomy, Rutgers University Collection: Physics 2 LIGHT ON DARK MATTER WITH WEAK...

430

Stochastic Gravitational Wave Background from Exoplanets  

E-Print Network [OSTI]

Recent exoplanet surveys have predicted a very large population of planetary systems in our galaxy, more than one planet per star on the average, perhaps totalling about two hundred billion. These surveys, based on electro-magnetic observations, are limited to a very small neighbourhood of the solar system and the estimations rely on the observations of only a few thousand planets. On the other hand, orbital motions of planets around stars are expected to emit gravitational waves (GW), which could provide information about the planets not accessible to electro-magnetic astronomy. The cumulative effect of the planets, with periods ranging from few hours to several years, is expected to create a stochastic GW background (SGWB). We compute the characteristic GW strain of this background based on the observed distribution of planet parameters. We also show that the integrated extragalactic background is comparable or less than the galactic background at different frequencies. Our estimate shows that the net backg...

Ain, Anirban; Mitra, Sanjit

2015-01-01T23:59:59.000Z

431

Generalized gravitational entropy without replica symmetry  

E-Print Network [OSTI]

We explore several extensions of the generalized entropy construction of Lewkowycz and Maldacena, including a formulation that does not rely on preserving replica symmetry in the bulk. We show that an appropriately general ansatz for the analytically continued replica metric gives us the flexibility needed to solve the gravitational field equations beyond general relativity. As an application of this observation we study Einstein-Gauss-Bonnet gravity with a small Gauss-Bonnet coupling and derive the condition that the holographic entanglement entropy must be evaluated on a surface which extremizes the Jacobson-Myers entropy. We find that in both general relativity and Einstein-Gauss-Bonnet gravity replica symmetry breaking terms are permitted by the field equations, suggesting that they do not generically vanish.

Joan Camps; William R. Kelly

2015-01-13T23:59:59.000Z

432

Gravitational Instability of Yang-Mills Cosmologies  

E-Print Network [OSTI]

The gravitational instability of Yang-Mills cosmologies is numerically studied with the hamiltonian formulation of the spherically symmetric Einstein-Yang-Mills equations with SU(2) gauge group. On the short term, the expansion dilutes the energy densities of the Yang-Mills fluctuations due to their conformal invariance. In this early regime, the gauge potentials appear oscillating quietly in an interaction potential quite similar to the one of the homogeneous case. However, on the long term, the expansion finally becomes significantly inhomogeneous and no more mimics a conformal transformation of the metric. Thereafter, the Yang-Mills fluctuations enter a complex non-linear regime, accompanied by diffusion, while their associated energy contrasts grow.

A. Fuzfa

2003-10-06T23:59:59.000Z

433

Phenomenological gravitational waveforms from spinning coalescing binaries  

E-Print Network [OSTI]

An accurate knowledge of the coalescing binary gravitational waveform is crucial for experimental searches as the ones performed by the LIGO-Virgo collaboration. Following an earlier paper by the same authors we refine the construction of analytical phenomenological waveforms describing the signal sourced by generically spinning binary systems. The gap between the initial inspiral part of the waveform, described by spin-Taylor approximants, and its final ring-down part, described by damped exponentials, is bridged by a phenomenological phase calibrated by comparison with the dominant spherical harmonic mode of a set of waveforms including both numerical and phenomenological waveforms of different type. All waveforms considered describe equal mass systems. The Advanced LIGO noise-weighted overlap integral between the numerical and phenomenological waveforms presented here ranges between 0.95 and 0.99 for a wide span of mass values.

R. Sturani; S. Fischetti; L. Cadonati; G. M. Guidi; J. Healy; D. Shoemaker; A. Vicere'

2011-06-23T23:59:59.000Z

434

Mother templates for gravitational wave chirps  

E-Print Network [OSTI]

Templates used in a search for binary black holes and neutron stars in gravitational wave interferometer data will have to be computed on-line since the computational storage and retrieval costs for the template bank are too expensive. The conventional dimensionless variable $T=(c^3/Gm)t,$ where $m$ is the total mass of a binary, in the time-domain and a not-so-conventional velocity-like variable $v=(\\pi Gm f)^{1/3}$ in the Fourier-domain, render the phasing of the waves independent of the total mass of the system enabling the construction of {\\it mother templates} that depend only on the mass ratio of a black hole binary. Use of such mother templates in a template bank will bring about a reduction in computational costs up to a factor of 10 and a saving on storage by a factor of 100.

B. S. Sathyaprakash

2000-10-11T23:59:59.000Z

435

Nanogap Transducer for Broadband Gravitational Wave Detection  

E-Print Network [OSTI]

By changing from a resonant multimode paradigm to a free mass paradigm for transducers in resonant mass gravitational wave detection, an array of six spheres can achieve a sensitivity response curve competitive with interferometers, being as sensitive as GEO600 and TAMA300 in the 3 to 6 kHz band and more sensitive than LIGO for 50 percent of the 6 to 10 kHz band. We study how to assemble a klystron resonant cavity that has a 1 nm gap by understanding the stability of the forces applied at it (Casimir force, elastic force, weight). This approach has additional benefits. First, due to the relatively inexpensive nature of this technology (around US$ 1 million), it is accessible to a broader part of the world scientific community. Additionally, spherical resonant mass detectors have the ability to discern both the direction and polarization resolutions.

Guilherme L. Pimentel; Odylio D. Aguiar; Michael E. Tobar; Joaquim J. Barroso; Rubens de M. Marinho

2009-10-06T23:59:59.000Z

436

Gravitational Dynamics in an Expanding Universe  

E-Print Network [OSTI]

The dynamical evolution of collisionless particles in an expanding background is described. After discussing qualitatively the key features, the gravitational clustering of collisionless particles in an expanding universe is modelled using some simple physical ideas. I show that it is indeed possible to understand the nonlinear clustering in terms of three well defined regimes: (1) linear regime (2) quasilinear regime which is dominated by scale-invariant radial infall and (3) nonlinear regime dominated by nonradial motions and mergers. Modelling each of these regimes separately I show how the nonlinear two point correlation function can be related to the linear correlation function in hierarchical models. This analysis leads to results which are in good agreement with numerical simulations thereby providing an explanation for numerical results. The ideas presented here will also serve as a powerful analytical tool to investigate nonlinear clustering in different models. Several implications of the result are discussed.

T. Padmanabhan

1995-10-05T23:59:59.000Z

437

Nonlinear Gravitational Clustering in Expanding Universe  

E-Print Network [OSTI]

The gravitational clustering of collisionless particles in an expanding universe is modelled using some simple physical ideas. I show that it is possible to understand the nonlinear clustering in terms of three well defined regimes: (1) linear regime; (2) quasilinear regime which is dominated by scale-invariant radial infall and (3) nonlinear regime dominated by nonradial motions and mergers. Modelling each of these regimes separately I show how the nonlinear two point correlation function can be related to the linear correlation function in hierarchical models. This analysis leads to results which are in good agreement with numerical simulations thereby providing an explanation for numerical results. Using this model and some simple extensions, it is possible to understand the transfer of power from large to small scales and the behaviour of higher order correlation functions. The ideas presented here will also serve as a powerful analytical tool to investigate nonlinear clustering in different models.

T. Padmanabhan

1996-07-19T23:59:59.000Z

438

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

2014-02-25T23:59:59.000Z

439

Gravitating non-Abelian cosmic strings  

E-Print Network [OSTI]

In this paper we study regular cosmic string solutions of the non-Abelian Higgs model coupled with the Einstein gravity. In order to do that, we constructed a set of coupled differential ordinary equation. Because there is no closed solution for this set of equations, we solve it numerically. The solutions that we are interested in asymptote to a flat space-time with a planar angle deficit. This model under consideration present two bosonic sectors, besides the non-Abelian gauge one, coupled minimally with the gravitational fields. The two bosonic sectors may present a direct coupling, which plays an important role on the behavior of the matter and gauge fields and also on the behavior on the geometry of the spacetime. We explicitly analyze the behaviors of the energy density and planar angle deficit as function of the energy scale where the gauge symmetry is spontaneously broken and the coupling interaction between the bosonic sectors.

Santo, Antônio de Padua

2015-01-01T23:59:59.000Z

440

V819 TAU: A RARE WEAK-LINED T TAURI STAR WITH A WEAK INFRARED EXCESS  

SciTech Connect (OSTI)

We use Spitzer data to infer that the small infrared excess of V819 Tau, a weak-lined T Tauri star in Taurus, is real and not attributable to a 'companion' 10'' to the south. We do not confirm the mid-infrared excess in HBC 427 and V410 X-ray 3, which are also non-accreting T Tauri stars in the same region; instead, for the former object, the excess arises from a red companion 9'' to the east. A single-temperature blackbody fit to the continuum excess of V819 Tau implies a dust temperature of 143 K; however, a better fit is achieved when the weak 10 and 20 mum silicate emission features are also included. We infer a disk of sub-mum silicate grains between about 1 AU and several 100 AU with a constant surface density distribution. The mid-infrared excess of V819 Tau can be successfully modeled with dust composed mostly of small amorphous olivine grains at a temperature of 85 K, and most of the excess emission is optically thin. The disk could still be primordial, but gas-poor and therefore short-lived, or already at the debris disk stage, which would make it one of the youngest debris disk systems known.

Furlan, E. [Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 264-767, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Forrest, W. J.; Manoj, P.; Kim, K. H.; Watson, Dan M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Sargent, B. A., E-mail: Elise.Furlan@jpl.nasa.go, E-mail: forrest@pas.rochester.ed, E-mail: manoj@pas.rochester.ed, E-mail: khkim@pas.rochester.ed, E-mail: dmw@pas.rochester.ed, E-mail: sargent@stsci.ed [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2009-12-01T23:59:59.000Z

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.


441

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

SciTech Connect (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 are required to find 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 noninvariant 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 and we find new solutions corresponding to maximal symmetry restricted to a lower dimensional subspace. We also consider normalizable, linearized gravitational perturbations around the anti-de Sitter background. We show to second order, that these gravitational fluctuations carry zero energy momentum. Finally 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. This offers a way of eschewing the recent suggestion and its consequences [E. Flanagan, Phys. Rev. D 74, 023002 (2006).] that the conformal symmetry could be quarantined to a sterile sector of the theory by choosing an appropriate field redefinition.

Bouchami, Jihene [Groupe de physique des particules, Departement de physique, Universite de Montreal, Case Postale 6128, succursale Centre-ville, Montreal, Quebec, H3C 3J7 (Canada); Paranjape, M. B. [Groupe de physique des particules, Departement de physique, Universite de Montreal, Case Postale 6128, succursale Centre-ville, Montreal, Quebec, H3C 3J7 (Canada); Center for Quantum Spacetime, Department of Physics, Sogang University, Shinsu-dong 1, Mapo-gu, Seoul, 121-742 (Korea, Republic of)

2008-08-15T23:59:59.000Z

442

LIMITS ON THE STOCHASTIC GRAVITATIONAL WAVE BACKGROUND FROM THE NORTH AMERICAN NANOHERTZ OBSERVATORY FOR GRAVITATIONAL WAVES  

SciTech Connect (OSTI)

We present an analysis of high-precision pulsar timing data taken as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We have observed 17 pulsars for a span of roughly five years using the Green Bank and Arecibo radio telescopes. We analyze these data using standard pulsar timing models, with the addition of time-variable dispersion measure and frequency-variable pulse shape terms. Sub-microsecond timing residuals are obtained in nearly all cases, and the best rms timing residuals in this set are {approx}30-50 ns. We present methods for analyzing post-fit timing residuals for the presence of a gravitational wave signal with a specified spectral shape. These optimally take into account the timing fluctuation power removed by the model fit, and can be applied to either data from a single pulsar, or to a set of pulsars to detect a correlated signal. We apply these methods to our data set to set an upper limit on the strength of the nHz-frequency stochastic supermassive black hole gravitational wave background of h{sub c} (1 yr{sup -1}) < 7 Multiplication-Sign 10{sup -15} (95%). This result is dominated by the timing of the two best pulsars in the set, PSRs J1713+0747 and J1909-3744.

Demorest, P. B.; Ransom, S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)] [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Ferdman, R. D.; Kaspi, V. M. [Department of Physics, McGill University, 3600 rue Universite, Montreal, QC H3A 2T8 (Canada)] [Department of Physics, McGill University, 3600 rue Universite, Montreal, QC H3A 2T8 (Canada); Gonzalez, M. E.; Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)] [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Nice, D. [Department of Physics, Lafayette College, Easton, PA 18042 (United States)] [Department of Physics, Lafayette College, Easton, PA 18042 (United States); Arzoumanian, Z. [Center for Research and Exploration in Space Science and Technology and X-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)] [Center for Research and Exploration in Space Science and Technology and X-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Brazier, A.; Cordes, J. M. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)] [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Burke-Spolaor, S.; Lazio, J. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91106 (United States)] [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91106 (United States); Chamberlin, S. J.; Ellis, J.; Giampanis, S. [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)] [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States); Finn, L. S. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)] [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Freire, P. [Max-Planck-Institut fur Radioastronomie, D-53121 Bonn (Germany)] [Max-Planck-Institut fur Radioastronomie, D-53121 Bonn (Germany); Jenet, F. [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States)] [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Lommen, A. N. [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States)] [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); McLaughlin, M. [Department of Physics, West Virginia University, P.O. Box 6315, Morgantown, WV 26505 (United States)] [Department of Physics, West Virginia University, P.O. Box 6315, Morgantown, WV 26505 (United States); and others

2013-01-10T23:59:59.000Z

443

Large Deviations in the Superstable Weakly Imperfect Bose Gas 1 Large Deviations in the Superstable Weakly Imperfect Bose Gas  

E-Print Network [OSTI]

of the condensate. More interesting for our analysis is a discontinuity of the particle density from #- > 0Large Deviations in the Superstable Weakly Imperfect Bose Gas 1 Large Deviations in the Superstable Weakly Imperfect Bose Gas J.­B. Bru a and V.A. Zagrebnov b a FakultË?at fË?ur Physik, UniversitË?at Wien

444

VISCOSITY IN PLANETARY RINGS WITH SPINNING SELF-GRAVITATING PARTICLES  

SciTech Connect (OSTI)

Using local N-body simulation, we examine viscosity in self-gravitating planetary rings. We investigate the dependence of viscosity on various parameters in detail, including the effects of particle surface friction. In the case of self-gravitating rings with low optical depth, viscosity is determined by particle random velocity. Inclusion of surface friction slightly reduces both random velocity and viscosity when particle random velocity is determined by inelastic collisions, while surface friction slightly increases viscosity when gravitational encounters play a major role in particle velocity evolution, so that viscous heating balances with increased energy dissipation at collisions due to surface friction. We find that including surface friction changes viscosity in dilute rings up to a factor of about two. In the case of self-gravitating dense rings, viscosity is significantly increased due to the effects of gravitational wakes, and we find that varying restitution coefficients also change viscosity in such dense rings by a factor of about two. We confirm that our numerical results for viscosity in dense rings with gravitational wakes can be well approximated by a semianalytic expression that is consistent with a previously obtained formula. However, we find that this formula seems to overestimate viscosity in dense rings far from the central planet, where temporary gravitational aggregates form. We derive semianalytic expressions that reproduce our numerical results well for the entire range of examined parameters.

Yasui, Yuki; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Daisaka, Hiroshi [Graduate School of Commerce and Management, Hitotsubashi University, Tokyo 186-8601 (Japan)

2012-05-15T23:59:59.000Z

445

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

446

Gauge Invariant Effective Stress-Energy Tensors for Gravitational Waves  

E-Print Network [OSTI]

It is shown that if a generalized definition of gauge invariance is used, gauge invariant effective stress-energy tensors for gravitational waves and other gravitational perturbations can be defined in a much larger variety of circumstances than has previously been possible. In particular it is no longer necessary to average the stress-energy tensor over a region of spacetime which is larger in scale than the wavelengths of the waves and it is no longer necessary to restrict attention to high frequency gravitational waves.

Paul R. Anderson

1996-09-09T23:59:59.000Z

447

Gravitational wave generation in power-law inflationary models  

E-Print Network [OSTI]

We investigate the generation of gravitational waves in power-law inflationary models. The energy spectrum of the gravitational waves is calculated using the method of continuous Bogoliubov coefficients. We show that, by looking at the interval of frequencies between 10^(-5) and 10^5 Hz and also at the GHz range, important information can be obtained, both about the inflationary period itself and about the thermalization regime between the end of inflation and the beginning of the radiation-dominated era. We thus deem the development of gravitational wave detectors, covering the MHz/GHz range of frequencies, to be an important task for the future.

Paulo M. Sá; Alfredo B. Henriques

2008-06-06T23:59:59.000Z

448

Generalized Gravitational Entropy of Interacting Scalar Field and Maxwell Field  

E-Print Network [OSTI]

The generalized gravitational entropy proposed by Lewkowycz and Maldacena in recent is extended to the interacting real scalar field and Maxwell field system. Using the BTZ geometry we first investigate the case of free real scalar field and then show a possible way to calculate the entropy of the interacting scalar field. Next, we investigate the Maxwell field system. We exactly solve the wave equation and calculate the analytic value of the generalized gravitational entropy. We also use the Einstein equation to find the effect of backreaction of the Maxwell field on the area of horizon. The associated modified area law is consistent with the generalized gravitational entropy.

Wung-Hong Huang

2014-11-11T23:59:59.000Z

449

Quasar Proper Motions and Low-Frequency Gravitational Waves  

E-Print Network [OSTI]

We report observational upper limits on the mass-energy of the cosmological gravitational-wave background, from limits on proper motions of quasars. Gravitational waves with periods longer than the time span of observations produce a simple pattern of apparent proper motions over the sky, composed primarily of second-order transverse vector spherical harmonics. A fit of such harmonics to measured motions yields a 95%-confidence limit on the mass-energy of gravitational waves with frequencies <2e-9 Hz, of <0.11/h*h times the closure density of the universe.

Carl R. Gwinn; T. Marshall Eubanks; Ted Pyne; Mark Birkinshaw; Demetrios N. Matsakis

1996-10-12T23:59:59.000Z

450

The Energy-Momentum Tensor in General Relativity and in Alternative Theories of Gravitation, and the Gravitational vs. Inertial Mass  

E-Print Network [OSTI]

We establish a general relation between the canonical energy-momentum tensor of Lagrangian dynamics and the tensor that acts as the source of the gravitational field in Einstein's equations, and we show that there is a discrepancy between these tensors when there are direct nonminimal couplings between matter and the Riemann tensor. Despite this discrepancy, we give a general proof of the exact equality of the gravitational and inertial masses for any arbitrary system of matter and gravitational fields, even in the presence of nonminimal second-derivative couplings and-or linear or nonlinear second-derivative terms of any kind in the Lagrangian. The gravitational mass is defined by the asymptotic Newtonian potential at large distance from the system, and the inertial mass is defined by the volume integral of the energy density determined from the canonical energy-momentum tensor. In the Brans-Dicke scalar field theory, we establish that the nonminimal coupling and long range of the scalar field leads to an inequality between the gravitational and inertial masses, and we derive an exact formula for this inequality and confirm that it is approximately proportional to the gravitational self-energy (the Nordvedt effect), but with a constant of proportionality different from what is claimed in the published literature in calculations based on the PPN scheme. Similar inequalities of gravitational and inertial masses are expected to occur in other scalar and vector theories.

Hans C. Ohanian

2013-02-28T23:59:59.000Z

451

Weak chimeras in minimal networks of coupled phase oscillators  

E-Print Network [OSTI]

We suggest a definition for a type of chimera state that appears in networks of indistinguishable phase oscillators. Defining a "weak chimera" as a type of invariant set showing partial frequency synchronization, we show that this means they cannot appear in phase oscillator networks that are either globally coupled or too small. We exhibit various networks of four, six and ten indistinguishable oscillators where weak chimeras exist with various dynamics and stabilities. We examine the role of Kuramoto-Sakaguchi coupling in giving degenerate (neutrally stable) families of weak chimera states in these example networks.

Peter Ashwin; Oleksandr Burylko

2014-12-10T23:59:59.000Z

452

Gravitational and electric energies in collapse of spherically thin capacitor  

E-Print Network [OSTI]

In our previous article (PHYSICAL REVIEW D 86, 084004 (2012)), we present a study of strong oscillating electric fields and electron-positron pair-production in gravitational collapse of a neutral stellar core at or over nuclear densities. In order to understand the back-reaction of such electric energy building and radiating on collapse, we adopt a simplified model describing the collapse of a spherically thin capacitor to give an analytical description how gravitational energy is converted to both kinetic and electric energies in collapse. It is shown that (i) averaged kinetic and electric energies are the same order, about an half of gravitational energy of spherically thin capacitor in collapse; (ii) caused by radiating and rebuilding electric energy, gravitational collapse undergoes a sequence of "on and off" hopping steps in the microscopic Compton scale. Although such a collapse process is still continuous in terms of macroscopic scales, it is slowed down as kinetic energy is reduced and collapsing tim...

Ruffini, Remo

2013-01-01T23:59:59.000Z

453

Techniques for improving the readout sensitivity of gravitational wave antennae  

E-Print Network [OSTI]

The detection of gravitational waves (GWs) from astrophysical sources shows promise as a new method to probe extremely energetic phenomena and test the strong field limit of the general theory of relativity. The era of the ...

Smith-Lefebvre, Nicolás de Mateo

2012-01-01T23:59:59.000Z

454

Two quantum effects in the theory of gravitation  

E-Print Network [OSTI]

We will discuss two methods by which the formalism of quantum field theory can be included in calculating the physical effects of gravitation. In the first of these, the consequences of treating general relativity as an ...

Robinson, Sean Patrick, 1977-

2005-01-01T23:59:59.000Z

455