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1

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

2

Gravitational lensing  

Science Journals Connector (OSTI)

Gravitational lensing has developed into one of the most powerful tools for the analysis of the dark universe. This review summarizes the theory of gravitational lensing, its main current applications and representative results achieved so far. It has two parts. In the first, starting from the equation of geodesic deviation, the equations of thin and extended gravitational lensing are derived. In the second, gravitational lensing by stars and planets, galaxies, galaxy clusters and large-scale structures is discussed and summarized.

Matthias Bartelmann

2010-01-01T23:59:59.000Z

3

Physical component analysis of galaxy cluster weak gravitational lensing data  

Science Journals Connector (OSTI)

......Optimization schemes for locating the best-fitting point...by weak-lensing data sets: we find the evidence...sample corresponds to a set of haloes that provide...a consequence of the domination of clusters by a single...methods: the natural basis set of elliptical NFW-profile......

Phil Marshall

2006-11-01T23:59:59.000Z

4

Weighing the Cosmological Energy Contents with Weak Gravitational Lensing  

E-Print Network [OSTI]

Bernardeau et al. (1997), using perturbation theory, showed that the skewness of the large-scale lensing-convergence, or projected mass density, could be used to constrain $\\Omega_m$, the matter content of the universe. On the other hand, deep weak-lensing field surveys in the near future will likely measure the convergence on small angular scales (energy contents, through their influence on the global geometrical distances and fluctuation growth rate. Moreover, nonlinear clustering appears to enhance the differences between predictions of the convergence skewness for a range of models. Hence, in addition to constraining $\\Omega_m$, the small-scale convergence skewness from future deep several- degree-wide surveys can be used to differentiate between curvature dominated and cosmological constant ($\\Lambda$) dominated models, as well as to constrain the equation of state of a quintessence component, thereby distinguishing $\\Lambda$ from quintessence as well. Finally, our method can be easily generalized to other measures such as aperture mass statistics.

Lam Hui

1999-02-19T23:59:59.000Z

5

A step towards testing general relativity using weak gravitational lensing and redshift surveys  

E-Print Network [OSTI]

Using the linear theory of perturbations in General Relativity, we express a set of consistency relations that can be observationally tested with current and future large scale structure surveys. We then outline a stringent model-independent program to test gravity on cosmological scales. We illustrate the feasibility of such a program by jointly using several observables like peculiar velocities, galaxy clustering and weak gravitational lensing. After addressing possible observational or astrophysical caveats like galaxy bias and redshift uncertainties, we forecast in particular how well one can predict the lensing signal from a cosmic shear survey using an over-lapping galaxy survey. We finally discuss the specific physics probed this way and illustrate how $f(R)$ gravity models would fail such a test.

Yong-Seon Song; Olivier Doré

2008-12-01T23:59:59.000Z

6

What is Gravitational Lensing?  

SciTech Connect (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

2009-07-31T23:59:59.000Z

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

Cosmology with weak lensing surveys  

Science Journals Connector (OSTI)

...and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g...Large-aperture Synoptic Survey Telescope will play a major...and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g...

2005-01-01T23:59:59.000Z

10

Weak lensing and dark energy  

Science Journals Connector (OSTI)

We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance. With reasonable prior information on other cosmological parameters, we find that a survey covering 1000 sq deg down to a limiting magnitude of R=27 can impose constraints comparable to those expected from upcoming type Ia supernova and number-count surveys. This result, however, is contingent on the control of both observational and theoretical systematics. Concentrating on the latter, we find that the nonlinear power spectrum of matter perturbations and the redshift distribution of source galaxies both need to be determined accurately in order for weak lensing to achieve its full potential. Finally, we discuss the sensitivity of the three-point statistics to dark energy.

Dragan Huterer

2002-02-12T23:59:59.000Z

11

On the role of ? in gravitational lensing  

Science Journals Connector (OSTI)

The cosmological constant ? affects gravitational lensing phenomena. Related effect can be studied in the framework of the Schwarzschild?de Sitter space?time in the weak deflection limit. The main contribution of ? can be accounted for by a proper use of angular diameter distances. For near lenses and static observers unresolved images are slightly de?magnified the radius of the Einstein ring decreases and the time delay increases. The effect is however negligible. Two novel contributions which show up in a cosmological context are also discussed. First a term ????=?2mb?/3 has to be added to the bending angle where m is the lens mass and b the impact parameter. Second ? brings about a difference in the redshifts of multiple images. Both effects are quite small for real astrophysical systems ??? ? ?0.1?? arcsec and ?z s ?10 ?7 .

Mauro Sereno

2010-01-01T23:59:59.000Z

12

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

13

Weak field limit of Reissner-Nordström black hole lensing  

Science Journals Connector (OSTI)

We study gravitational lensing by a Reissner-Nordström black hole in the weak field limit. We obtain the basic equations for the deflection angle and time delay and find analytical expressions for the positions and amplifications of the primary and secondary images. Because of a net positive charge, the separation between images increases, but no change in the total magnification occurs.

Mauro Sereno

2004-01-13T23:59:59.000Z

14

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

15

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

16

The Third Gravitational Lensing Accuracy Testing (GREAT3) Challenge Handbook  

E-Print Network [OSTI]

The GRavitational lEnsing Accuracy Testing 3 (GREAT3) challenge is the third in a series of image analysis challenges, with a goal of testing and facilitating the development of methods for analyzing astronomical images that will be used to measure weak gravitational lensing. This measurement requires extremely precise estimation of very small galaxy shape distortions, in the presence of far larger intrinsic galaxy shapes and distortions due to the blurring kernel caused by the atmosphere, telescope optics, and instrumental effects. The GREAT3 challenge is posed to the astronomy, machine learning, and statistics communities, and includes tests of three specific effects that are of immediate relevance to upcoming weak lensing surveys, two of which have never been tested in a community challenge before. These effects include realistically complex galaxy models based on high-resolution imaging from space; spatially varying blurring kernel; and combination of multiple different exposures. To facilitate entry by p...

Mandelbaum, Rachel; Bosch, James; Chang, Chihway; Courbin, Frederic; Gill, Mandeep; Jarvis, Mike; Kannawadi, Arun; Kacprzak, Tomasz; Lackner, Claire; Leauthaud, Alexie; Miyatake, Hironao; Nakajima, Reiko; Rhodes, Jason; Simet, Melanie; Zuntz, Joe; Armstrong, Bob; Bridle, Sarah; Coupon, Jean; Dietrich, Jörg P; Gentile, Marc; Heymans, Catherine; Jurling, Alden S; Kent, Stephen M; Kirkby, David; Margala, Daniel; Massey, Richard; Melchior, Peter; Peterson, John; Roodman, Aaron; Schrabback, Tim

2013-01-01T23:59:59.000Z

17

Neutrino Mass and Dark Energy from Weak Lensing  

Science Journals Connector (OSTI)

Weak gravitational lensing of background galaxies by intervening matter directly probes the mass distribution in the Universe. This distribution is sensitive to both the dark energy and neutrino mass. We examine the potential of lensing experiments to measure features of both simultaneously. Focusing on the radial information contained in a future deep 4000??deg2 survey, we find that the expected (1-?) error on a neutrino mass is 0.1 eV, if the dark-energy parameters are allowed to vary. The constraints on dark-energy parameters are similarly restrictive, with errors on w of 0.09.

Kevork N. Abazajian and Scott Dodelson

2003-07-24T23:59:59.000Z

18

Hopfield Neural Network deconvolution for weak lensing measurement  

E-Print Network [OSTI]

Weak gravitational lensing has the potential to place tight constraints on the equation of the state of dark energy. However, this will only be possible if shear measurement methods can reach the required level of accuracy. We present a new method to measure the ellipticity of galaxies used in weak lensing surveys. The method makes use of direct deconvolution of the data by the total Point Spread Function (PSF). We adopt a linear algebra formalism that represents the PSF as a Toeplitz matrix. This allows us to solve the convolution equation by applying the Hopfield Neural Network iterative scheme. The ellipticity of galaxies in the deconvolved images are then measured using second order moments of the autocorrelation function of the images. To our knowledge, it is the first time full image deconvolution is used to measure weak lensing shear. We apply our method to the simulated weak lensing data proposed in the GREAT10 challenge and obtain a quality factor of Q=87. This result is obtained after applying image...

Nurbaeva, Guldariya; Courbin, Frederic; Meylan, Georges

2014-01-01T23:59:59.000Z

19

Inclination Effects in Spiral Galaxy Gravitational Lensing  

E-Print Network [OSTI]

Spheroidal components of spiral galaxies have been considered the only dynamically important component in gravitational lensing studies thus far. Here we point out that including the disk component can have a significant effect, depending on the disk inclination, on a variety of lensing properties that are relevant to present studies and future surveys. As an example, we look at the multiple image system B1600+434, recently identified as being lensed by a spiral galaxy. We find that including the disk component one can understand the fairly large image separation as being due to the inclination of a typical spiral, rather than the presence of a very massive halo. The fairly low magnification ratio can also be readily understood if the disk is included. We also discuss how such lensed systems might allow one to constrain parameters of spiral galaxies such as a disk-to-halo mass ratio, and disk mass scale length. Another example we consider is the quasar multiple-lensing cross section, which we find can increase many-fold at high inclination for a typical spiral. Finally, we discuss the changes in the gravitational lensing effects on damped Lyman alpha systems (DLAS) when disk lensing is included.

Ariyeh Maller; Ricardo Flores; Joel Primack

1997-01-16T23:59:59.000Z

20

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

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

A New Shear Estimator for Weak Lensing Observations  

E-Print Network [OSTI]

We present a new shear estimator for weak lensing observations which properly accounts for the effects of a realistic point spread function (PSF). Images of faint galaxies are subject to gravitational shearing followed by smearing with the instrumental and/or atmospheric PSF. We construct a `finite resolution shear operator' which when applied to an observed image has the same effect as a gravitational shear applied prior to smearing. This operator allows one to calibrate essentially any shear estimator. We then specialize to the case of weighted second moment shear estimators. We compute the shear polarizability which gives the response of an individual galaxy's polarization to a gravitational shear. We then compute the response of the population of galaxies, and thereby construct an optimal weighting scheme for combining shear estimates from galaxies of various shapes, luminosities and sizes. We define a figure of merit --- an inverse shear variance per unit solid angle --- which characterizes the quality o...

Kaiser, N

1999-01-01T23:59:59.000Z

22

A New Shear Estimator for Weak Lensing Observations  

E-Print Network [OSTI]

We present a new shear estimator for weak lensing observations which properly accounts for the effects of a realistic point spread function (PSF). Images of faint galaxies are subject to gravitational shearing followed by smearing with the instrumental and/or atmospheric PSF. We construct a `finite resolution shear operator' which when applied to an observed image has the same effect as a gravitational shear applied prior to smearing. This operator allows one to calibrate essentially any shear estimator. We then specialize to the case of weighted second moment shear estimators. We compute the shear polarizability which gives the response of an individual galaxy's polarization to a gravitational shear. We then compute the response of the population of galaxies, and thereby construct an optimal weighting scheme for combining shear estimates from galaxies of various shapes, luminosities and sizes. We define a figure of merit --- an inverse shear variance per unit solid angle --- which characterizes the quality of image data for shear measurement. The new method is tested with simulated image data. We discuss the correction for anisotropy of the PSF and propose a new technique involving measuring shapes from images which have been convolved with a re-circularizing PSF. We draw attention to a hitherto ignored noise related bias and show how this can be analyzed and corrected for. The analysis here draws heavily on the properties of real PSF's and we include as an appendix a brief review, highlighting those aspects which are relevant for weak lensing.

Nick Kaiser

1999-04-01T23:59:59.000Z

23

Gravitational lensing in metric theories of gravity  

Science Journals Connector (OSTI)

Gravitational lensing in metric theories of gravity is discussed. I introduce a generalized approximate metric element, inclusive of both post-post-Newtonian contributions and a gravitomagnetic field. Following Fermat’s principle and standard hypotheses, 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 gravitomagnetic correction offers the best perspectives for an observational detection. Actual measurements distinguish only marginally different metric theories from each other.

Mauro Sereno

2003-03-24T23:59:59.000Z

24

Morphology of gravitationally lensed galaxies  

Science Journals Connector (OSTI)

The compound optical system formed by the Hubble Space Telescope and a 200 kpc diameter gravitational objective lens provides an unprecedented view of a distant star forming galaxy in the UV. We describe a high resolution reconstruction of the UV image of the high redshift galaxy behind the z=0.4 cluster 0024+1654. Using a simultaneous parametric solution for the source morphology and the gravitational lens mass distribution we have found a robust unique solution for the source galaxy: all five arcs map back through the lens to give the same source-plane image. The reconstructed image of this forming galaxy has 7 milliarcsec pixels or 200 pc resolution in two rest-frame bands: 1800±200?Å and 3300±400?Å.

Tony Tyson; Greg Kochanski; Ian Dell’Antonio

1997-01-01T23:59:59.000Z

25

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

26

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

27

Biased Dark Energy Constraints from Neglecting Reduced Shear in Weak Lensing Surveys  

E-Print Network [OSTI]

The weak gravitational lensing of distant galaxies by large-scale structure is expected to become a powerful probe of dark energy. By measuring the ellipticities of large numbers of background galaxies, the subtle gravitational distortion called "cosmic shear" can be measured and used to constrain dark energy parameters. The observed galaxy ellipticities, however, are induced not by shear but by reduced shear, which also accounts for slight magnifications of the images. This distinction is negligible for present weak lensing surveys, but it will become more important as we improve our ability to measure and understand small-angle cosmic shear modes. I calculate the discrepancy between shear and reduced shear in the context of power spectra and cross spectra, finding the difference could be as high as 10% on the smallest accessible angular scales. I estimate how this difference will bias dark energy parameters obtained from two weak lensing methods: weak lensing tomography and the shear ratio method known as offset-linear scaling. For weak lensing tomography, ignoring the effects of reduced shear will cause future surveys considered by the Dark Energy Task Force to measure dark energy parameters that are biased by amounts comparable to their error bars. I advocate that reduced shear be properly accounted for in such surveys, and I provide a semi-analytic formula for doing so. Since reduced shear cross spectra do not follow an offset-linear scaling relation, the shear ratio method is similarly biased but with smaller significance.

Charles Shapiro

2008-12-03T23:59:59.000Z

28

Analytical Kerr black hole lensing in the weak deflection limit  

Science Journals Connector (OSTI)

We present an analytical treatment of gravitational lensing by a Kerr black hole in the weak deflection limit. Lightlike geodesics are expanded as a Taylor series up to and including third-order terms in m/b and a/b, where m is the black hole mass, a the angular momentum, and b the impact parameter of the light ray. Positions and magnifications of individual images are computed with a perturbative analysis. At this order, the degeneracy with the translated Schwarzschild lens is broken. The critical curve is still a circle displaced from the black hole position in the equatorial direction and the corresponding caustic is pointlike. The degeneracy between the black hole spin and its inclination relative to the observer is broken through the angular coordinates of the perturbed images.

Mauro Sereno and Fabiana De Luca

2006-12-21T23:59:59.000Z

29

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

30

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

31

Influence of the cosmological constant on gravitational lensing in small systems  

SciTech Connect (OSTI)

The cosmological constant {lambda} affects gravitational lensing phenomena. The contribution of {lambda} to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study of the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Because of {lambda} the unresolved images are slightly demagnified, the radius of the Einstein ring decreases, and the time delay increases. The effect is however negligible for near lenses. In the case of a null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.

Sereno, Mauro [Institut fuer Theoretische Physik, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)

2008-02-15T23:59:59.000Z

32

Influence of the cosmological constant on gravitational lensing in small systems  

Science Journals Connector (OSTI)

The cosmological constant ? affects gravitational lensing phenomena. The contribution of ? to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study of the weak deflection limit of the equations of motion in the Schwarzschild–de Sitter metric. Because of ? the unresolved images are slightly demagnified, the radius of the Einstein ring decreases, and the time delay increases. The effect is however negligible for near lenses. In the case of a null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.

Mauro Sereno

2008-02-15T23:59:59.000Z

33

Imprints of dynamical dark energy on weak-lensing measurements  

Science Journals Connector (OSTI)

......Large Synoptic Survey Telescope...g. Joint Dark Energy Mission (JDEM...galaxy redshift surveys and the abundance...spectrum of dark energy P (k), as...to dynamical dark energy is potentially...weak-lensing surveys. The error......

Sirichai Chongchitnan; Lindsay King

2010-09-21T23:59:59.000Z

34

arXiv:0709.4029v1[astro-ph]26Sep2007 Self Calibration of Tomographic Weak Lensing for the Physics of Baryons to  

E-Print Network [OSTI]

such as the Dark Energy Survey (DES), the SuperNova/Acceleration Probe (SNAP), and the Large Synoptic Survey lensing surveys to constrain both the internal structures of halos and the properties of the dark energy- ing probes of dark energy is weak gravitational lens- ing. Forthcoming weak lensing surveys expect

Hu, Wayne

35

HerMES: CANDIDATE GRAVITATIONALLY LENSED GALAXIES AND LENSING STATISTICS AT SUBMILLIMETER WAVELENGTHS  

SciTech Connect (OSTI)

We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg{sup 2} of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 {+-} 0.04 deg{sup -2}. The selected sources have 500 {mu}m flux densities (S {sub 500}) greater than 100 mJy. Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems (70%), and the lensing status of the four remaining sources is undetermined. We also present a supplementary sample of 29 (0.31 {+-} 0.06 deg{sup -2}) gravitationally lensed SMG candidates with S {sub 500} = 80-100 mJy, which are expected to contain a higher fraction of interlopers than the primary candidates. The number counts of the candidate lensed galaxies are consistent with a simple statistical model of the lensing rate, which uses a foreground matter distribution, the intrinsic SMG number counts, and an assumed SMG redshift distribution. The model predicts that 32%-74% of our S {sub 500} {>=} 100 mJy candidates are strongly gravitationally lensed ({mu} {>=} 2), with the brightest sources being the most robust; this is consistent with the observational data. Our statistical model also predicts that, on average, lensed galaxies with S {sub 500} = 100 mJy are magnified by factors of {approx}9, with apparently brighter galaxies having progressively higher average magnification, due to the shape of the intrinsic number counts. 65% of the sources are expected to have intrinsic 500 {mu}m flux densities less than 30 mJy. Thus, samples of strongly gravitationally lensed SMGs, such as those presented here, probe below the nominal Herschel detection limit at 500 {mu}m. They are good targets for the detailed study of the physical conditions in distant dusty, star-forming galaxies, due to the lensing magnification, which can lead to spatial resolutions of {approx}0.''01 in the source plane.

Wardlow, Julie L.; Cooray, Asantha; De Bernardis, Francesco; Calanog, J. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)] [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Amblard, A. [NASA, Ames Research Center, Moffett Field, CA 94035 (United States)] [NASA, Ames Research Center, Moffett Field, CA 94035 (United States); Arumugam, V. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)] [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Aussel, H.; Bethermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France)] [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France); Baker, A. J. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd, Piscataway, NJ 08854 (United States)] [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd, Piscataway, NJ 08854 (United States); Blundell, R.; Bussmann, R. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bock, J.; Bridge, C.; Carpenter, J. M. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)] [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Boselli, A.; Buat, V.; Burgarella, D. [Laboratoire d'Astrophysique de Marseille-LAM, Universite Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France)] [Laboratoire d'Astrophysique de Marseille-LAM, Universite Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France); Cabrera-Lavers, A.; Castro-Rodriguez, N. [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)] [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Casey, C. M. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)] [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); and others

2013-01-01T23:59:59.000Z

36

PROBING PRIMORDIAL NON-GAUSSIANITY WITH WEAK-LENSING MINKOWSKI FUNCTIONALS  

SciTech Connect (OSTI)

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

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

2012-11-20T23:59:59.000Z

37

Non-linear relativistic contributions to the cosmological weak-lensing convergence  

E-Print Network [OSTI]

Relativistic contributions to the dynamics of structure formation come in a variety of forms, and can potentially give corrections to the standard picture on typical scales of 100 Mpc. These corrections cannot be obtained by Newtonian numerical simulations, so it is important to accurately estimate the magnitude of these relativistic effects. Density fluctuations couple to produce a background of gravitational waves, which is larger than any primordial background. A similar interaction produces a much larger spectrum of vector modes which represent the frame-dragging rotation of spacetime. These can change the metric at the percent level in the concordance model at scales below the equality scale. Vector modes modify the lensing of background galaxies by large-scale structure. This gives in principle the exciting possibility of measuring relativistic frame dragging effects on cosmological scales. The effects of the non-linear tensor and vector modes on the cosmic convergence are computed and compared to first-order lensing contributions from density fluctuations, Doppler lensing, and smaller Sachs-Wolfe effects. The lensing from gravitational waves is negligible so we concentrate on the vector modes. We show the relative importance of this for future surveys such as Euclid and SKA. We find that these non-linear effects only marginally affect the overall weak lensing signal so they can safely be neglected in most analyses, though are still much larger than the linear Sachs-Wolfe terms. The second-order vector contribution can dominate the first-order Doppler lensing term at moderate redshifts and are actually more important for survey geometries like the SKA.

Sambatra Andrianomena; Chris Clarkson; Prina Patel; Obinna Umeh; Jean-Philippe Uzan

2014-02-18T23:59:59.000Z

38

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

39

The impact of cosmic variance on simulating weak lensing surveys  

E-Print Network [OSTI]

Upcoming weak lensing surveys will survey large cosmological volumes to measure the growth of cosmological structure with time and thereby constrain dark energy. One major systematic uncertainty in this process is the calibration of the weak lensing shape distortions, or shears. Most upcoming surveys plan to test several aspects of their shear estimation algorithms using sophisticated image simulations that include realistic galaxy populations based on high-resolution data from the Hubble Space Telescope (HST). However, existing datasets from the (HST) cover very small cosmological volumes, so cosmic variance could cause the galaxy populations in them to be atypical. A narrow redshift slice from such surveys could be dominated by a single large overdensity or underdensity. In that case, the morphology-density relation could alter the local galaxy populations and yield an incorrect calibration of shear estimates as a function of redshift. We directly test this scenario using the COSMOS survey, the largest-area...

Kannawadi, Arun; Lackner, Claire

2014-01-01T23:59:59.000Z

40

Gravitational Faraday rotation in a weak gravitational field  

Science Journals Connector (OSTI)

We examine the rotation of the plane of polarization for linearly polarized light rays by the weak gravitational field of an isolated physical system. Based on the rotation of inertial frames, we review the general integral expression for the net rotation. We apply this formula, an analogue to the usual electromagnetic Faraday effect, to some interesting astrophysical systems, namely uniformly shifting mass monopoles and a spinning external shell.

Mauro Sereno

2004-04-08T23:59:59.000Z

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

Gravitational Faraday rotation in a weak gravitational field  

E-Print Network [OSTI]

We examine the rotation of the plane of polarization for linearly polarized light rays by the weak gravitational field of an isolated physical system. Based on the rotation of inertial frames, we review the general integral expression for the net rotation. We apply this formula, analogue to the usual electromagnetic Faraday effect, to some interesting astrophysical systems: uniformly shifting mass monopoles and a spinning external shell.

Mauro Sereno

2004-01-15T23:59:59.000Z

42

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

43

Gravitational Lensing Accuracy Testing 2010 (GREAT10) Challenge Handbook  

E-Print Network [OSTI]

GRavitational lEnsing Accuracy Testing 2010 (GREAT10) is a public image analysis challenge aimed at the development of algorithms to analyse astronomical images. Specifically the challenge is to measure varying image distortions in the presence of a variable convolution kernel, pixelization and noise. This is the second in a series of challenges set to the astronomy, computer science and statistics communities, providing a structured environment in which methods can be improved and tested in preparation for planned astronomical surveys. GREAT10 extends upon previous work by introducing variable fields into the challenge. The 'Galaxy Challenge' involves the precise measurement of galaxy shape distortions, quantified locally by two parameters called shear, in the presence of a known convolution kernel. Crucially, the convolution kernel and the simulated gravitational lensing shape distortion both now vary as a function of position within the images, as is the case for real data. In addition we introduce the 'St...

Kitching, Thomas; Gill, Mandeep; Harmeling, Stefan; Heymans, Catherine; Massey, Richard; Rowe, Barnaby; Schrabback, Tim; Voigt, Lisa; Balan, Sreekumar; Bernstein, Gary; Bethge, Matthias; Bridle, Sarah; Courbin, Frederic; Gentile, Marc; Heavens, Alan; Hirsch, Michael; Hosseini, Reshad; Kiessling, Alina; Kirk, Donnacha; Kuijken, Konrad; Mandelbaum, Rachel; Moghaddam, Baback; Nurbaeva, Guldariya; Paulin-Henriksson, Stephane; Rassat, Anais; Rhodes, Jason; Schölkopf, Bernhard; Shawe-Taylor, John; Shmakova, Marina; Taylor, Andy; Velander, Malin; van Waerbeke, Ludovic; Witherick, Dugan; Wittman, David

2010-01-01T23:59:59.000Z

44

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

45

Testing the DGP model with gravitational lensing statistics  

E-Print Network [OSTI]

The self-accelerating braneworld model (DGP) seems to provide a simple alternative to the the standard $\\Lambda$CDM cosmology to explain the current cosmic acceleration, which is strongly indicated by measurements of Type Ia supernovae, as well as other concordant observations. In this work, we investigate observational constraints on this scenario from gravitational lensing statistics using the Cosmic Lens All-Sky Survey (CLASS) lensing sample. We show that a large parameter space of the DGP model is in good agreement with this radio source gravitational lensing sample. In the flat case, $\\Omega_\\mathrm{K}=0$, the likelihood is maximized, ${\\cal L}={\\cal L_\\mathrm{max}}$, for $\\1 = 0.30_{-0.11}^{+0.19}$. If we relax the prior on $\\Omega_\\mathrm{K}$, the likelihood peaks at $\\{\\1,\\2 \\} \\simeq \\{0.29, 0.12\\}$, just slightly in the region of open models. However the confidence contours are pretty elongated so that we can not discard either close or flat or open models

Zong-Hong Zhu; Mauro Sereno

2008-04-17T23:59:59.000Z

46

Gravitationally lensed image simulations for the study of the substructure in galaxy clusters  

E-Print Network [OSTI]

As gravitational lensing is susceptible to all gravitating matter-both baryonic and dark-it provides a potentially clean way to study the mass distribution of galaxy clusters. We are particularly interested in the substructure ...

Peeples, Molly S

2005-01-01T23:59:59.000Z

47

Breaking the Disk/Halo Degeneracy with Gravitational Lensing  

E-Print Network [OSTI]

The degeneracy between the disk and the dark matter contribution to galaxy rotation curves remains an important uncertainty in our understanding of disk galaxies. Here we discuss a new method for breaking this degeneracy using gravitational lensing by spiral galaxies, and apply this method to the spiral lens B1600+434 as an example. The combined image and lens photometry constraints allow models for B1600+434 with either a nearly singular dark matter halo, or a halo with a sizable core. A maximum disk model is ruled out with high confidence. Further information, such as the circular velocity of this galaxy, will help break the degeneracies. Future studies of spiral galaxy lenses will be able to determine the relative contribution of disk, bulge, and halo to the mass in the inner parts of galaxies.

Ariyeh H. Maller; Luc Simard; Puragra Guhathakurta; Jens Hjorth; Andreas O. Jaunsen; Ricardo A. Flores; Joel R. Primack

1999-10-12T23:59:59.000Z

48

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

49

THE WEIGHT OF EMPTINESS: THE GRAVITATIONAL LENSING SIGNAL OF STACKED VOIDS  

SciTech Connect (OSTI)

The upcoming new generation of spectroscopic galaxy redshift surveys will provide large samples of cosmic voids, large distinct, underdense structures in the universe. Combining these with future galaxy imaging surveys, we study the prospects of probing the underlying matter distribution in and around cosmic voids via the weak gravitational lensing effects of stacked voids, utilizing both shear and magnification information. The statistical precision is greatly improved by stacking a large number of voids along different lines of sight, even when taking into account the impact of inherent miscentering and projection effects. We show that Dark Energy Task Force Stage IV surveys, such as the Euclid satellite and the Large Synoptic Survey Telescope, should be able to detect the void lensing signal with sufficient precision from stacking abundant medium-sized voids, thus providing direct constraints on the matter density profile of voids independent of assumptions on galaxy bias.

Krause, Elisabeth; Dore, Olivier [Department of Astrophysics, Caltech, MC 249-17, Pasadena, CA 91125 (United States); Chang, Tzu-Ching; Umetsu, Keiichi [IAA, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)

2013-01-10T23:59:59.000Z

50

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

51

Constraints on early dark energy from CMB lensing and weak lensing tomography  

SciTech Connect (OSTI)

Dark energy can be studied by its influence on the expansion of the Universe as well as on the growth history of the large-scale structure. In this paper, we follow the growth of the cosmic density field in early dark energy cosmologies by combining observations of the primary CMB temperature and polarisation power spectra at high redshift, of the CMB lensing deflection field at intermediate redshift and of weak cosmic shear at low redshifts for constraining the allowed amount of early dark energy. We present these forecasts using the Fisher matrix formalism and consider the combination of Planck data with the weak lensing survey of Euclid. We find that combining these data sets gives powerful constraints on early dark energy and is able to break degeneracies in the parameter set inherent to the various observational channels. The derived statistical 1{sigma}-bound on the early dark energy density parameter is {sigma}({Omega}{sup e}{sub d}) = 0.0022 which suggests that early dark energy models can be well examined in our approach. In addition, we derive the dark energy figure of merit for the considered dark energy parameterisation and comment on the applicability of the growth index to early dark energy cosmologies.

Hollenstein, Lukas; Crittenden, Robert [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom)] [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Sapone, Domenico [Departement de Physique Theorique, Universite de Geneve, 24 Quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland)] [Departement de Physique Theorique, Universite de Geneve, 24 Quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland); Schaefer, Bjoern Malte, E-mail: lukas.hollenstein@port.ac.uk, E-mail: domenico.sapone@unige.ch, E-mail: robert.crittenden@port.ac.uk, E-mail: spirou@ita.uni-heidelberg.de [Astronomisches Recheninstitut, Zentrum fuer Astronomie, Universitaet Heidelberg, Moenchhofstrasse 12, 69120 Heidelberg (Germany)

2009-04-15T23:59:59.000Z

52

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

53

A Bayesian Analysis of Regularised Source Inversions in Gravitational Lensing  

SciTech Connect (OSTI)

Strong gravitational lens systems with extended sources are of special interest because they provide additional constraints on the models of the lens systems. To use a gravitational lens system for measuring the Hubble constant, one would need to determine the lens potential and the source intensity distribution simultaneously. A linear inversion method to reconstruct a pixellated source distribution of a given lens potential model was introduced by Warren and Dye. In the inversion process, a regularization on the source intensity is often needed to ensure a successful inversion with a faithful resulting source. In this paper, we use Bayesian analysis to determine the optimal regularization constant (strength of regularization) of a given form of regularization and to objectively choose the optimal form of regularization given a selection of regularizations. We consider and compare quantitatively three different forms of regularization previously described in the literature for source inversions in gravitational lensing: zeroth-order, gradient and curvature. We use simulated data with the exact lens potential to demonstrate the method. We find that the preferred form of regularization depends on the nature of the source distribution.

Suyu, Sherry H.; /Caltech /KIPAC, Menlo Park; Marshall, P.J.; /KIPAC, Menlo Park; Hobson, M.P.; /Cambridge U., Inst. of Astron.; Blandford, R.D.; /Caltech /KIPAC, Menlo

2006-01-25T23:59:59.000Z

54

Cosmology with the cluster mass function: mass estimators and shape systematics in large weak lensing surveys  

Science Journals Connector (OSTI)

......density, and the nature and evolution of dark energy. Large weak lensing surveys of 20 000 galaxy clusters and groups will...Joint Dark Energy Mission, Large Synoptic Survey Teloscope and Dark Energy Survey unhindered by galaxy cluster and group......

Virginia L. Corless; Lindsay J. King

2009-06-11T23:59:59.000Z

55

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

56

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

57

3D Weak Gravitational Lensing of the CMB and Galaxies  

E-Print Network [OSTI]

In this paper we present a power spectrum formalism that combines the full three-dimensional information from the galaxy ellipticity field, with information from the cosmic microwave background (CMB). We include in this approach galaxy cosmic shear and galaxy intrinsic alignments, CMB deflection, CMB temperature and CMB polarisation data; including the inter-datum power spectra between all quantities. We apply this to forecasting cosmological parameter errors for CMB and imaging surveys and show that the additional covariance between the CMB and ellipticity measurements can improve galaxy intrinsic alignment measurements by a factor of two, and dark energy equation of state measurements by thirty percent. We present predictions for Euclid-like, KiDS, ACTPoL, and CoRE-like experiments and show that the combination of cosmic shear and the CMB, from Euclid-like and CoRE-like experiments, can measure the sum of neutrino masses with an error of 0.02 eV, and the dark energy equation of state with an error on w0 of ...

Kitching, T D; Das, S

2014-01-01T23:59:59.000Z

58

Self-gravitating line sources of weak hypercharge  

E-Print Network [OSTI]

We explore the role of the Cremmer-Scherk mechanism in the context of low energy effective string theory by coupling the antisymmetric 3-form gauge potential to an Abelian gauge potential carrying weak hypercharge. The theory admits a class of exact self-gravitating solutions in the spontaneously broken phase in which the dual fields acquire massive perturbative modes. Despite the massive nature of these fields they admit non-perturbative progressive longitudinal modes that together with pp-type gravitational waves travel in a direction of a line source at the speed of light.

T. Dereli; R. W. Tucker

1999-02-19T23:59:59.000Z

59

Nonsingular density profiles of dark matter halos and Strong gravitational lensing  

E-Print Network [OSTI]

We use the statistics of strong gravitational lenses to investigate whether mass profiles with a flat density core are supported. The probability for lensing by halos modeled by a nonsingular truncated isothermal sphere (NTIS) with image separations greater than a certain value (ranging from zero to ten arcseconds) is calculated. NTIS is an analytical model for the postcollapse equilibrium structure of virialized objects derived by Shapiro, Iliev & Raga. This profile has a soft core and matches quite well with the mass profiles of dark matter-dominated dwarf galaxies deduced from their observed rotation curves. It also agrees well with the NFW (Navarro-Frenk-White) profile at all radii outside of a few NTIS core radii. Unfortunately, comparing the results with those for singular lensing halos (NFW and SIS+NFW) and strong lensing observations, the probabilities for lensing by NTIS halos are far too low. As this result is valid for any other nonsingular density profiles (with a large core radius), we conclude that nonsingular density profiles (with a large core radius) for CDM halos are ruled out by statistics of strong gravitational lenses.

Da-Ming Chen

2005-02-05T23:59:59.000Z

60

Distinguishing GR and f(R) gravity with the gravitational lensing Minkowski Functionals  

E-Print Network [OSTI]

We explore the Minkowski Functionals of weak lensing convergence map to distinguish between f(R) gravity and the General Relativity (GR). The mock weak lensing convergence maps are constructed with a set of high-resolution simulations assuming different gravity models. It is shown that the lensing MFs of f(R) gravity can be considerably different from that of GR because of the environmentally dependent enhancement of structure formation. We also investigate the effect of lensing noise on our results, and find that it is likely to distinguish F5, F6 and GR gravity models with a galaxy survey of ~3000degree^2 and with a background source number density of n_g=30arcmin^(-2), comparable to an upcoming survey Dark Energy survey (DES).

Chenxiaoji, Ling; Ra, Li; Baojiu, Li; Jie, Wang; Liang, Gao

2014-01-01T23:59:59.000Z

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61

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

62

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

63

The impact of camera optical alignments on weak lensing measures for the Dark Energy Survey  

Science Journals Connector (OSTI)

......weak lensing measures for the Dark Energy Survey Michelle L. Antonik 1 David...with specific reference to the Dark Energy Survey (DES). We compute optics...Suprime-Cam (HSC) survey 1 and the Dark Energy Survey: DES 2 ), telescopes under......

Michelle L. Antonik; David J. Bacon; Sarah Bridle; Peter Doel; David Brooks; Sue Worswick; Gary Bernstein; Rebecca Bernstein; Darren DePoy; Brenna Flaugher; Joshua A. Frieman; Michael Gladders; Gaston Gutierrez; Bhuvnesh Jain; Michael Jarvis; Stephen M. Kent; Ofer Lahav; S.-J. Parker; Aaron Roodman; Alistair R. Walker

2013-01-01T23:59:59.000Z

64

Weak lensing predictions for coupled dark energy cosmologies at non-linear scales  

Science Journals Connector (OSTI)

......models, for forthcoming ground-based [such as Dark Energy Survey (DES)] and space-based (Euclid) weak...lensing (WL) surveys - both a ground-based survey similar to the Dark Energy Survey (DES)1 and a space-based survey, i.e......

Emma Beynon; Marco Baldi; David J. Bacon; Kazuya Koyama; Cristiano Sabiu

2012-06-01T23:59:59.000Z

65

Weak lensing and dark energy: The impact of dark energy on nonlinear dark matter clustering  

SciTech Connect (OSTI)

We examine the influence of percent-level dark energy corrections to the nonlinear matter power spectrum on constraints of the dark energy equation of state from future weak lensing probes. We explicitly show that a poor approximation (off by > or approx.10%) to the nonlinear corrections causes a > or approx. 1{sigma} bias on the determination of the dark energy equation of state. Future weak lensing surveys must therefore incorporate dark energy modifications to the nonlinear matter power spectrum accurate to the percent-level, to avoid introducing significant bias in their measurements. For the WMAP5 cosmology, the more accurate power spectrum is more sensitive to dark energy properties, resulting in a factor of 2 improvement in dark energy equation of state constraints. We explore the complementary constraints on dark energy from future weak lensing and supernova surveys. A space-based, Joint Dark Energy Mission-like survey measures the equation of state in five independent redshift bins to {approx}10%, while this improves to {approx}5% for a wide-field ground-based survey like the Large Synoptic Survey Telescope. These constraints are contingent upon our ability to control weak lensing systematic uncertainties to the sub-percent level.

Joudaki, Shahab; Cooray, Asantha; Holz, Daniel E. [Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2009-07-15T23:59:59.000Z

66

Weak lensing and dark energy: The impact of dark energy on nonlinear dark matter clustering  

Science Journals Connector (OSTI)

We examine the influence of percent-level dark energy corrections to the nonlinear matter power spectrum on constraints of the dark energy equation of state from future weak lensing probes. We explicitly show that a poor approximation (off by ?10%) to the nonlinear corrections causes a ?1? bias on the determination of the dark energy equation of state. Future weak lensing surveys must therefore incorporate dark energy modifications to the nonlinear matter power spectrum accurate to the percent-level, to avoid introducing significant bias in their measurements. For the WMAP5 cosmology, the more accurate power spectrum is more sensitive to dark energy properties, resulting in a factor of 2 improvement in dark energy equation of state constraints. We explore the complementary constraints on dark energy from future weak lensing and supernova surveys. A space-based, Joint Dark Energy Mission-like survey measures the equation of state in five independent redshift bins to ?10%, while this improves to ?5% for a wide-field ground-based survey like the Large Synoptic Survey Telescope. These constraints are contingent upon our ability to control weak lensing systematic uncertainties to the sub-percent level.

Shahab Joudaki; Asantha Cooray; Daniel E. Holz

2009-07-08T23:59:59.000Z

67

Combining weak lensing tomography with halo clustering to probe dark energy  

Science Journals Connector (OSTI)

Two methods of constraining the properties of dark energy are weak lensing tomography and cluster counting. Uncertainties in mass calibration of clusters can be reduced by using the properties of halo clustering (the clustering of clusters). However, within a single survey, weak lensing and halo clustering probe the same density fluctuations. We explore the question of whether this information can be used twice—once in weak lensing and then again in halo clustering to calibrate cluster masses—or whether the combined dark energy constraints are weaker than the sum of the individual constraints. For a survey like the Dark Energy Survey (DES), we find that the cosmic shearing of source galaxies at high redshifts is indeed highly correlated with halo clustering at lower redshifts. Surprisingly, this correlation does not degrade cosmological constraints for a DES-like survey, and in fact, constraints are marginally improved since the correlations themselves act as additional observables. This considerably simplifies the analysis for a DES-like survey: when weak lensing and halo clustering are treated as independent experiments, the combined dark energy constraints (cluster counts included) are accurate if not slightly conservative. Our findings mirror those of Takada and Bridle, who investigated correlations between the cosmic shear and cluster counts.

Charles Shapiro and Scott Dodelson

2007-10-18T23:59:59.000Z

68

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

69

Electroweak Corrections to Photon Scattering, Polarization and Lensing in a Gravitational Background and the Near Horizon Limit  

E-Print Network [OSTI]

We investigate the semiclassical approach to the lensing of photons in a spherically symmetric gravitational background, starting from Born level and include in our analysis the radiative corrections obtained from the electroweak theory for the graviton/photon/photon vertex. In this approach, the cross section is related to the angular variation of the impact parameter ($b$), which is then solved for $b$ as a function of the angle of deflection, and measured in horizon units ($b_h\\equiv b/(2 G M)$). Exact numerical solutions for the angular deflection are presented. The numerical analysis shows that perturbation theory in a weak background agrees with the classical Einstein formula for the deflection already at distances of the order of $20$ horizon units ($\\sim 20\\, b_h$) and it is optimal in the description both of very strong and weak lensings. We show that the electroweak corrections to the cross section are sizeable, becoming very significant for high energy gamma rays. Our analysis covers in energy most of the photon spectrum, from the cosmic microwave background up to very high energy gamma rays, and scatterings with any value of the photon impact parameter. We also study the helicity-flip photon amplitude, which is of $O(\\alpha^2)$ in the weak coupling $\\alpha$, and its massless fermion limit, which involves the exchange of a conformal anomaly pole. The corresponding cross section is proportional to the Born level result and brings to a simple renormalization of Einsten's formula.

Claudio Coriano; Luigi Delle Rose; Matteo Maria Maglio; Mirko Serino

2014-11-11T23:59:59.000Z

70

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

71

Electroweak Corrections to Photon Scattering, Polarization and Lensing in a Gravitational Background and the Near Horizon Limit  

E-Print Network [OSTI]

We investigate the semiclassical approach to the lensing of photons in a spherically symmetric gravitational background, starting from Born level and include in our analysis the radiative corrections obtained from the electroweak theory for the graviton/photon/photon vertex. In this approach, the cross section is related to the angular variation of the impact parameter ($b$), which is then solved for $b$ as a function of the angle of deflection, and measured in horizon units ($b_h\\equiv b/(2 G M)$). Exact numerical solutions for the angular deflection are presented. The numerical analysis shows that perturbation theory in a weak background agrees with the classical Einstein formula for the deflection already at distances of the order of $20$ horizon units ($\\sim 20\\, b_h$) and it is optimal in the description both of very strong and weak lensings. We show that the electroweak corrections to the cross section are sizeable, becoming very significant for high energy gamma rays. Our analysis covers in energy most...

Coriano, Claudio; Maglio, Matteo Maria; Serino, Mirko

2014-01-01T23:59:59.000Z

72

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

73

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

SciTech Connect (OSTI)

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

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

2012-04-01T23:59:59.000Z

74

Strong Gravitational Lensing Time Delay Statistics and the Density Profile of Dark Halos  

Science Journals Connector (OSTI)

The distribution of differential time delays ?t between images produced by strong gravitational lensing contains information on the mass distributions in the lensing objects as well as on cosmological parameters such as H0. We derive an explicit expression for the conditional probability distribution function of time delays P(?t | ?), given an image separation between multiple images ? and related statistics. We consider lensing halos described by the singular isothermal sphere (SIS) approximation and by its generalization as proposed by Navarro, Frenk, & White (NFW), which has a density profile ? ? r-? in the innermost region. The time delay distribution is very sensitive to these profiles; steeper inner slopes tend to produce larger time delays. For example, if H0 = 70 km s-1 Mpc-1, a ?-dominated cosmology and a source redshift zS = 1.27 are assumed, lenses with ? = 5'' produce a time delay of ?t = 1.5, 0.39, 0.15, and 0.071 yr (50% confidence interval) for SIS, generalized NFW with ? = 1.5, ? = 1.0, and ? = 0.5, respectively. At a fixed image separation, the time delay is determined by the difference in the lensing potential between the position of the two images, which typically occur at different impact parameters. Although the values of ?t are proportional to the inverse of H0, P(?t | ?) is rather insensitive to all other cosmological model parameters, source redshifts, magnification biases, and so on. A knowledge of P(?t | ?) will also be useful in designing the observing program of future large-scale synoptic variability surveys and for evaluating possible selection biases operating against large splitting lens systems.

Masamune Oguri; Atsushi Taruya; Yasushi Suto; Edwin L. Turner

2002-01-01T23:59:59.000Z

75

SDSS J131339.98+515128.3: A new GravitationallyLensed Quasar Selected Based on Near-infrared Excess  

SciTech Connect (OSTI)

We report the discovery of a new gravitationally lensed quasar, SDSS J131339.98+515128.3, at a redshift of 1:875 with an image separation of 1: 0024. The lensing galaxy is clearly detected in visible-light follow-up observations. We also identify three absorption-line doublets in the spectra of the lensed quasar images, from which we measure the lens redshift to be 0:194. Like several other known lenses, the lensed quasar images have different continuum slopes. This difference is probably the result of reddening and microlensing in the lensing galaxy. The lensed quasar was selected by correlating Sloan Digital Sky Survey (SDSS) spectroscopic quasars with Two Micron All Sky Survey (2MASS) sources and choosing quasars that show near-infrared (IR) excess. The near-IR excess can originate, for example, from the contribution of the lensing galaxy at near-IR wavelengths. We show that the near-IR excess technique is indeed an efficient method to identify lensed systems from a large sample of quasars.

Ofek, E.O.; Oguri, M.; Jackson, N.; Inada, N.; Kayo, I.

2007-09-28T23:59:59.000Z

76

Wide-Field Weak Lensing by RX J1347–1145  

Science Journals Connector (OSTI)

We present an analysis of weak-lensing observations for RX J1347-1145 over a 43' ? 43' field taken in B and R filters on the Blanco 4 m telescope at CTIO. RX J1347-1145 is a massive cluster at redshift z = 0.45. Using a population of galaxies with 20 R p v = 1400 km s-1 for a singular isothermal sphere model and r200 = 3.5 Mpc with c = 15 for an NFW model in an ?m = 0.3, ?? = 0.7 cosmology. In addition, a mass-to-light ratio M/LR = 90 ± 20 M?/LR? was determined. These values are consistent with the previous weak-lensing study of RX J1347-1145 by Fischer & Tyson, giving strong evidence that systemic bias was not introduced by the relatively small field of view in that study. Our best-fit parameter values are also consistent with recent X-ray studies by Allen et al. and Ettori et al. but are not consistent with recent optical velocity dispersion measurements by Cohen & Kneib.

Thomas P. Kling; Ian Dell'Antonio; David Wittman; J. Anthony Tyson

2005-01-01T23:59:59.000Z

77

Constraining dark energy evolution with gravitational lensing by large scale structures  

Science Journals Connector (OSTI)

We study the sensitivity of weak lensing by large scale structures as a probe of the evolution of dark energy. We explore a two-parameters model of dark energy evolution, inspired by tracking quintessence models. To this end, we compute the likelihood of a few fiducial models with varying and nonvarying equation of states. For the different models, we investigate the dark energy parameter degeneracies with the mass power spectrum shape ?, normalization ?8, and with the matter mean density ?M. We find that degeneracies are such that weak lensing turns out to be a good probe of dark energy evolution, even with limited knowledge on ?, ?8, and ?M. This result is a strong motivation for performing large scale structure simulations beyond the simple constant dark energy models, in order to calibrate the nonlinear regime accurately. Such calibration could then be used for any large scale structure tests of dark energy evolution. Prospective for the Canada France Hawaii Telescope Legacy Survey and Super-Novae Acceleration Probe are given. These results complement nicely the cosmic microwave background and supernovae constraints.

Karim Benabed and Ludovic Van Waerbeke

2004-12-09T23:59:59.000Z

78

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

79

A CLIPPING METHOD TO MITIGATE THE IMPACT OF CATASTROPHIC PHOTOMETRIC REDSHIFT ERRORS ON WEAK LENSING TOMOGRAPHY  

SciTech Connect (OSTI)

We use a mock catalog of galaxies based on the COSMOS galaxy catalog, including information on photometric redshift (photo-z) and spectral energy distribution types of galaxies, in order to study how to define a galaxy subsample suitable for weak lensing tomography feasible with optical (and near-IR) multi-band data. Since most useful cosmological information arises from the sample variance limited regime for upcoming lensing surveys, a suitable subsample can be obtained by discarding a large fraction of galaxies that have less reliable photo-z estimations. We develop a method to efficiently identify photo-z outliers by monitoring the width of the posterior likelihood function of redshift estimation for each galaxy. This clipping method may allow us to obtain clean tomographic redshift bins (here three bins are considered) that have almost no overlap, by discarding more than {approx}70% of galaxies with ill-defined photo-zs corresponding to the number densities of remaining galaxies less than {approx}20 arcmin{sup -2} for a Subaru-type deep survey. Restricting the ranges of magnitudes and redshifts and/or adding near-IR data help us obtain a cleaner redshift binning. Using the Fisher information matrix formalism, we propagate photo-z errors into biases in the dark energy equation of state parameter w. We find that, by discarding most of the ill-defined photo-z galaxies, the bias in w can be reduced to a level comparable to the marginalized statistical error; however, the residual small systematic bias remains due to asymmetric scatters around the relation between photometric and true redshifts. We also use the mock catalog to estimate the cumulative signal-to-noise ratios (S/Ns) for measuring the angular cross-correlations of galaxies between finer photo-z bins, finding higher S/N values for the bins that include photo-z outliers.

Nishizawa, Atsushi J. [Astronomical Institute, Tohoku University, Aramaki Aobaku, Sendai 980-8578 (Japan); Takada, Masahiro [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa City, Chiba 277-8582 (Japan); Hamana, Takashi; Furusawa, Hisanori, E-mail: nishizawa@astr.tohoku.ac.j [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka City, Tokyo 181-8588 (Japan)

2010-08-01T23:59:59.000Z

80

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

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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81

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

82

Bayesian Galaxy Shape Measurement for Weak Lensing Surveys -II. Application to Simulations  

E-Print Network [OSTI]

We extend the Bayesian model fitting shape measurement method presented in Miller et al. (2007) and use the method to estimate the shear from the Shear TEsting Programme simulations (STEP). The method uses a fast model fitting algorithm which uses realistic galaxy profiles and analytically marginalises over the position and amplitude of the model by doing the model fitting in Fourier space. This is used to find the full posterior probability in ellipticity so that the shear can be estimated in a fully Bayesian way. The Bayesian shear estimation allows measurement bias arising from the presence of random noise to be removed. In this paper we introduce an iterative algorithm that can be used to estimate the intrinsic ellipticity prior and show that this is accurate and stable. By using the method to estimate the shear from the STEP1 simulations we find the method to have a shear bias of m ~ 0.005 and a variation in shear offset with PSF type of sigma_c ~ 0.0002. These values are smaller than for any method presented in the STEP1 publication that behaves linearly with shear. Using the method to estimate the shear from the STEP2 simulations we find than the shear bias and offset are m ~ 0.002 and c ~ -0.0007 respectively. In addition we find that the bias and offset are stable to changes in magnitude and size of the galaxies. Such biases should yield any cosmological constraints from future weak lensing surveys robust to systematic effects in shape measurement.

T. D. Kitching; L. Miller; C. E. Heymans; L. van Waerbeke; A. F. Heavens

2008-02-12T23:59:59.000Z

83

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

84

Gravitational Lensing & Stellar Dynamics: Dark-Matter and Baryons in Early-type Galaxies to z=1  

E-Print Network [OSTI]

Gravitational lensing and stellar dynamics provide two complementary, nearly orthogonal, constraints on the mass distribution of early-type lens galaxies. This allows the luminous and dark-matter distribution in higher-redshift (z>0.1) galaxies to be studied beyond the limitations of each individual method. Two surveys have been initiated to compile a large sample of early-type galaxies suitable to lensing and dynamical studies: (1) The Lenses Structure & Dynamics (LSD) Survey and (2) the Sloan Lens ACS (SLACS) Survey. Using spherically symmetric mass models, I illustrated how lensing and dynamical constraints can be used to measure the ``effective'' density slope (gamma') of galaxies inside their Einstein radii and estimate the typical error on this determination. The main results from the LSD survey thus far are: (i) Massive (typically >L_*) early-type galaxies at z=0.5-1 contain a significant fraction f_CDM=0.4-0.7 of dark matter inside their Einstein radii. [The null-hypothesis, f_CDM=0, is excluded at the >99% in all analyzed systems.] (ii) The inner CDM density slope is gamma_CDM=1.3^{+0.2}_{-0.3} (68% CL). (iii) The total density slope gamma' = 1.9 +- 0.1 (with 0.3 rms scatter in the sample). The intrinsic scatter of 15% in gamma' is consistent with local dynamical studies and can lead to a 30% rms scatter in inferred values of H_0 from lens time-delays, when purely isothermal mass models are assumed. Hence, the common practice to assume that lens galaxies are perfectly isothermal should be abandoned, especially in cases where this assumption is critical.

L. V. E. Koopmans

2004-12-22T23:59:59.000Z

85

Neutrino masses, dark energy and the gravitational lensing of pre-galactic H I  

Science Journals Connector (OSTI)

......Large Synoptic Survey Telescope,2 PanSTARRS,3 Dark Energy Survey4; Hannestad...ability of these surveys to measure properties of the dark energy (Hannestad...the lensing surveys by themselves...Fig. 3, the dark energy equation of......

R. Benton Metcalf

2010-01-21T23:59:59.000Z

86

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

87

Higher-order convergence statistics for three-dimensional weak gravitational lensing  

Science Journals Connector (OSTI)

......statistics are useful to lift degeneracies, allowing...difficult than two-point as they can be dominated...focus on three- and four-point statistics...Three-point correlation Four-point correlation Basis...is to express the four-point correlation function......

Dipak Munshi; Alan Heavens; Peter Coles

2011-03-11T23:59:59.000Z

88

Cosmology with Doppler Lensing  

E-Print Network [OSTI]

Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts. This effect dominates over the usual gravitational lensing magnification at low redshift. Doppler lensing is a promising new probe of cosmology, and we explore in detail how to utilize the effect with forthcoming surveys. We present cosmological simulations of the Doppler and gravitational lensing effects based on the Millennium simulation. We show that Doppler lensing can be detected around stacked voids or unvirialised over-densities. New power spectra and correlation functions are proposed which are designed to be sensitive to Doppler lensing. We consider the impact of gravitational lensing and intrinsic size correlations on these quantities. We compute the correlation functions and forecast the errors for realistic forthcoming surveys, providing predictions for constraints...

Bacon, David J; Clarkson, Chris; Bolejko, Krzysztof; Maartens, Roy

2014-01-01T23:59:59.000Z

89

Gravitational lensing: a unique probe of dark matter and dark energy  

Science Journals Connector (OSTI)

...fine-scale distribution of dark matter will require exquisite...puzzle of resolving the dark matter question were...astronomers, consider the discovery from two studies of distant...gravitating matter (dark and visible), but actually...implies the presence of an energy density with a negative...

2010-01-01T23:59:59.000Z

90

Gravitational lensing: a unique probe of dark matter and dark energy  

Science Journals Connector (OSTI)

...gravitating matter (dark and visible...in subsequent surveys (e.g. Astier...presence of an energy density with...The moniker dark energy was invented...Digital Sky Survey commissioning...the hunt for dark matter and dark energy in the UniverseNew...

2010-01-01T23:59:59.000Z

91

Higgs Gravitational Interaction, Weak Boson Scattering, and Higgs Inflation in Jordan and Einstein Frames  

E-Print Network [OSTI]

We study gravitational interaction of Higgs boson through the unique dimension-4 operator $\\xi H^\\dag H R$, with $H$ the Higgs doublet and $R$ the Ricci scalar curvature. We analyze the effect of this dimensionless nonminimal coupling $\\xi$ on weak gauge boson scattering in both Jordan and Einstein frames. We explicitly establish the longitudinal-Goldstone boson equivalence theorem with nonzero $\\xi$ coupling in both frames, and analyze the unitarity constraints. We study the $\\xi$-induced weak boson scattering cross sections at O(1-30)TeV scales, and propose to probe the Higgs-gravity coupling via weak boson scattering experiments at the LHC(14TeV) and the next generation pp colliders (50-100TeV). We further extend our study to Higgs inflation, and quantitatively derive the perturbative unitarity bounds via coupled channel analysis, under large field background at the inflation scale. We analyze the unitarity constraints on the parameter space in both the conventional Higgs inflation and the improved models in light of the recent BICEP2 data.

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

2014-04-17T23:59:59.000Z

92

Constraining dark energy by combining cluster counts and shear-shear correlations in a weak lensing survey  

Science Journals Connector (OSTI)

We study the potential of a large future weak lensing survey to constrain dark-energy properties by using both the number counts of detected galaxy clusters (sensitive primarily to density fluctuations on small scales) and tomographic shear-shear correlations (restricted to intermediate and large scales). We use the Fisher matrix formalism, assume a flat universe, and parametrize the equation of state of dark energy by w(a)=w0+wa(1-a), to forecast the expected statistical errors from either observable, and from their combination. We show that the covariance between these two observables is small, and argue that they can therefore be regarded as independent constraints. We find that, when the number counts and the shear-shear correlations (on angular scales ??1000) are combined, a LSST (Large Synoptic Survey Telescope)–like survey can yield statistical errors on ?DE, w0, wa as tight as 0.003, 0.03, 0.1. These values are a factor of 2–25 better than using either observable alone. The results are also about a factor of 2 better than those from combining number counts of galaxy clusters and their power spectrum.

Wenjuan Fang and Zoltán Haiman

2007-02-26T23:59:59.000Z

93

Constraining Dark Energy by Combining Cluster Counts and Shear-Shear Correlations in a Weak Lensing Survey  

E-Print Network [OSTI]

We study the potential of a large future weak-lensing survey to constrain dark energy properties by using both the number counts of detected galaxy clusters (sensitive primarily to density fluctuations on small scales) and tomographic shear-shear correlations (restricted to large scales). We use the Fisher matrix formalism, assume a flat universe and parameterize the equation of state of dark energy by w(a)=w_0+w_a(1-a), to forecast the expected statistical errors from either observable, and from their combination. We show that the covariance between these two observables is small, and argue that therefore they can be regarded as independent constraints. We find that when the number counts and the shear-shear correlations (on angular scales l Survey Telescope)-like survey can yield statistical errors on (Omega_DE, w_0, w_a) as tight as (0.003, 0.03, 0.1). These values are a factor of 2-25 better than using either observable alone. The results are also about a factor of two better than those from combining number counts of galaxy clusters and their power spectrum.

Wenjuan Fang; Zoltan Haiman

2006-12-07T23:59:59.000Z

94

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

95

Breakdown of the Equivalence between Energy Content and Weight in a Weak Gravitational Field for a Quantum Body  

E-Print Network [OSTI]

It is shown that weight operator of a composite quantum body in a weak external gravitational field in the post-Newtonian approximation of the General Relativity does not commute with its energy operator, taken in the absence of the field. Nevertheless, the weak equivalence between the expectations values of weight and energy is shown to survive at a macroscopic level for stationary quantum states for the simplest composite quantum body - a hydrogen atom. Breakdown of the weak equivalence between weight and energy at a microscopic level for stationary quantum states can be experimentally detected by studying unusual electromagnetic radiation, emitted by the atoms, supported and moved in the Earth gravitational field with constant velocity, using spacecraft or satellite. For superpositions of stationary quantum states, a breakdown of the above mentioned equivalence at a macroscopic level leads to time dependent oscillations of the expectation values of weight, where the equivalence restores after averaging over time procedure.

Andrei Lebed

2012-05-14T23:59:59.000Z

96

SDSS J2222+2745: A GRAVITATIONALLY LENSED SEXTUPLE QUASAR WITH A MAXIMUM IMAGE SEPARATION OF 15.''1 DISCOVERED IN THE SLOAN GIANT ARCS SURVEY  

SciTech Connect (OSTI)

We report the discovery of a unique gravitational lens system, SDSS J2222+2745, producing five spectroscopically confirmed images of a z{sub s} = 2.82 quasar lensed by a foreground galaxy cluster at z{sub l} = 0.49. We also present photometric and spectroscopic evidence for a sixth lensed image of the same quasar. The maximum separation between the quasar images is 15.''1. Both the large image separations and the high image multiplicity are in themselves rare among known lensed quasars, and observing the combination of these two factors is an exceptionally unlikely occurrence in present data sets. This is only the third known case of a quasar lensed by a cluster, and the only one with six images. The lens system was discovered in the course of the Sloan Giant Arcs Survey, in which we identify candidate lenses in the Sloan Digital Sky Survey and target these for follow-up and verification with the 2.56 m Nordic Optical Telescope. Multi-band photometry obtained over multiple epochs from 2011 September to 2012 September reveals significant variability at the {approx}10%-30% level in some of the quasar images, indicating that measurements of the relative time delay between quasar images will be feasible. In this lens system, we also identify a bright (g = 21.5) giant arc corresponding to a strongly lensed background galaxy at z{sub s} = 2.30. We fit parametric models of the lens system, constrained by the redshift and positions of the quasar images and the redshift and position of the giant arc. The predicted time delays between different pairs of quasar images range from {approx}100 days to {approx}6 yr.

Dahle, H.; Groeneboom, N. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Gladders, M. D.; Abramson, L. E. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States); Sharon, K. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Bayliss, M. B. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wuyts, E. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbackstrasse 1, D-85748 Garching bei Muenchen (Germany); Koester, B. P. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States); Brinckmann, T. E.; Kristensen, M. T.; Lindholmer, M. O.; Nielsen, A.; Krogager, J.-K.; Fynbo, J. P. U., E-mail: hdahle@astro.uio.no [Dark Cosmology Centre, Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark)

2013-08-20T23:59:59.000Z

97

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

98

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

99

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

100

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

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


101

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 mas...

Natarajan, Aravind; Battaglia, Nicholas; Trac, Hy

2014-01-01T23:59:59.000Z

102

On the lensing effect of spiral galaxies  

E-Print Network [OSTI]

Jan 3, 2014 ... How does the internal structure of a spiral galaxy contribute to its gravitational lensing ... as well as Physics, her originality will be missed. ..... [1] M. Abramowitz, I. A. Stegun, Handbook of Mathematical Functions with. Formulas ...

2014-01-03T23:59:59.000Z

103

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 power spectrum can be measured to similar accuracy.

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

2014-09-04T23:59:59.000Z

104

New Constraints on the Faint-end of the UV Luminosity Function at z~7-8 using the Gravitational Lensing of the Hubble Frontier Fields Cluster A2744  

E-Print Network [OSTI]

Exploiting the power of gravitational lensing, the Hubble Frontier Fields (HFF) program aims at observing six massive galaxy clusters to explore the distant Universe far beyond the depth limits of blank field surveys. Using the complete {\\em Hubble Space Telescope} observations of the first HFF cluster Abell 2744, we report the detection of 50 galaxy candidates at $z \\sim 7$ and eight candidates at $z \\sim 8$ in a total survey area of 1.43 arcmin$^{2}$ in the source plane. Three of these galaxies are multiply-imaged by the lensing cluster. Using an updated model of the mass distribution in the cluster we were able to calculate the magnification factor and the effective survey volume for each galaxy in order to compute the ultraviolet galaxy luminosity function at both redshift 7 and 8. Our new measurements reliably extend the $z \\sim 7$ UV LF down to an absolute magnitude of $M_{UV} \\sim -16.5$. We find a faint-end slope $\\alpha = -1.88\\pm0.12$ close to previous determinations in blank fields. We show here fo...

Atek, Hakim; Kneib, Jean-Paul; Jauzac, Mathilde; Schaerer, Daniel; Clement, Benjamin; Limousin, Marceau; Jullo, Eric; Natarajan, Priyamvada; Egami, Eiichi; Ebeling, Harald

2014-01-01T23:59:59.000Z

105

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

106

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

107

Statistical lensing by galactic discs  

E-Print Network [OSTI]

The high-magnification gravitational lensing cross-section of a galaxy is enhanced significantly if a baryonic disc is embedded in its dark matter halo. We investigate the effects of a population of such disks on the probability of detecting strongly lensed images of distant galaxies and quasars. The optical depth to lensing is always more than doubled. The effects are particularly significant at magnifications greater than about 50, for which the optical depth typically increases by a factor greater than 5. If either the fraction of discs or the typical disc-to-halo mass ratio increases with redshift, then the optical depth is expected to be increased even further. Obscuration by dust in the lensing disc is expected to counteract the associated enhanced magnification bias for surveys in the optical waveband, but not in the radio and millimetre/submillimetre wavebands. The presence of galactic discs should hence lead to a significant increase in the number of lensed galaxies and quasars detected in both radio- and millimetre/submillimetre-selected surveys. An increase by a factor of about 3 is expected, enhancing the strong case for millimetre/submillimetre-wave lens surveys using the next generation of ground-based telescopes and the FIRST and Planck Surveyor space missions.

Andrew W. Blain; Ole Moeller; Ariyeh H. Maller

1998-10-23T23:59:59.000Z

108

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

109

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

110

Lensing by Lyman Limit Systems: Determining the Mass to Gas Ratio  

E-Print Network [OSTI]

We present a new method to determine the total mass-to-neutral gas ratio in Lyman-limits systems. The method exploits the relation between the neutral hydrogen column density and the magnification of background sources due to the weak gravitational lensing that these systems induce. Because weak lensing does not provide a direct measure of mass, one must use this relation in a statistical sense to solve for the average mass-to-gas ratio and its distribution. We use a detailed mock catalog of quasars (sources) and Lyman-limit systems (lenses) to demonstrate the applicability of this approach through our ability to recover the parameter. This mock catalog also allows us to check for systematics in the method and to sketch its limitations. For a universal constant mass-to-gas ratio and a sample of N quasars, we obtain an unbiased estimate of its value with 95% confidence limits (independent of its actual value) of +/- 140 {10^5/N)^0.5.

Ariyeh Maller; Tsafrir Kolatt; Matthias Bartelmann; George R. Blumenthal

2001-01-11T23:59:59.000Z

111

Measurement of Gravitational Lens Time Delays with LSST (SULI Paper)  

SciTech Connect (OSTI)

The proposed Large Synoptic Survey Telescope will be the first to explore multiple dark energy probes simultaneously, including baryon acoustic oscillations, weak lensing, and strong gravitational lensing. The large data sample, covering the entire visible sky every few nights, will allow an unprecedented survey of deep supernova sources and their lensed images. The latter have not yet been observed. Notably, LSST will measure the time delays between different strong-lensed images of the same supernova. This will provide a unique probe of dark matter, dark energy, and the expansion rate of the Universe. By simulating LSST observations under realistic conditions, we determined the time delay precision of multiple images from a representative strong-lensed Type Ia supernova. The output of the simulation was a set of light curves according to field and filter, which were subsequently analyzed to determine the experimental time delays. We find that a time delay precision of better then 10% can be achieved under suitable conditions. Firstly, a minimum observed peak-magnitude of 22 is required for the lensed image, corresponding to an intrinsic source magnitude of about 24. The number of such supernova sources expected for LSST is under investigation, but it could amount to several thousand. Secondly, a minimum of about 50 visits per field is required, and, moreover, these visits must be evenly distributed over the duration of the event. The visit frequency should be approximately once per week, or better. Thirdly, the sky brightness should be below 21 magnitude arcsec{sup -2} to allow sufficient sensitivity to distance sources. Under the nominal LSST visiting schedule and field conditions, 15% of all fields satisfy these criteria, and allow time delay measurements of better than 10% precision. This performance can be further improved by fitting the predicted supernova light curves to the observations, rather than using the simple weighted mean as in the present study. Of the well-measured fields, 85% involve observations taken with the r filter, which has a wavelength acceptance that is well-matched to supernova spectra. This filter therefore represents the best choice for strong gravitational lens observations with LSST. Our primary conclusion is that the visiting schedule is the single most important parameter to optimize for time delay measurements, and, once a lensed supernova has been detected, that frequent, regular observations should be scheduled to search with the highest sensitivity for multiple, delayed lensed images.

Kirkby, Lowry Anna; /Oxford U. /SLAC

2006-01-04T23:59:59.000Z

112

Weak lensing tomography with orthogonal polynomials  

Science Journals Connector (OSTI)

......of multiple polynomials lifts degeneracies. The assumption...polynomials, and as a last point we investigate how errors...structure has been detected by four independent research groups...Additionally, we would like to point out that line-of-sight...both arguments. Starting point for the construction of......

Björn Malte Schäfer; Lavinia Heisenberg

2012-07-11T23:59:59.000Z

113

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

114

Quasi-stellar Objects and Gravitational Lenses  

Science Journals Connector (OSTI)

... not very satisfactory. Treating the deflector as a spherical distribution of matter described by the Schwarzschild interior solution we find9

L. N. K. DE SILVA

1970-12-19T23:59:59.000Z

115

Strong gravitational lensing and dynamical dark energy  

Science Journals Connector (OSTI)

......investigate the nature of dark energy. The forthcoming observational surveys (i.e. CFHT Legacy Survey, SDSS and others...example, the RCS-2 Survey (Gladders et al...discussions on dynamical dark energy models. We also thank......

Andrea V. Macciò

2005-08-21T23:59:59.000Z

116

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

117

Probing Dark Energy with Lensing Magnification in Photometric Surveys  

E-Print Network [OSTI]

I present an estimator for the angular cross-correlation of two tracers of the cosmological large-scale structure that utilizes redshift information to isolate separate physical contributions. The estimator is derived by solving the Limber equation for a re-weighting of the foreground tracer that nulls either clustering or lensing contributions to the cross-correlation function. Applied to future photometric surveys, the estimator can enhance the measurement of gravitational lensing magnification effects to provide a competitive independent constraint on the dark energy equation of state.

Schneider, Michael D

2014-01-01T23:59:59.000Z

118

SIZE BIAS AND DIFFERENTIAL LENSING OF STRONGLY LENSED, DUSTY GALAXIES IDENTIFIED IN WIDE-FIELD SURVEYS  

SciTech Connect (OSTI)

We address two selection effects that operate on samples of gravitationally lensed dusty galaxies identified in millimeter- and submillimeter-wavelength surveys. First, we point out the existence of a ''size bias'' in such samples: due to finite source effects, sources with higher observed fluxes are increasingly biased toward more compact objects. Second, we examine the effect of differential lensing in individual lens systems by modeling each source as a compact core embedded in an extended diffuse halo. Considering the ratio of magnifications in these two components, we find that at high overall magnifications, the compact component is amplified by a much larger factor than the diffuse component, but at intermediate magnifications ({approx}10) the probability of a larger magnification for the extended region is higher. Lens models determined from multi-frequency resolved imaging data are crucial to correct for this effect.

Hezaveh, Yashar D.; Holder, Gilbert P. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Marrone, Daniel P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

2012-12-10T23:59:59.000Z

119

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

120

Weak lensing forecasts for dark energy, neutrinos and initial conditions  

Science Journals Connector (OSTI)

......understand the nature of dark energy. Future cosmic shear surveys show exceptional potential for constraining the dark energy equation of state w(z...quantify the potential for a survey to constrain dark energy parameters, we use the......

I. Debono; A. Rassat; A. Réfrégier; A. Amara; T. D. Kitching

2010-05-01T23:59:59.000Z

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


121

Bayesian model selection for dark energy using weak lensing forecasts  

Science Journals Connector (OSTI)

......cosmic shear surveys show exceptional...constraining the dark energy equation of state...potential for a survey to constrain dark energy parameters for...The fiducial survey will be able...between dynamical dark energy models and lambdaCDM......

Ivan Debono

2014-01-01T23:59:59.000Z

122

Bayesian model selection for dark energy using weak lensing forecasts  

Science Journals Connector (OSTI)

......this, but if dark energy really is lambda then...eds. (2009) New York: Am. Inst. Phys...Elgaroy o. , Lahav O. New J. Phys. (2005...Dark Matter and Dark Energy in the Universe-Cline...ed. (2009) New York: Am. Inst. Phys......

Ivan Debono

2014-01-01T23:59:59.000Z

123

Impact of Atmospheric Chromatic Effects on Weak Lensing Measurements  

E-Print Network [OSTI]

Current and future imaging surveys will measure cosmic shear with statistical precision that demands a deeper understanding of potential systematic biases in galaxy shape measurements than has been achieved to date. We use analytic and computational techniques to study the impact on shape measurements of two atmospheric chromatic effects for ground-based surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST): (i) atmospheric differential chromatic refraction (DCR) and (ii) wavelength dependence of seeing. We investigate the effects of using the point spread function (PSF) measured with stars to determine the shape of a galaxy that has a different spectral energy distribution (SED) than the stars. For (i), we extend a study by Plazas & Bernstein based on analytic calculations that show that DCR leads to significant biases in galaxy shape measurements for future surveys, if not corrected. For (ii), we find that the wavelength dependence of seeing leads to significant bia...

Meyers, Joshua E

2014-01-01T23:59:59.000Z

124

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

125

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

126

Continuous Limit of Multiple Gravitational Lens Effect and Average Magnification Factor  

E-Print Network [OSTI]

We show that the gravitational magnification factor averaged over all configurations of lenses in a locally inhomogeneous universe satisfy a second order differential equation with redshift $z$ by taking the continuous limit of multi-plane gravitational lens equation (the number $N$ of lenses $\\to\\infty$) and that the gravitationally magnified Dyer-Roeder distance in a clumpy universe becomes to that of the Friedmann-Lema\\^{\\i}tre universe for arbitrary values of the density parameter $\\Omega_{0}$ and of a mass fraction $\\bar{\\alpha}$ (smoothness parameter).

Hiroshi Yoshida; Kouji Nakamura; Minoru Omote

2003-04-01T23:59:59.000Z

127

Next Generation Strong Lensing Time Delay Estimation with Gaussian Processes  

E-Print Network [OSTI]

Strong gravitational lensing forms multiple, time delayed images of cosmological sources, with the "focal length" of the lens serving as a cosmological distance probe. Robust estimation of the time delay distance can tightly constrain the Hubble constant as well as the matter density and dark energy. Current and next generation surveys will find hundreds to thousands of lensed systems but accurate time delay estimation from noisy, gappy lightcurves is potentially a limiting systematic. Using a large sample of blinded lightcurves from the Strong Lens Time Delay Challenge we develop and demonstrate a Gaussian Process crosscorrelation technique that delivers an average bias within 0.1% depending on the sampling, necessary for subpercent Hubble constant determination. The fits are accurate (80% of them within 1 day) for delays from 5-100 days and robust against cadence variations shorter than 6 days. We study the effects of survey characteristics such as cadence, season, and campaign length, and derive requiremen...

Hojjati, Alireza

2014-01-01T23:59:59.000Z

128

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

129

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

130

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

131

Gravitation Revisited  

E-Print Network [OSTI]

Gravitation has posed a puzzle and a problem for many decades. Attempts to unify it with other fundamental interactions have failed. These problems and puzzles have been underscored by the likes of Witten and Weinberg. We survey this and argue that gravitation has a different character compared to other fundamental interactions - it is an energy distributed over all the elementary particles in the universe. The above puzzle and problem is resolved satisfactorily. These considerations lead to a varying $G$ cosmology consistent with observation. It is argued that apart from the usual tests, the above explains in addition the anomalous accelerations of the Pioneer spacecrafts. Further tests are also proposed.

B. G. Sidharth

2006-04-06T23:59:59.000Z

132

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

133

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...

134

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

E-Print Network [OSTI]

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

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

2008-08-19T23:59:59.000Z

135

The Weak Aggregating Algorithm and Weak Mixability  

E-Print Network [OSTI]

of the Weak Aggregating Algorithm that covers unbounded games is also described. #12; CONTENTS 2 Contents 1The Weak Aggregating Algorithm and Weak Mixability Yuri Kalnishkan Michael V. Vyugin 1 fyura the Weak Aggregating Algorithm that allows us to obtain additive terms of the form C p n. A modification

Kalnishkan, Yuri

136

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

137

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

138

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

139

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

140

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

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

Constraints on Scalar-Field Dark Energy from the Cosmic Lens All-Sky Survey Gravitational Lens Statistics  

E-Print Network [OSTI]

We use the statistics of strong gravitational lensing based on the Cosmic Lens All-Sky Survey (CLASS) data to constrain cosmological parameters in a spatially-flat, inverse power-law potential energy density, scalar-field dark energy cosmological model. The lensing-based constraints are consistent with, but weaker than, those derived from Type Ia supernova redshift-magnitude data, and mildly favor the Einstein cosmological constant limit of this dark energy model.

Kyu-Hyun Chae; Gang Chen; Bharat Ratra; Dong-Wook Lee

2004-03-10T23:59:59.000Z

142

Gravitational waves from cosmic bubble collisions  

E-Print Network [OSTI]

Cosmic bubbles are nucleated through the quantum tunneling process. After nucleation they would expand and undergo collisions with each other. In this paper, we focus in particular on collisions of two equal-sized bubbles and compute gravitational waves emitted from the collisions. First, we study the mechanism of the collisions by means of a real scalar field and a quartic potential of the field. Then, using this scalar field model, we compute gravitational waves from the collisions in a straightforward manner. In the quadrupole approximation, time-domain gravitational waveforms are directly obtained by integrating the energy-momentum tensors over the volume of the wave sources, where the energy-momentum tensors are expressed in terms of the scalar field, the local geometry and the potential; therefore, containing all information about the bubble collisions. We present gravitational waveforms emitted during (i) the initial-to-intermediate stage of strong collisions and (ii) the final stage of weak collisions...

Kim, Dong-Hoon; Lee, Wonwoo; Yang, Jongmann; Yeom, Dong-han

2014-01-01T23:59:59.000Z

143

Spectroscopic Gravitational Lens Candidates in the CNOC2 Field Galaxy Redshift Survey  

E-Print Network [OSTI]

We present five candidate gravitational lenses discovered spectroscopically in the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2), along with one found in followup observations. Each has a secure redshift based on several features, plus a discrepant emission line which does not match any known or plausible feature and is visible in multiple direct spectral images. We identify these lines as Lyman-alpha or [OII] emission from galaxies lensed by, or projected onto, the CNOC2 target galaxies. Einstein radii estimated from the candidate deflector galaxy luminosities indicate that for two candidates the lines are probably [OII] from projected z3 galaxies. We estimate that only 1.9+-0.7 [OII]-emitting galaxies are expected to project onto target galaxies in the original CNOC2 sample, consistent with three or four of the six candidates being true gravitational lenses.

Patrick B. Hall; H. K. C. Yee; Huan Lin; Simon L. Morris; Michael D. Gladders; R. G. Carlberg; David R. Patton; Marcin Sawicki; Charles W. Shepherd; Gregory D. Wirth

2000-06-29T23:59:59.000Z

144

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

145

Dark Energy Constraints from the CTIO Lensing Survey  

Science Journals Connector (OSTI)

We perform a cosmological parameter analysis of the 75 deg2 CTIO lensing survey in conjunction with cosmic microwave background (CMB) and Type Ia supernovae data. For ?CDM cosmologies, we find that the amplitude of the power spectrum at low redshift is given by ?8 = 0.81 (95% confidence level), where the error bound includes both statistical and systematic errors. The total of all systematic errors is smaller than the statistical errors, but they do make up a significant fraction of the error budget. We find that weak lensing improves the constraints on dark energy as well. The (constant) dark energy equation of state parameter, w, is measured to be -0.89 (95% c.l.). Marginalizing over a constant w slightly changes the estimate of ?8 to 0.79 (95% c.l.). We also investigate variable w cosmologies but find that the constraints weaken considerably; next-generation surveys are needed to obtain meaningful constraints on the possible time evolution of dark energy.

Mike Jarvis; Bhuvnesh Jain; Gary Bernstein; Derek Dolney

2006-01-01T23:59:59.000Z

146

Dark Energy Constraints from the CTIO Lensing Survey  

E-Print Network [OSTI]

We perform a cosmological parameter analysis of the 75 square degree CTIO lensing survey in conjunction with CMB and Type Ia supernovae data. For Lambda CDM cosmologies, we find that the amplitude of the power spectrum at low redshift is given by sigma_8 = 0.81 (+0.15,-0.10, 95% c.l.), where the error bar includes both statistical and systematic errors. The total of all systematic errors is smaller than the statistical errors, but they do make up a significant fraction of the error budget. We find that weak lensing improves the constraints on dark energy as well. The (constant) dark energy equation of state parameter, w, is measured to be -0.89 (+0.16,-0.21, 95% c.l.). Marginalizing over a constant $w$ slightly changes the estimate of sigma_8 to 0.79 (+0.17, -0.14, 95% c.l.). We also investigate variable w cosmologies, but find that the constraints weaken considerably; the next generation surveys are needed to obtain meaningful constraints on the possible time evolution of dark energy.

Mike Jarvis; Bhuvnesh Jain; Gary Bernstein; Derek Dolney

2005-02-14T23:59:59.000Z

147

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

148

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

149

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

150

Gravitational Wave Induced Vibrations of Slender Structures in Space  

E-Print Network [OSTI]

This paper explores the interaction of weak gravitational fields with slender elastic materials in space and estimates their sensitivities for the detection of gravitational waves with frequencies between $10^{-4}$ and 1 Hz. The dynamic behaviour of such slender structures is ideally suited to analysis by the simple theory of Cosserat rods. Such a description offers a clean conceptual separation of the vibrations induced by bending, shear, twist and extension and the response to gravitational tidal accelerations can be reliably estimated in terms of the constitutive properties of the structure. The sensitivity estimates are based on a truncation of the theory in the presence of thermally induced homogeneous Gaussian stochastic forces.

R W Tucker; C Wang

2001-12-06T23:59:59.000Z

151

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

152

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

153

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

154

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

E-Print Network [OSTI]

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

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

2008-02-11T23:59:59.000Z

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

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

157

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

158

Gravitation and Magnetism  

Science Journals Connector (OSTI)

......1 August 1950 research-article Articles Gravitation and Magnetism E. A. Milne It is shown by the methods of kinematic relativity that there should be a connection between gravitation and magnetism of the type suggested by the empirical formulae of Blackett......

E. A. Milne

1950-08-01T23:59:59.000Z

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

Energy conversion by gravitational waves  

Science Journals Connector (OSTI)

... out that if such particles are charged, the accelerations will constitute a mechanism for the conversion of gravitational ... of gravitational energy into electromagnetic ...

H. BONDI; F. A. E. PIRANI

1988-03-17T23:59:59.000Z

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

Measuring dark energy properties with 3D cosmic shear  

Science Journals Connector (OSTI)

......weak-lensing surveys are extremely promising for measuring dark energy properties. gravitational...lensing with other dark energy probes and discuss future surveys and finally we...Gemini) or the Dark Energy Survey (Wester 2005......

A. F. Heavens; T. D. Kitching; A. N. Taylor

2006-11-21T23:59:59.000Z

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

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

164

Quantized Gravitational Field. II  

Science Journals Connector (OSTI)

A consistent formulation is given for the quantized gravitational field in interaction with integer spin fields. Lorentz transformation equivalence within a class of physically distinguished coordinate systems is verified.

Julian Schwinger

1963-11-01T23:59:59.000Z

165

Ellipticity of dark matter haloes with galaxy–galaxy weak lensing  

Science Journals Connector (OSTI)

......Gunn J. E., Ivezic Z., Knapp G. R., Kent S., Yasuda N., 2001, in Harnden F. R. Jr, Primini F. A., Payne H. E...269. MacGillivray H. T. , Dodd R. J., McNally B. V., Corwin H. G., 1982......

Rachel Mandelbaum; Christopher M. Hirata; Tamara Broderick; Uros Seljak; Jonathan Brinkmann

2006-08-01T23:59:59.000Z

166

Sources of contamination to weak lensing tomography: redshift-dependent shear measurement bias  

Science Journals Connector (OSTI)

......observations. We quantify the constraints using a figure-of-merit (FoM) defined as the inverse of the area enclosed by the 68...http://www.ifa.hawaii.edu/kaiser/ , developed by Nick Kaiser. We warmly thank the participants of the STEP collaboration......

Elisabetta Semboloni; Ismael Tereno; Ludovic Van Waerbeke; Catherine Heymans

2009-08-01T23:59:59.000Z

167

The Shear Testing Programme 2: Factors affecting high-precision weak-lensing analyses  

Science Journals Connector (OSTI)

......2004; Jarvis Jain 2004). As in STEP1, the main figure of merit throughout our analysis will be the mean shear measured within...the COSMOS collaboration, particularly Anton Koekemoer and Nick Scoville, for providing the high-resolution HST images from......

Richard Massey; Catherine Heymans; Joel Bergé; Gary Bernstein; Sarah Bridle; Douglas Clowe; Håkon Dahle; Richard Ellis; Thomas Erben; Marco Hetterscheidt; F. William High; Christopher Hirata; Henk Hoekstra; Patrick Hudelot; Mike Jarvis; David Johnston; Konrad Kuijken; Vera Margoniner; Rachel Mandelbaum; Yannick Mellier; Reiko Nakajima; Stephane Paulin-Henriksson; Molly Peeples; Chris Roat; Alexandre Refregier; Jason Rhodes; Tim Schrabback; Mischa Schirmer; Uros Seljak; Elisabetta Semboloni; Ludovic Van Waerbeke

2007-03-21T23:59:59.000Z

168

Disentangling dark energy and cosmic tests of gravity from weak lensing systematics  

Science Journals Connector (OSTI)

......structure surveys such as the Dark Energy Survey (DES), the Subaru Measurement...Hyper Suprime-Cam,3 the Dark Energy Survey (DES)4 and the Large Synoptic...for optimizing cosmic shear surveys to measure dark energy in a related paper (Kirk......

Istvan Laszlo; Rachel Bean; Donnacha Kirk; Sarah Bridle

2012-06-21T23:59:59.000Z

169

Accuracy of photometric redshifts for future weak lensing surveys from space  

Science Journals Connector (OSTI)

......Survey Telescope (LSST), Pan-STARRS and Dark Energy Survey (DES). The results highlight the importance...ground-based telescopes [e.g. Kilo-Degree Survey, Pan-STARRS, Dark Energy Survey (DES), Large Synoptic Survey Telescope......

F. Bellagamba; M. Meneghetti; L. Moscardini; M. Bolzonella

2012-05-01T23:59:59.000Z

170

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

171

Probing dark energy and neutrino mass from upcoming lensing experiments of CMB and galaxies  

SciTech Connect (OSTI)

We discuss the synergy of the cosmic shear and CMB lensing experiments to simultaneously constrain the neutrino mass and dark energy properties. Taking fully account of the CMB lensing, cosmic shear, CMB anisotropies, and their cross correlation signals, we clarify a role of each signal, and investigate the extent to which the upcoming observations by a high-angular resolution experiment of CMB and deep galaxy imaging survey can tightly constrain the neutrino mass and dark energy equation-of-state parameters. Including the primary CMB information as a prior cosmological information, the Fisher analysis reveals that the time varying equation-of-state parameters, given by w(a) = w{sub 0}+w{sub a}(1?a), can be tightly constrained with the accuracies of 5% for w{sub 0} and 15% for w{sub a}, which are comparable to or even better than those of the stage-III type surveys neglecting the effect of massive neutrinos. In other words, including the neutrino mass in the parameter estimation would not drastically alter the figure-of-Merit estimates of dark energy parameters from the weak lensing measurements. For the neutrino mass, a clear signal for total neutrino mass with ? 0.1 eV can be detected with ? 2-? significance. The robustness and sensitivity of these results are checked in detail by allowing the setup of cosmic shear experiment to vary as a function of observation time or exposure time, showing that the improvement of the constraints very weakly depends on the survey parameters, and the results mentioned above are nearly optimal for the dark energy parameters and the neutrino mass.

Namikawa, Toshiya; Saito, Shun [Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan); Taruya, Atsushi, E-mail: namikawa@utap.phys.s.u-tokyo.ac.jp, E-mail: ssaito@astro.berkeley.edu, E-mail: ataruya@utap.phys.s.u-tokyo.ac.jp [Research Center for the Early Universe, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2010-12-01T23:59:59.000Z

172

Isolating the decay rate of cosmological gravitational potential  

E-Print Network [OSTI]

The decay rate of cosmological gravitational potential measures the deviation from Einstein-de Sitter universe and can put strong constraints on the nature of dark energy and gravity. Usual method to measure this decay rate is through the integrated Sachs-Wolfe (ISW) effect-large scale structure (LSS) cross correlation. However, the interpretation of the measured correlation signal is complicated by the galaxy bias and matter power spectrum. This could bias and/or degrade its constraints to the nature of dark energy and gravity. But, combining the lensing-LSS cross correlation measurements, the decay rate of gravitational potential can be isolated. For any given narrow redshift bin of LSS, the ratio of the two cross correlations directly measures $[d\\ln D_{\\phi}/d\\ln a]H(z)/W(\\chi,\\chi_s)$, where $D_{\\phi}$ is the linear growth factor of the gravitational potential, $H$ is the Hubble constant at redshift $z$, $W(\\chi,\\chi_s)$ is the lensing kernel and $\\chi$ and $\\chi_s$ are the comoving angular diameter distance to lens and source, respectively. This method is optimal in the sense that (1) the measured quantity is essentially free of systematic errors and is only limited by cosmic variance and (2) the measured quantity only depends on several cosmological parameters and can be predicted from first principles unambiguously. Though fundamentally limited by inevitably large cosmic variance associated with the ISW measurements, it can still put useful independent constraints on the amount of dark energy and its equation of state. It can also provide a powerful test of modified gravity and can distinguish the Dvali-Gabadadze-Porrati model from $\\Lambda$CDM at $>2.5\\sigma$ confidence level.

Pengjie Zhang

2005-12-16T23:59:59.000Z

173

Dark Matter Gravitational Interactions  

E-Print Network [OSTI]

We argue that the conjectured dark mater in the Universe may be endowed with a new kind of gravitational charge that couples to a short range gravitational interaction mediated by a massive vector field. A model is constructed that assimilates this concept into ideas of current inflationary cosmology. The model is also consistent with the observed behaviour of galactic rotation curves according to Newtonian dynamics. The essential idea is that stars composed of ordinary (as opposed to dark matter) experience Newtonian forces due to the presence of an all pervading background of massive gravitationally charged cold dark matter. The novel gravitational interactions are predicted to have a significant influence on pre-inflationary cosmology. The precise details depend on the nature of a gravitational Proca interaction and the description of matter. A gravitational Proca field configuration that gives rise to attractive forces between dark matter charges of like polarity exhibits homogeneous isotropic eternal cosmologies that are free of cosmological curvature singularities thus eliminating the horizon problem associated with the standard big-bang scenario. Such solutions do however admit dense hot pre-inflationary epochs each with a characteristic scale factor that may be correlated with the dark matter density in the current era of expansion. The model is based on a theory in which a modification of Einsteinian gravity at very short distances can be expressed in terms of the gradient of the Einstein metric and the torsion of a non-Riemannian connection on the bundle of linear frames over spacetime. Indeed we demonstrate that the genesis of the model resides in a remarkable simplification that occurs when one analyses the variational equations associated with a broad class of non-Riemannian actions.

R. W. Tucker; C. Wang

1996-12-09T23:59:59.000Z

174

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

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

Steven Weinberg, Weak Interactions, and Electromagnetic Interactions  

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

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

177

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

178

Gravitation and Thermodynamics  

Science Journals Connector (OSTI)

... THE suggestion in NATURE of March 1 that thermodynamics might throw light on the question of the temperature variation of gravitation has not been ... unkindly received. The criticisms have not been directed so much against this suggested application of thermodynamics as against the expression deduced for the attraction between two bodies. ...

GEORGE W. TODD

1917-04-05T23:59:59.000Z

179

A gravitational puzzle  

Science Journals Connector (OSTI)

...not merely the stress-energy tensor of gravitating...context, if the source energy density and pressure...cosmological constant plus cold dark matter scenario, but...gap between the matter energy density and the expansion...Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) WL data...

2011-01-01T23:59:59.000Z

180

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

Note: This page contains sample records for the topic "weak gravitational lensing" from the National Library of EnergyBeta (NLEBeta).
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181

Action of the gravitational field on the dynamical Casimir effect  

E-Print Network [OSTI]

In this paper we analyze the action of the gravitational field on the dynamical Casimir effect. We consider a massless scalar field confined in a cuboid cavity placed in a gravitational field described by a static and diagonal metric. With one of the plane mirrors of the cavity allowed to move, we compute the average number of particles created inside the cavity by means of the Bogoliubov coefficients computed through perturbative expansions. We apply our result to the case of an oscillatory motion of the mirror, assuming a weak gravitational field described by the Schwarzschild metric. The regime of parametric amplification is analyzed in detail, demonstrating that our computed result for the mean number of particles created agrees with specific associated cases in the literature. Our results, obtained in the framework of the perturbation theory, are restricted, under resonant conditions, to a short-time limit.

Céleri, L C; Moussa, M H Y

2008-01-01T23:59:59.000Z

182

Action of the gravitational field on the dynamical Casimir effect  

E-Print Network [OSTI]

In this paper we analyze the action of the gravitational field on the dynamical Casimir effect. We consider a massless scalar field confined in a cuboid cavity placed in a gravitational field described by a static and diagonal metric. With one of the plane mirrors of the cavity allowed to move, we compute the average number of particles created inside the cavity by means of the Bogoliubov coefficients computed through perturbative expansions. We apply our result to the case of an oscillatory motion of the mirror, assuming a weak gravitational field described by the Schwarzschild metric. The regime of parametric amplification is analyzed in detail, demonstrating that our computed result for the mean number of particles created agrees with specific associated cases in the literature. Our results, obtained in the framework of the perturbation theory, are restricted, under resonant conditions, to a short-time limit.

L. C. Céleri; F. Pascoal; M. H. Y. Moussa

2008-09-22T23:59:59.000Z

183

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

184

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

185

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

186

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

187

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

188

Statistical and systematic uncertainties in pixel-based source reconstruction algorithms for gravitational lensing  

Science Journals Connector (OSTI)

......hence the number of source pixels that cover the source is smaller. (The colour version...outer regions of the analytic profile, we set the analytic source flux to 10 per cent...resolution is 0.05 arcsec-pixel1. For each set of observations, the middle column corresponds......

Amitpal S. Tagore; Charles R. Keeton

2014-01-01T23:59:59.000Z

189

Gravitational lensing with f () = 3/2 gravity in accordance with astrophysical observations  

Science Journals Connector (OSTI)

......action (8) includes the Schwarzschild mass (through L M ) in the...This is not surprising as it mirrors the analogous unfolding of...Einstein's general relativity Schwarzschild's metric holds, and therefore...identifies the coefficients of the Schwarzschild metric, and M T(r......

S. Mendoza; T. Bernal; X. Hernandez; J. C. Hidalgo; L. A. Torres

2013-01-01T23:59:59.000Z

190

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

191

Quantized Gravitational Field  

Science Journals Connector (OSTI)

A gravitational action operator is constructed that is invariant under general coordinate transformations and local Lorentz (gauge) transformations. To interpret the formalism the arbitrariness in description must be restricted by introducing gauge conditions and coordinate conditions. The time gauge is defined by locking the time axes of the local coordinate systems to the general coordinate time axis. The resulting form of the action operator, including the contribution of a spinless matter field, enables canonical pairs of variables to be identified. There are four field variables that lack canonical partners, in virtue of differential constraint equations, which can be interpreted as space-time coordinate displacements. In a physically distinguished class of coordinate system the gravitational field variables are not explicit functions of the coordinate displacement parameters. There remains the freedom of Lorentz transformation. The generators of spatial translations and rotations have the correct commutation properties. The question of Lorentz invariance is left undecided since the energy density operator is only given implicitly.

Julian Schwinger

1963-05-01T23:59:59.000Z

192

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

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

Morphology and ultrastructure of fungi in extended-wear soft contact lenses.  

Science Journals Connector (OSTI)

...and disinfection of extended-wear contact lenses is advisable...while wearing current extended-wear lenses, or the lenses should...CITED 1. Berger, R. O., and B. W. Streeten. 1981. Fungal growth...soft contact lenses in extended wear. Folia Ophthalmol. Jpn. 35...

R B Simmons; J R Buffington; M Ward; L A Wilson; D G Ahearn

1986-07-01T23:59:59.000Z

195

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

196

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

197

A millimeter-wave antireflection coating for cryogenic silicon lenses  

E-Print Network [OSTI]

We have developed and tested an antireflection (AR) coating method for silicon lenses at cryogenic temperatures and millimeter wavelengths. Our particular application is a measurement of the cosmic microwave background. The coating consists of machined pieces of Cirlex glued to the silicon. The measured reflection from an AR coated flat piece is less than 1.5% at the design wavelength. The coating has been applied to flats and lenses and has survived multiple thermal cycles from 300 to 4 K. We present the manufacturing method, the material properties, the tests performed, and estimates of the loss that can be achieved in practical lenses.

J. M. Lau; J. W. Fowler; T. A. Marriage; L. Page; J. Leong; E. Wishnow; R. Henry; E. Wollck; M. Halpern; D. Marsden; G. Marsden

2007-01-04T23:59:59.000Z

198

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

199

Quantum Emulation of Gravitational Waves  

E-Print Network [OSTI]

Gravitational waves, as predicted by Einstein's general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials.

Ivan Fernandez-Corbaton; Mauro Cirio; Alexander Büse; Lucas Lamata; Enrique Solano; Gabriel Molina-Terriza

2014-06-17T23:59:59.000Z

200

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

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

Measuring the speed of cosmological gravitational waves  

E-Print Network [OSTI]

In general relativity gravitational waves propagate at the speed of light, however in alternative theories of gravity that might not be the case. We study the effects of a modified speed of gravity, $c_T^2$, on the B-modes of the Cosmic Microwave Background (CMB) anisotropy in polarisation. We find that a departure from the light speed value would leave a characteristic imprint on the BB spectrum part induced by tensors, manifesting as a shift in the angular scale of its peaks. We derive constraints by using the available {\\it Planck} and BICEP2 datasets showing how $c_T^2$ can be measured, albeit obtaining weak constraints due to the overall poor accuracy of the current BB power spectrum measurements. The present constraint corresponds to $c_T^2 = 1.30 \\pm 0.79$ and $c_T^2measurements, largely due to the absence of degeneracy with other cosmological parameters.

Marco Raveri; Carlo Baccigalupi; Alessandra Silvestri; Shuang-Yong Zhou

2014-05-30T23:59:59.000Z

202

Measuring the speed of cosmological gravitational waves  

E-Print Network [OSTI]

We study the effects of a modified speed of gravitational waves (tensor modes), $c_T^2$ on the B-modes of the Cosmic Microwave Background (CMB) anisotropy in polarisation. We find that a departure from the light speed value would leave a characteristic imprint on the BB spectrum part induced by tensors, manifesting as a shift in the angular scale of its peaks. We derive constraints by using the available Planck and BICEP2 datasets showing how $c_T^2$ can be measured, albeit obtaining weak constraints due to the overall poor accuracy of the current BB power spectrum measurements. The present constraint corresponds to $c_T^2 = 1.30 \\pm 0.79$ and $c_T^2measurements, largely due...

Raveri, Marco; Zhou, Shuang-Yong

2014-01-01T23:59:59.000Z

203

Gravitational lens optical scalars in terms of energy-momentum distributions  

SciTech Connect (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.

Gallo, Emanuel; Moreschi, Osvaldo M. [Facultad de Matematica, Astronomia, y Fisica, FaMAF, Universidad Nacional de Cordoba, Instituto de Fisica Enrique Gaviola, IFEG, CONICET Ciudad Universitaria, (5000) Cordoba (Argentina)

2011-04-15T23:59:59.000Z

204

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

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

Aspherical refractive lenses for small-angle neutron scattering  

Science Journals Connector (OSTI)

This paper discusses the testing and simulation of aspherical neutron lenses as focusing elements for small-angle neutron scattering and their transparency with respect to thermal diffuse scattering.

Frielinghaus, H.

2009-06-20T23:59:59.000Z

207

Focusing Kinoform Lenses: Optical Design and Experimental Validation  

SciTech Connect (OSTI)

X-ray focusing lenses with a kinoform profile are high brilliance optics that can produce nano-sized beams on 3rd generation synchrotron beamlines. The lenses are fabricated with sidewalls of micrometer lateral size. They are virtually non-absorbing and therefore can deliver a high flux over a good aperture. We are developing silicon and germanium lenses that will focus hard x-ray beams to less than 0.5 {mu}m size using a single refractive element. In this contribution, we present preliminary optical design and experimental test carried out on ID06 ESRF: the lenses were used to image directly the undulator source, providing a beam with fwhm of about 0.7 {mu}m.

Alianelli, Lucia; Sawhney, Kawal J. S. [Diamond Light Source Ltd, Didcot OX11 0DE (United Kingdom); Snigireva, Irina; Snigirev, Anatoly [European Synchrotron Radiation Facility, BP 220 38043 Grenoble Cedex (France)

2010-06-23T23:59:59.000Z

208

Improved constraint on the primordial gravitational-wave density using recent cosmological data and its impact on cosmic string models  

E-Print Network [OSTI]

The production of a primordial stochastic gravitational-wave background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's evolutionary history. Probes like the Cosmic Microwave Background (CMB) or the Baryon Acoustic Oscillations (BAO) can be used to set upper limits on the stochastic gravitational-wave background energy density $\\Omega_{GW}$ for frequencies above $10^{-15}$ Hz. We perform a profile likelihood analysis of the Planck CMB temperature anisotropies and gravitational lensing data combined with WMAP low-$\\ell$ polarization, BAO, South Pole Telescope and Atacama Cosmology Telescope data. We find that $\\Omega_{GW}h_{0}^{2} strings, we have derived exclusion limits in th...

Henrot-Versillé, Sophie; Leroy, Nicolas; Plaszczynski, Stéphane; Arnaud, Nicolas; Bizouard, Marie-Anne; Cavalier, Fabien; Christensen, Nelson; Couchot, François; Franco, Samuel; Hello, Patrice; Huet, Dominique; Kasprzack, Marie; Perdereau, Olivier; Spinelli, Marta; Tristram, Matthieu

2014-01-01T23:59:59.000Z

209

Electricity and Gravitation  

Science Journals Connector (OSTI)

Electric Doublet Theory of Gravitation.—It is suggested that gravitation may be an effect arising from fluctuations of the electric charges associated with the electrons and positive nuclei of atoms. It is assumed (1) that the ether contains an enormous number of electric doublets moving in all directions with the speed of light; (2) that each charged particle is continually both absorbing and emitting doublets at a rate proportional to its mass; and (3) that during the absorption and emission of each doublet the charge on the particle fluctuates. If these fluctuations exist, it is shown that the mean value of the force exerted by one charged particle on another includes, in addition to the ordinary electrostatic force, an attraction proportional to the product of the masses.Electric Doublet Theory of Radiation.—If we suppose that the doublets emitted by a particle possess available energy only when the energy of the particle changes, and that the effect of changing the energy is to produce periodic gaps in the emission of doublets with a frequency proportional to the amount of energy lost, we have a theory of radiation which is said to be compatible with the theories of Bohr, Planck and Einstein.

H. Bateman

1921-01-01T23:59:59.000Z

210

Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing  

DOE Patents [OSTI]

The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10[sup [minus]5] cm[sup [minus]1] has been demonstrated using this technique. 6 figs.

Cremers, D.A.; Keller, R.A.

1985-10-01T23:59:59.000Z

211

LBT/LUCIFER OBSERVATIONS OF THE z {approx} 2 LENSED GALAXY J0900+2234  

SciTech Connect (OSTI)

We present rest-frame optical images and spectra of the gravitationally lensed, star-forming galaxy J0900+2234 (z = 2.03). The observations were performed with the newly commissioned LUCIFER1 near-infrared (NIR) instrument mounted on the Large Binocular Telescope. We fitted lens models to the rest-frame optical images and found that the galaxy has an intrinsic effective radius of 7.4 {+-} 0.8 kpc with a lens magnification factor of about 5 for the A and B components. We also discovered a new arc belonging to another lensed high-z source galaxy, which makes this lens system a potential double Einstein ring system. Using the high signal-to-noise ratio rest-frame spectra covered by the H + K band, we detected H{beta}, [O III], H{alpha}, [N II], and [S II] emission lines. Detailed physical properties of this high-z galaxy were derived. The extinction toward the ionized H II regions (E{sub g} (B - V)) was computed from the flux ratio of H{alpha} and H{beta} and appears to be much higher than that toward the stellar continuum (E{sub s} (B - V)), derived from the optical and NIR broadband photometry fitting. The metallicity was estimated using N2 and O3N2 indices. It is in the range of 1/5 - 1/3 solar abundance, which is much lower than for typical z {approx} 2 star-forming galaxies. From the flux ratio of [S II]{lambda}6717 and [S II]{lambda}6732, we found that the electron number density of the H II regions in the high-z galaxy was {approx_equal}1000 cm{sup -3}, consistent with other z {approx} 2 galaxies but much higher than that in local H II regions. The star formation rate was estimated via the H{alpha} luminosity, after correction for the lens magnification, to be about 365 {+-} 69 M{sub sun} yr{sup -1}. Combining the FWHM of H{alpha} emission lines and the half-light radius, we found that the dynamical mass of the lensed galaxy is (5.8 {+-} 0.9) x 10{sup 10} M{sub sun}. The gas mass is (5.1 {+-} 1.1) x 10{sup 10} M{sub sun} from the H{alpha} flux surface density using global Kennicutt-Schmidt law, indicating a very high gas fraction of 0.79 {+-} 0.19 in J0900+2234.

Bian Fuyan; Fan Xiaohui; Bechtold, Jill; McGreer, Ian D.; Just, Dennis W. [Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Sand, David J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Green, Richard F.; Thompson, David [Large Binocular Telescope Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Peng, Chien Y. [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, British Columbia, V9E 2E7 (Canada); Seifert, Walter [Landessternwarte Koenigstuhl, Zentrum fuer Astronomie Heidelberg, Koenigstuhl 12, 69117 Heidelberg (Germany); Ageorges, Nancy; Buschkamp, Peter [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Juette, Marcus; Knierim, Volker [Astronomisches Institut, Ruhr-Universitaet, Universitaetstrasse 150, D-44780 Bochum (Germany)

2010-12-20T23:59:59.000Z

212

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

213

BayesWave: Bayesian Inference for Gravitational Wave Bursts and Instrument Glitches  

E-Print Network [OSTI]

A central challenge in Gravitational Wave Astronomy is identifying weak signals in the presence of non-stationary and non-Gaussian noise. The separation of gravitational wave signals from noise requires good models for both. When accurate signal models are available, such as for binary Neutron star systems, it is possible to make robust detection statements even when the noise is poorly understood. In contrast, searches for "un-modeled" transient signals are strongly impacted by the methods used to characterize the noise. Here we take a Bayesian approach and introduce a multi-component, variable dimension, parameterized noise model that explicitly accounts for non-stationarity and non-Gaussianity in data from interferometric gravitational wave detectors. Instrumental transients (glitches) and burst sources of gravitational waves are modeled using a Morlet-Gabor continuous wavelet basis. The number and placement of the wavelets is determined by a trans-dimensional Reversible Jump Markov Chain Monte Carlo algor...

Cornish, Neil J

2014-01-01T23:59:59.000Z

214

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

215

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

216

Probing the Proton's Weak Side | Jefferson Lab  

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

proton. The weak force is one of four fundamental forces, which include electromagnetism, gravity and the strong force. The weak force acts on subatomic particles, such...

217

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

218

Weak detonations, their paths and  

Science Journals Connector (OSTI)

Previously, a quasi-steady form of the classical Rankine-Hugoniot weak detonation has been shown to play an integral part in describing certain forms of detonation initiation, arising during an intermediate stage between the thermal ignition of the material and the first appearance of a strong detonation with Zeldovich-von Neumann-Döring (ZND) structure. In this paper, we use a parametric variable integration to calculate numerically the path of the weak detonation in two important initiation scenarios, shock-induced and initial disturbance-induced transition to detonation, via a large activation energy induction domain model. The influence that the nature of the path may have on the weak detonation structure is also discussed. In each case these calculations enable us to predict how, where and when the transition to a strong detonation with ZND structure will occur. Explanations for several phenomena observed in both experiments and numerical studies on transition to detonation are also uncovered by these calculations.

Mark Short; J W Dold

2002-01-01T23:59:59.000Z

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

Weak Localization in Bilayer Graphene  

Science Journals Connector (OSTI)

We have performed the first experimental investigation of quantum interference corrections to the conductivity of a bilayer graphene structure. A negative magnetoresistance—a signature of weak localization—is observed at different carrier densities, including the electroneutrality region. It is very different, however, from the weak localization in conventional two-dimensional systems. We show that it is controlled not only by the dephasing time, but also by different elastic processes that break the effective time-reversal symmetry and provide intervalley scattering.

R. V. Gorbachev; F. V. Tikhonenko; A. S. Mayorov; D. W. Horsell; A. K. Savchenko

2007-04-26T23:59:59.000Z

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

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

E-Print Network [OSTI]

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

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

2002-11-04T23:59:59.000Z

222

Sources of Weakness in Glass  

Science Journals Connector (OSTI)

...October 1964 research-article Sources of Weakness in Glass C. Gurney The theoretical strength of glass is of the order of 2 to 5 MLb./in.$^2$ At room temperature, common glasses with undamaged surfaces give breaking stresses of about...

1964-01-01T23:59:59.000Z

223

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

224

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

225

Fresnel and refractive lenses for X-rays  

Science Journals Connector (OSTI)

We present a Gaussian beam analysis of X-ray refractive and Fresnel lenses. The X-ray refractive lens is featured by an intrinsic soft (Gaussian) aperture due to strong absorption of X-rays by materials. We defined a parameter N0, the critical Fresnel number (CFN), to describe this optical property. The values of N0 for all practical materials are below 1000 for photon energies exceeding 30 eV, still lower for high-Z materials. The maximum effective Fresnel number of a lens is determined by its material to be 2N0 and its maximum enhancement of X-ray intensity is limited to (2?N0)2, independent of its shape. We found that the refractive lens is likely to be useful for manipulating nearly diffraction limited beam in the hard X-ray region and its application is severely restricted by available fabrication capabilities today. X-ray Fresnel lenses, both in cylindrical and linear forms, are proposed as superior focusing elements for hard X-rays. Their high efficiency, up to 100% in optimal construction, will enable us to manipulate beams with multiple lenses and obtain higher performance optics. Their design and fabrication are discussed in reference to those of X-ray Fresnel zone plates and micro Fresnel lenses for optoelectronics.

B.X. Yang

1993-01-01T23:59:59.000Z

226

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

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

Laboratory Directed Research and Development Program FY 2008 Annual Report  

E-Print Network [OSTI]

surveys dedicated to understanding the nature of dark energy,dark energy” driving the recent accelerated expansion. The next generation of surveys,Dark Energy with Weak Gravitational Lensing Alexie Leauthaud et al; “A Weak Lensing Study of X-ray Groups in the COSMOS Survey:

editor, Todd C Hansen

2009-01-01T23:59:59.000Z

229

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

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

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

232

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

233

Resolving a gravitational wave memory paradox  

E-Print Network [OSTI]

Two different approaches to gravitational perturbation theory appear to give two different answers for the properties of gravitational wave memory. We show that this contradiction is only apparent and the two approaches actually agree.

David Garfinkle; Istvan Racz

2014-06-20T23:59:59.000Z

234

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

235

Noncommutative spacetime effects and gravitation  

E-Print Network [OSTI]

In recent years Quantum Superstrings and Quantum Gravity approaches have come to rely on non differenciable spacetime manifolds. These throw up a noncommutative spacetime geometry and we consider the origin of mass and a related modification of the Dirac equation in this context. This also throws some light on gravitation itself.

B. G. Sidharth

2005-02-20T23:59:59.000Z

236

Electromagnetic weak turbulence theory revisited  

SciTech Connect (OSTI)

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

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

2012-10-15T23:59:59.000Z

237

27 contribution to weak electromagnetic decays  

Science Journals Connector (OSTI)

We notice that the assumption of octet dominance of the Cabibbo weak Hamiltonian is not required to explain the weak electromagnetic decays. In order to explain large asymmetry parameter ?(?+?p?) we consider ?7 contribution to the parity-violating Hamiltonian.

Ramesh C. Verma and M. P. Khanna

1978-12-01T23:59:59.000Z

238

Electronic publishing: strengths, weaknesses and threats  

Science Journals Connector (OSTI)

...April 1998 news News Electronic publishing: strengths, weaknesses and threats Derek McNally Treasurer of the RAS 2.7 April 1998 Vol 39 NEWS Both Monthly...Treasurer of the RAS. Electronic publishing: strengths, weaknesses and threats...

Derek McNally

1998-04-01T23:59:59.000Z

239

Gravitation in 2+1 dimensions  

Science Journals Connector (OSTI)

We investigate gravitational field theories in 2+1-spacetime dimensions. The consequences of the lack of a Newtonian limit to general relativity are reviewed. Further insight into the implications of this fact is gained by considering a new, general class of exact hydrostatic solutions. We show that all self-gravitating polytropic structures have the same gravitational mass and produce matter-filled spaces of finite spatial volume. Other theories of gravitation are also considered and the behavior of one such theory with a Newtonian limit is studied. Cosmological solutions of these gravitational theories are also studied in detail.

N. J. Cornish and N. E. Frankel

1991-04-15T23:59:59.000Z

240

KOI-3278: A Self-Lensing Binary Star System  

Science Journals Connector (OSTI)

...eclipsing binary. By modeling the pulse as gravitational...the Quasiperiodic Automated Transit Search algorithm (17) turned...The quasiperiodic automated transit search algorithm...Eggleton P. P. , Rapid binary star evolution for N-body simulations and population synthesis...

Ethan Kruse; Eric Agol

2014-04-18T23:59:59.000Z

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

Gravitational cooling of self-gravitating Bose-Condensates  

E-Print Network [OSTI]

Equilibrium configurations for a self-gravitating scalar field with self-interaction are constructed. The corresponding Schr\\"odinger-Poisson (SP) system is solved using finite differences assuming spherical symmetry. It is shown that equilibrium configurations of the SP system are late-time attractor solutions for initially quite arbitrary density profiles, which relax and virialize through the emission of scalar field bursts; a process dubbed gravitational cooling. Among other potential applications, these results indicate that scalar field dark matter models (in its different flavors) tolerate the introduction of a self-interaction term in the SP equations. This study can be useful in exploring models in which dark matter in galaxies is not point-like.

F. Siddhartha Guzman; L. Arturo Urena-Lopez

2006-03-22T23:59:59.000Z

242

Improved constraint on the primordial gravitational-wave density using recent cosmological data and its impact on cosmic string models  

E-Print Network [OSTI]

The production of a primordial stochastic gravitational-wave background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's evolutionary history. Probes like the Cosmic Microwave Background (CMB) or the Baryon Acoustic Oscillations (BAO) can be used to set upper limits on the stochastic gravitational-wave background energy density $\\Omega_{GW}$ for frequencies above $10^{-15}$ Hz. We perform a profile likelihood analysis of the Planck CMB temperature anisotropies and gravitational lensing data combined with WMAP low-$\\ell$ polarization, BAO, South Pole Telescope and Atacama Cosmology Telescope data. We find that $\\Omega_{GW}h_{0}^{2} strings, we have derived exclusion limits in the cosmic string parameter space. If the size of the loops is determined by gravitational back-reaction, string tension values lower than $\\sim 4 \\times 10^{-9}$ are excluded for a reconnection probability of $10^{-3}$.

Sophie Henrot-Versillé; Florent Robinet; Nicolas Leroy; Stéphane Plaszczynski; Nicolas Arnaud; Marie-Anne Bizouard; Fabien Cavalier; Nelson Christensen; François Couchot; Samuel Franco; Patrice Hello; Dominique Huet; Marie Kasprzack; Olivier Perdereau; Marta Spinelli; Matthieu Tristram

2014-08-22T23:59:59.000Z

243

Metrization in weakly sequential spaces  

E-Print Network [OSTI]

is a weakly sequential, T -space with an HCS-CP collection QU of open sets, then QV has finite order at every non-isolated point p in X. Proof: Let QU = (U : a c A) and let p be a non-isolated point in X. Let QU (p) (U c &U : p c U ). Suppose that a... neigh- borhood base QV = (V. : i t N) at p. Since QB (n) has finite order i at p, for each i c N, let pi E(ViA B. ) ? (p. : j & i) where Bi c i B (n), p is not an element of B. and B g B. , for j & i. Then 0 i i j' (p ) converges to p. Since each p...

Emerson, Dominique Margaret

2012-06-07T23:59:59.000Z

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

Dark energy, gravitation and supernovae  

E-Print Network [OSTI]

The discovery of the acceleration of the rate of expansion of the Universe fosters new explorations of the behavior of gravitation theories in the cosmological context. Either the GR framework is valid but a cosmic component with a negative equation of state is dominating the energy--matter contents or the Universe is better described at large by a theory that departs from GR. In this review we address theoretical alternatives that have been explored through supernovae.

Pilar Ruiz-Lapuente

2007-04-09T23:59:59.000Z

246

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

247

Non-Riemannian Gravitational Interactions  

E-Print Network [OSTI]

Recent developments in theories of non-Riemannian gravitational interactions are outlined. The question of the motion of a fluid in the presence of torsion and metric gradient fields is approached in terms of the divergence of the Einstein tensor associated with a general connection. In the absence of matter the variational equations associated with a broad class of actions involving non-Riemannian fields give rise to an Einstein-Proca system associated with the standard Levi-Civita connection.

Robin W Tucker; C Wang

1996-08-23T23:59:59.000Z

248

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

249

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

250

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

251

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

252

Gravitational wave experiments and Baksan project "OGRAN"  

E-Print Network [OSTI]

A brief sketch of the present status of gravitational wave experiments is given. Attention is concentrated to recent observations with the gravitational detector network. The project OGRAN for a combined optic-interferometrical and acoustical gravitation wave antenna planned for installation into underground facilities of the Baksan Neutrino Observatory is presented. We describe general principles of the apparatus, expected sensitivity and current characteristics of the antenna prototype; some ways for sensitivity improvement are also discussed.

L. Bezrukov; S. Popov; V. Rudenko; A. Serdobolskii; M. Skvortsov

2004-11-16T23:59:59.000Z

253

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

254

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

255

Adjudication of a Contract for the Supply of Pulsed Power Supplies for Correcting Lenses of the CERN Proton Synchroton (CPS)  

E-Print Network [OSTI]

Adjudication of a Contract for the Supply of Pulsed Power Supplies for Correcting Lenses of the CERN Proton Synchroton (CPS)

1974-01-01T23:59:59.000Z

256

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

257

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

258

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

259

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

260

WEAK MEASUREMENT IN QUANTUM MECHANICS ABRAHAM NEBEN  

E-Print Network [OSTI]

WEAK MEASUREMENT IN QUANTUM MECHANICS ABRAHAM NEBEN PHYS 342 Final Project March 10, 2011 Contents of Postselection 4 4. Impossible Spin Measurements 5 5. Hardy's Paradox 5 6. Controversy over Weak Measurement 8 7 of a Measurement of a Component of the Spin of a Spin-1/2 Particle Can Turn Out to be 100." [1] The topic

Rosner, Jonathan L.

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

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

262

Oph and the weak-wind problem  

Science Journals Connector (OSTI)

......but also in velocity space (Sundqvist...because of the wind clumpiness...line ratio maps of Sh 2-27...a clump of mass M cl located...candidate weak-wind stars (Martins...its space velocity of 30 km s1...the weak-wind problem...understanding the mass-loss mechanism...transverse velocity imply that......

V. V. Gvaramadze; N. Langer; J. Mackey

2012-11-01T23:59:59.000Z

263

CP Violation, Neutral Currents, and Weak Equivalence  

DOE R&D Accomplishments [OSTI]

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

Fitch, V. L.

1972-03-23T23:59:59.000Z

264

Gravitational waves versus cosmic strings  

Science Journals Connector (OSTI)

The equation which governs the temporal evolution of a gravitational wave (GW) in curved space-time can be treated as the Schrodinger equation for a particle moving in the presence of an effective potential. When GWs propagate in an expanding Universe with constant effective potential, there is a critical value (kc) of the comoving wave-number which discriminates the metric perturbations into oscillating (k > kc) and non-oscillating (k kc) modes. The effective potential is reduced to a non-vanishing constant in a cosmological model which is driven by a two-component fluid, consisting of radiation (dominant) and cosmic strings (subdominant). However, the cosmological evolution (gradually) results in the scaling of any long-cosmic-string network and, therefore, after some time (??) the Universe enters in the pure-radiation epoch. The evolution of the non-oscillatory GW modes during ??, results in the distortion of the low-frequency part of the stochastic GW power-spectrum, which, therefore, departs from scale invariance (anticipated in the pure-radiation case). As regards the corresponding high-frequency part (which is determined by the evolution of the oscillating modes), we find that the presence of cosmic strings gives rise to the quantum-gravitational creation of gravitons, leading to the amplification of the GW signal by (almost) two orders of magnitude.

Kostas Kleidis

2009-01-01T23:59:59.000Z

265

Testing Gravitational Physics with Superconducting Gravimeters  

Science Journals Connector (OSTI)

......being improved in geo- physics.29),30) Therefore...would fall at different rates towards the Sun and other...Testing Gravitational Physics with Superconducting...such dilatonic waves pass the Earth, because of...tests of gravitational physics in the previous sections......

Sachie Shiomi

2008-01-01T23:59:59.000Z

266

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

267

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

268

Dark matter in the Solar System. III. The distribution function of WIMPs at the Earth from gravitational capture  

Science Journals Connector (OSTI)

In this last paper in a series of three on weakly interacting massive particle (WIMP) dark matter in the Solar System, we focus on WIMPs bound to the system by gravitationally scattering off of planets. We present simulations of WIMP orbits in a toy solar system consisting of only the Sun and Jupiter. As previous work suggested, we find that the density of gravitationally captured WIMPs at the Earth is small and largely insensitive to the details of elastic scattering in the Sun. However, we find that the density of gravitationally captured WIMPs may be affected by external Galactic gravitational fields. If such fields are unimportant, the density of gravitationally captured WIMPs at the Earth should be similar to the maximum density of WIMPs captured in the Solar System by elastic scattering in the Sun. Using standard assumptions about the halo WIMP distribution function, we find that the gravitationally captured WIMPs contribute negligibly to direct detection event rates. While these WIMPs do dominate the annihilation rate of WIMPs in the Earth, the resulting event rate in neutrino telescopes is too low to be observed in next-generation neutrino telescopes.

Annika H. G. Peter

2009-05-28T23:59:59.000Z

269

Concentrated solar energy applications using Fresnel lenses: A review  

Science Journals Connector (OSTI)

Solar energy concentration technology using Fresnel lens is an effective way to make full use of sunlight. This paper makes a review about the recent development of the concentrated solar energy applications using Fresnel lenses. The ongoing research and development involves imaging systems and non-imaging systems. Compared with imaging systems, non-imaging systems have the merits of larger accept angles, higher concentration ratios with less volume and shorter focal length, higher optical efficiency, etc. Concentrated photovoltaics is a major application and the highest solar-to-electric conversion efficiency based on imaging Fresnel lens and non-imaging Fresnel lens are reported as over 30% and 31.5 ± 1.7%, respectively. Moreover, both kinds of systems are widely used in other fields such as hydrogen generation, photo-bio reactors as well as photochemical reactions, surface modification of metallic materials, solar lighting and solar-pumped laser. During the recent two decades, such applications have been built and tested successfully to validate the practicality of Fresnel lens solar concentration systems. Although the present application scale is small, the ongoing research and development works suggest that Fresnel lens solar concentrators, especially non-imaging Fresnel lenses, will bring a breakthrough of commercial solar energy concentration application technology in the near future. Finally, the advantages and disadvantages of two systems are also summarized.

W.T. Xie; Y.J. Dai; R.Z. Wang; K. Sumathy

2011-01-01T23:59:59.000Z

270

Strong lensing probability in TeVeS theory  

E-Print Network [OSTI]

We recalculate the strong lensing probability as a function of the image separation in TeVeS (tensor-vector-scalar) cosmology, which is a relativistic version of MOND (MOdified Newtonian Dynamics). The lens is modeled by the Hernquist profile. We assume an open cosmology with $\\Omega_b=0.04$ and $\\Omega_\\Lambda=0.5$ and three different kinds of interpolating functions. Two different galaxy stellar mass functions (GSMF) are adopted: PHJ (Panter-Heavens-Jimenez, 2004) determined from SDSS data release one and Fontana (Fontana et al., 2006) from GOODS-MUSIC catalog. We compare our results with both the predicted probabilities for lenses by Singular Isothermal Sphere (SIS) galaxy halos in LCDM (lambda cold dark matter) with Schechter-fit velocity function, and the observational results of the well defined combined sample of Cosmic Lens All-Sky Survey (CLASS) and Jodrell Bank/Very Large Array Astrometric Survey (JVAS). It turns out that the interpolating function $\\mu(x)=x/(1+x)$ combined with Fontana GSMF matches the results from CLASS/JVAS quite well.

Da-Ming Chen

2007-12-11T23:59:59.000Z

271

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

272

DECIGO: The Japanese space gravitational wave antenna  

Science Journals Connector (OSTI)

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a differential Fabry-Perot interferometer. We plan to launch DECIGO in middle of 2020s, after sequence of two precursor satellite missions, DECIGO pathfinder and Pre-DECIGO, for technology demonstration required to realize DECIGO and hopefully for detection of gravitational waves from our galaxy or nearby galaxies.

Shuichi Sato; Seiji Kawamura; Masaki Ando; Takashi Nakamura; Kimio Tsubono; Akito Araya; Ikkoh Funaki; Kunihito Ioka; Nobuyuki Kanda; Shigenori Moriwaki; Mitsuru Musha; Kazuhiro Nakazawa; Kenji Numata; Shin-ichiro Sakai; Naoki Seto; Takeshi Takashima; Takahiro Tanaka; Kazuhiro Agatsuma; Koh-suke Aoyanagi; Koji Arai; Hideki Asada; Yoichi Aso; Takeshi Chiba; Toshikazu Ebisuzaki; Yumiko Ejiri; Motohiro Enoki; Yoshiharu Eriguchi; Masa-Katsu Fujimoto; Ryuichi Fujita; Mitsuhiro Fukushima; Toshifumi Futamase; Katsuhiko Ganzu; Tomohiro Harada; Tatsuaki Hashimoto; Kazuhiro Hayama; Wataru Hikida; Yoshiaki Himemoto; Hisashi Hirabayashi; Takashi Hiramatsu; Feng-Lei Hong; Hideyuki Horisawa; Mizuhiko Hosokawa; Kiyotomo Ichiki; Takeshi Ikegami; Kaiki T Inoue; Koji Ishidoshiro; Hideki Ishihara; Takehiko Ishikawa; Hideharu Ishizaki; Hiroyuki Ito; Yousuke Itoh; Nobuki Kawashima; Fumiko Kawazoe; Naoko Kishimoto; Kenta Kiuchi; Shiho Kobayashi; Kazunori Kohri; Hiroyuki Koizumi; Yasufumi Kojima; Keiko Kokeyama; Wataru Kokuyama; Kei Kotake; Yoshihide Kozai; Hideaki Kudoh; Hiroo Kunimori; Hitoshi Kuninaka; Kazuaki Kuroda; Kei-ichi Maeda; Hideo Matsuhara; Yasushi Mino; Osamu Miyakawa; Shinji Miyoki; Mutsuko Y Morimoto; Tomoko Morioka; Toshiyuki Morisawa; Shinji Mukohyama; Shigeo Nagano; Isao Naito; Kouji Nakamura; Hiroyuki Nakano; Kenichi Nakao; Shinichi Nakasuka; Yoshinori Nakayama; Erina Nishida; Kazutaka Nishiyama; Atsushi Nishizawa; Yoshito Niwa; Taiga Noumi; Yoshiyuki Obuchi; Masatake Ohashi; Naoko Ohishi; Masashi Ohkawa; Norio Okada; Kouji Onozato; Kenichi Oohara; Norichika Sago; Motoyuki Saijo; Masaaki Sakagami; Shihori Sakata; Misao Sasaki; Takashi Sato; Masaru Shibata; Hisaaki Shinkai; Kentaro Somiya; Hajime Sotani; Naoshi Sugiyama; Yudai Suwa; Rieko Suzuki; Hideyuki Tagoshi; Fuminobu Takahashi; Kakeru Takahashi; Keitaro Takahashi; Ryutaro Takahashi; Ryuichi Takahashi; Tadayuki Takahashi; Hirotaka Takahashi; Takamori Akiteru; Tadashi Takano; Keisuke Taniguchi; Atsushi Taruya; Hiroyuki Tashiro; Yasuo Torii; Morio Toyoshima; Shinji Tsujikawa; Yoshiki Tsunesada; Akitoshi Ueda; Ken-ichi Ueda; Masayoshi Utashima; Yaka Wakabayashi; Hiroshi Yamakawa; Kazuhiro Yamamoto; Toshitaka Yamazaki; Jun'ichi Yokoyama; Chul-Moon Yoo; Shijun Yoshida; Taizoh Yoshino

2009-01-01T23:59:59.000Z

273

THE SL2S GALAXY-SCALE GRAVITATIONAL LENS SAMPLE. I. THE ALIGNMENT OF MASS AND LIGHT IN MASSIVE EARLY-TYPE GALAXIES AT z = 0.2-0.9  

SciTech Connect (OSTI)

We study the relative alignment of mass and light in a sample of 16 massive early-type galaxies at z = 0.2-0.9 that act as strong gravitational lenses. The sample was identified from deep multi-band images obtained as part of the Canada-France-Hawaii Telescope Legacy Survey and as part of the Strong Lensing Legacy Survey (SL2S). Higher resolution follow-up imaging is available for a subset of 10 systems. We construct gravitational lens models and infer total enclosed mass, elongation, and position angle of the mass distribution. By comparison with the observed distribution of light we infer that there is a substantial amount of external shear with mean value ({gamma}{sub ext}) = 0.12 {+-} 0.05, arising most likely from the environment of the SL2S lenses. In a companion paper, we combine these measurements with follow-up Keck spectroscopy to study the evolution of the stellar and dark matter content of early-type galaxies as a function of cosmic time.

Gavazzi, Raphaeel; Brault, Florence [Institut d'Astrophysique de Paris, UMR7095 CNRS-Universite Pierre et Marie Curie, 98bis bd Arago, F-75014 Paris (France); Treu, Tommaso; Marshall, Philip J. [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Ruff, Andrea [School of Physics, Astrophysics, University of Melbourne, Parkville 3010, Victoria (Australia)

2012-12-20T23:59:59.000Z

274

A NOVEL APPROACH IN THE WEAKLY INTERACTING MASSIVE PARTICLE QUEST: CROSS-CORRELATION OF GAMMA-RAY ANISOTROPIES AND COSMIC SHEAR  

SciTech Connect (OSTI)

Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.

Camera, Stefano [CENTRA, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Lisboa (Portugal); Fornasa, Mattia [School of Physics and Astronomy, University of Nottingham, Nottingham (United Kingdom); Fornengo, Nicolao; Regis, Marco [Dipartimento di Fisica, Universita di Torino and INFN, Torino (Italy)

2013-07-01T23:59:59.000Z

275

Quantum correlation cost of the weak measurement  

E-Print Network [OSTI]

Quantum correlation cost (QCC) characterizing how much quantum correlation is used in a weak-measurement process is presented based on the trace norm. It is shown that the QCC is related to the trace-norm-based quantum discord (TQD) by only a factor that is determined by the strength of the weak measurement, so it only catches partial quantumness of a quantum system compared with the TQD. We also find that the residual quantumness can be `extracted' not only by the further von Neumann measurement, but also by a sequence of infinitesimal weak measurements. As an example, we demonstrate our outcomes by the Bell-diagonal state.

Jun Zhang; Shao-xiong Wu; Chang-shui Yu

2014-09-14T23:59:59.000Z

276

 

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

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

277

DARK MATTER SUBSTRUCTURE DETECTION USING SPATIALLY RESOLVED SPECTROSCOPY OF LENSED DUSTY GALAXIES  

SciTech Connect (OSTI)

We investigate how strong lensing of dusty, star-forming galaxies (DSFGs) by foreground galaxies can be used as a probe of dark matter halo substructure. We find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters. In particular, we find that modeling of the full, three-dimensional (angular position and radial velocity) data can significantly facilitate substructure detection, increasing the sensitivity of observables to lower mass subhalos. We carry out simulations of lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix analysis to study the parameter degeneracies and mass detection limits of this method. We find that even with conservative assumptions, it is possible to detect galactic dark matter subhalos of {approx}10{sup 8} M{sub Sun} with high significance in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there is a {approx}55% probability of detecting a substructure with M > 10{sup 8} M{sub Sun} with more than 5{sigma} detection significance in each lens, if the abundance of substructure is consistent with previous lensing results. The full ALMA array, with its significantly enhanced sensitivity and resolution, should improve these estimates considerably. Given the sample of {approx}100 lenses provided by surveys such as the South Pole Telescope, our understanding of dark matter substructure in typical galaxy halos is poised to improve dramatically over the next few years.

Hezaveh, Yashar; Holder, Gilbert [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada)] [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Dalal, Neal [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)] [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Kuhlen, Michael [Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States)] [Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States); Marrone, Daniel [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)] [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Murray, Norman [CITA, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)] [CITA, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Vieira, Joaquin [California Institute of Technology, 1200 East California Blvd, MC 249-17, Pasadena, CA 91125 (United States)] [California Institute of Technology, 1200 East California Blvd, MC 249-17, Pasadena, CA 91125 (United States)

2013-04-10T23:59:59.000Z

278

Gravitational waves, diffusion and decoherence  

E-Print Network [OSTI]

The quite different behaviors exhibited by microscopic and macroscopic systems with respect to quantum interferences suggest that there may exist a naturally frontier between quantum and classical worlds. The value of the Planck mass (22$\\mu$g) may lead to the idea of a connection between this borderline and intrinsic fluctuations of spacetime. We show that it is possible to obtain quantitative answers to these questions by studying the diffusion and decoherence mechanisms induced on quantum systems by gravitational waves generated at the galactic or cosmic scales. We prove that this universal fluctuating environment strongly affects quantum interferences on macroscopic systems, while leaving essentially untouched those on microscopic systems. We obtain the relevant parameters which, besides the ratio of the system's mass to Planck mass, characterize the diffusion constant and decoherence time. We discuss the feasibility of experiments aiming at observing these effects in the context of ongoing progress towar...

Reynaud, Serge; Jaekel, Marc-Thierry

2008-01-01T23:59:59.000Z

279

BayesWave: Bayesian Inference for Gravitational Wave Bursts and Instrument Glitches  

E-Print Network [OSTI]

A central challenge in Gravitational Wave Astronomy is identifying weak signals in the presence of non-stationary and non-Gaussian noise. The separation of gravitational wave signals from noise requires good models for both. When accurate signal models are available, such as for binary Neutron star systems, it is possible to make robust detection statements even when the noise is poorly understood. In contrast, searches for "un-modeled" transient signals are strongly impacted by the methods used to characterize the noise. Here we take a Bayesian approach and introduce a multi-component, variable dimension, parameterized noise model that explicitly accounts for non-stationarity and non-Gaussianity in data from interferometric gravitational wave detectors. Instrumental transients (glitches) and burst sources of gravitational waves are modeled using a Morlet-Gabor continuous wavelet basis. The number and placement of the wavelets is determined by a trans-dimensional Reversible Jump Markov Chain Monte Carlo algorithm. The Gaussian component of the noise and sharp line features in the noise spectrum are modeled using the BayesLine algorithm, which operates in concert with the wavelet model.

Neil J. Cornish; Tyson B. Littenberg

2014-10-14T23:59:59.000Z

280

Superluminal neutrino: a quantum weak measurement effect?  

E-Print Network [OSTI]

Superluminal neutrino: a quantum weak measurement effect? Pragya Shukla · Dynamical laws, both in quantum and classical theory, are ?me-symmetric. · Measurements, the result of a measurement performed at a later ?me t1 or previous ?me

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

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.

282

Weak and Strong Theories of Truth  

Science Journals Connector (OSTI)

A subtheory of the theory of self-referential truth known as FS is shown to be weak as a theory of truth but equivalent to full FS in its...

Michael Sheard

2001-06-01T23:59:59.000Z

283

Amplification of Angular Rotations Using Weak Measurements  

E-Print Network [OSTI]

We present a weak measurement protocol that permits a sensitive estimation of angular rotations based on the concept of weak-value amplification. The shift in the state of a pointer, in both angular position and the conjugate orbital angular momentum bases, is used to estimate angular rotations. This is done by an amplification of both the real and imaginary parts of the weak-value of a polarization operator that has been coupled to the pointer, which is a spatial mode, via a spin-orbit coupling. Our experiment demonstrates the first realization of weak-value amplification in the azimuthal degree of freedom. We have achieved effective amplification factors as large as 100, providing a sensitivity that is on par with more complicated methods that employ quantum states of light or extremely large values of orbital angular momentum.

Omar S. Magana-Loaiza; Mohammad Mirhosseini; Brandon Rodenburg; Robert W. Boyd

2013-12-10T23:59:59.000Z

284

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

285

Testing gravitational physics with superconducting gravimeters  

E-Print Network [OSTI]

Superconducting gravimeters are the most sensitive instruments to measure surface gravity changes at low frequencies. Currently, about twenty five superconducting gravimeters are operating in the world and their global network has been developed. We investigate possible applications of the superconducting gravimeters to tests of gravitational physics. Previous experimental searches for spatial anisotropies in the gravitational constant G and for gravitational waves, performed with gravimeters in 1960's to 1970's, can be improved by applications of the current superconducting gravimeters. Also, we describe other proposed applications of testing the universality of free-fall and searching for composition-dependent dilatonic waves, and discuss future works necessary for these geophysical tests.

Sachie Shiomi

2009-02-24T23:59:59.000Z

286

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.

Buonanno, Alessandra

2014-01-01T23:59:59.000Z

287

Searching for gravitational waves from binary coalescence  

E-Print Network [OSTI]

We describe the implementation of a search for gravitational waves from compact binary coalescences in LIGO and Virgo data. This all-sky, all-time, multidetector search for binary coalescence has been used to search data ...

Vaulin, Ruslan

288

Tectonic signatures in coseismic gravitational energy change  

Science Journals Connector (OSTI)

......Same gravitational energy results are plotted with...Chile, Bolivia and Argentina. Energy gain (open circle...Bolivia, Chile and Argentina, near the central part...the subduction zones, energy gain is seen by systematic......

Toshiro Tanimoto; Taro Okamoto; Fabia Terra

2002-05-01T23:59:59.000Z

289

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

290

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

291

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

292

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

293

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

294

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

295

A comparison of the strong lensing properties of the Sersic and the NFW profiles  

E-Print Network [OSTI]

We investigate the strong lensing properties of the Sersic profile as an alternative to the NFW profile, focusing on applications to lens modelling of clusters. Given an underlying Sersic dark matter profile, we study whether an NFW profile can provide an acceptable fit to strong lensing constraints in the form of single or multiple measured Einstein radii. We conclude that although an NFW profile that fits the lensing constraints can be found in many cases, the derived parameters may be biased. In particular, we find that for n~2, which corresponds to massive clusters, the mass at r_200 of the best fit NFW is overestimated (by a factor of ~2) and the concentration is very low (c~2). The differences are important enough to warrant the inclusion of Sersic profile for future analysis of strong lensing clusters.

Árdís Elíasdóttir; Ole Möller

2007-06-22T23:59:59.000Z

296

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

297

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

298

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

299

Heat and Gravitation. III. Mixtures  

E-Print Network [OSTI]

The standard treatment of relativistic thermodynamics does not allow for a systematic treatment of mixtures. It is proposed that a formulation of thermodynamics as an action principle may be a suitable approach to adopt for a new investigation. This third paper of the series applies the action principle to a study of mixtures of ideal gases. The action for a mixture of ideal gases is the sum of the actions for the components, with an entropy that, in the absence of gravity, is determined by the Gibbs-Dalton hypothesis. Chemical reactions such as hydrogen dissociation are studied, with results that include the Saha equation and that are more complete than traditional treatments, especially so when gravitational effects are included. A mixture of two ideal gases is a system with two degrees of freedom and consequently it exhibits two kinds of sound. In the presence of gravity the Gibbs-Dalton hypothesis is modified to get results that agree with observation. The possibility of a parallel treatment of real gases is illustrated by an application to van der Waals gases. The overall conclusion is that experimental results serve to pin down the lagrangian in a very efficient manner. This leads to a convenient theoretical framework in which many dynamical problems can be studied.

Christian Fronsdal

2010-01-14T23:59:59.000Z

300

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...

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

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

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

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

302

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...

303

Strong side of weak topological insulators  

Science Journals Connector (OSTI)

Three-dimensional topological insulators are classified into “strong” (STI) and “weak” (WTI) according to the nature of their surface states. While the surface states of the STI are topologically protected from localization, this does not hold for the WTI. In this work, we show that the surface states of the WTI are actually protected from any random perturbation that does not break time-reversal symmetry, and does not close the bulk energy gap. Consequently, the conductivity of metallic surfaces in the clean system remains finite even in the presence of strong disorder of this type. In the weak disorder limit, the surfaces are found to be perfect metals, and strong surface disorder only acts to push the metallic surfaces inwards. We find that the WTI differs from the STI primarily in its anisotropy, and that the anisotropy is not a sign of its weakness but rather of its richness.

Zohar Ringel; Yaacov E. Kraus; Ady Stern

2012-07-02T23:59:59.000Z

304

Strong effects in weak nonleptonic decays  

SciTech Connect (OSTI)

In this report the weak nonleptonic decays of kaons and hyperons are examined with the hope of gaining insight into a recently proposed mechanism for the ..delta..I = 1/2 rule. The effective Hamiltonian for ..delta..S = 1 weak nonleptonic decays and that for K/sup 0/-anti K/sup 0/ mixing are calculated in the six-quark model using the leading logarithmic approximation. These are used to examine the CP violation parameters of the kaon system. It is found that if Penguin-type diagrams make important contributions to K ..-->.. ..pi pi.. decay amplitudes then upcoming experiments may be able to distinguish the six-quark model for CP violation from the superweak model. The weak radiative decays of hyperons are discussed with an emphasis on what they can teach us about hyperon nonleptonic decays and the ..delta..I = 1/2 rule.

Wise, M.B.

1980-04-01T23:59:59.000Z

305

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

306

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

Science Journals Connector (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 2 orders of magnitude better than current stationary constraints from the LAGEOS satellites.

Nicolás Yunes; Richard O’Shaughnessy; Benjamin J. Owen; Stephon Alexander

2010-09-14T23:59:59.000Z

307

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...

308

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

309

Learning discriminative localization from weakly labeled data  

Science Journals Connector (OSTI)

Visual categorization problems, such as object classification or action recognition, are increasingly often approached using a detection strategy: a classifier function is first applied to candidate subwindows of the image or the video, and then the ... Keywords: Discriminative discovery, Event detection, Image classification, Object detection, Time series classification, Weakly supervised learning

Minh Hoai; Lorenzo Torresani; Fernando De La Torre; Carsten Rother

2014-03-01T23:59:59.000Z

310

The Weak Interactions of the Muon  

Science Journals Connector (OSTI)

20 April 1965 research-article The Weak Interactions of the Muon R. H. Dalitz The Royal Society is collaborating with JSTOR to digitize, preserve, and extend access to Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences. www.jstor.org

1965-01-01T23:59:59.000Z

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

Measurement of pump-induced transient lensing in a cryogenically-cooled high average power Ti:sapphire amplifier  

Science Journals Connector (OSTI)

The transient thermal lensing in a liquid-nitrogren cooled kilohertz multipass amplifier is quantitatively measured with spatially-resolved Fourier transform spectral interferometry. A...

Planchon, Thomas A; Amir, Wafa; Childress, Colby; Squier, Jeff A; Durfee, Charles G

2008-01-01T23:59:59.000Z

313

Dark energy and matter evolution from lensing tomography  

Science Journals Connector (OSTI)

Reconstructed from lensing tomography, the evolution of the dark matter density field in the well-understood linear regime can provide model-independent constraints on the growth function of structure and the evolution of the dark energy density. We examine this potential in the context that high-redshift cosmology has in the future been fixed by cosmic microwave background measurements. We construct sharp tests for the existence of multiple dark matter components or a dark energy component that is not a cosmological constant. These functional constraints can be transformed into physically motivated model parameters. From the growth function, the fraction of the dark matter in a smooth component, such as a light neutrino, may be constrained to a statistical precision of ?(f)?0.0006fsky-1/2 by a survey covering a fraction of sky fsky with a redshift resolution ?z=0.1. For the dark energy, a parametrization in terms of the present energy density ?DE, equation of state w, and its redshift derivative w?, the constraints correspond to ?(w)=0.009fsky-1/2 and a degenerate combination of the other two parameters. For a fixed ?DE, ?(w?)=0.046fsky-1/2.

Wayne Hu

2002-10-30T23:59:59.000Z

314

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

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

1999-03-23T23:59:59.000Z

316

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

317

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

318

Analysis of Gravitational-Wave Data  

Science Journals Connector (OSTI)

The field of gravitational-wave data analysis has expanded greatly over the past decade and significant developments have been made in methods of analyzing the data taken by resonant bar and interferometric detectors, as well as analysis of mock LISA data. This book introduces much of the required theoretical background in gravitational physics, statistics and time series analysis before moving on to a discussion of gravitational-wave data analysis techniques themselves. The book opens with an overview of the theory of gravitational radiation, providing a comprehensive discussion of various introductory topics: linearized gravity, transverse traceless gauge, the effects of gravitational waves (via geodesic deviation), energy and momentum carried by the waves, and generation of gravitational waves. The second chapter provides an introduction to the various sources of gravitational waves, followed by more detailed expositions on some of the primary sources. For example, the description of compact binary coalescence is thorough and includes a brief exposition of the post-Newtonian formalism and the effective one body method. There also follows extended derivations of gravitational waves from distorted neutron stars, supernovae and a stochastic background. Chapter three provides an introduction to the statistical theory of signal detection, including a discussion of parameter estimation via the Fisher matrix formalism. This is presented from a very mathematical, postulate based, standpoint and I expect that even established gravitational-wave data analysts will find the derivations here more formal than they are used to. The discussion of likelihood ratio tests and the importance of prior probabilities are presented particularly clearly. The fourth chapter covers time series analysis, with power spectrum estimation, extraction of periodic signals and goodness of fit tests. Chapter five switches topics and gives the details of the response of gravitational-wave detectors. The derivation is kept general at the outset, so that a detailed discussion of the response of the LISA detector is possible, before restricting to the long wavelength approximation for discussion of ground based detectors. Chapter six provides a detailed exposition of the maximum likelihood method for searching for signals in Gaussian noise. Jaranowski and Królak developed the F-statistic search method, which has become standard in searches for continuous waves and is also used in LISA data analysis. Perhaps then, it is unsurprising that the discussion of matched filtering is couched in terms of a generalized F-statistic method. This chapter also covers parameter estimation via the Fisher matrix and applications to networks of detectors. As in other chapters, the initial formalism is rather general but, in later sections, specific examples are given, such as the application to continuous wave, compact binary coalescence and stochastic signals. The seventh, and final, chapter provides examples of concrete methods for analyzing data. The focus is on methods which the authors are most familiar with and consequently these are mostly relevant for the analysis of resonant bar data and searches for continuous wave signals. The discussion of complexities arising in creating banks of template waveforms is likely to be of more general interest. The last two chapters of the book, which contain the meat of the subject of gravitational-wave data analysis, are regrettably short. Several large research areas are not discussed at all, including: time–frequency excess power search methods; Bayesian parameter estimation techniques (e.g. Markov Chain Monte Carlo) to go past the Fisher matrix approximation; signal consistency tests and other methods of dealing with non-Gaussian data. On the back cover, it states that `this book introduces researchers entering the field ... to gravitational-wave data analysis'. While this book certainly does contain much of the necessary introductory material, the presentation will likely prove too technical to be easily accessible to beginn

Stephen Fairhurst

2010-01-01T23:59:59.000Z

319

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

320

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 than in vacuum, 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 very 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

2014-04-28T23:59:59.000Z

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


321

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

322

New Perspectives On the Relevance of Gravitation for the Covariant Description of Electromagnetically Polarizable Media  

E-Print Network [OSTI]

Electromagnetic properties of a simple polarisable medium may be parameterised in terms of a constitutive tensor whose properties can in principle be determined by experiments in non-inertial (accelerating) frames and in the presence of weak but variable gravitational fields. After establishing some geometric notation, discussion is given to basic concepts of stress, energy and momentum in the vacuum where the useful notion of a drive form is introduced in order to associate the conservation of currents involving the flux of energy, momentum and angular momentum with spacetime isometries. The definition of the stress-energy-momentum tensor is discussed with particular reference to its symmetry based on its role as a source of relativistic gravitation. General constitutive properties of material continua are formulated in terms of spacetime tensors including those that describe magneto-electric phenomena in moving media. This leads to a formulation of a self-adjoint constitutive tensor describing, in general, inhomogeneous, anisotropic, magneto-electric bulk matter in arbitrary motion. The question of an invariant characterisation of intrinsically magneto-electric media is explored. An action principle is established to generate the phenomenological Maxwell system and the use of variational derivatives to calculate stress-energy-momentum tensors is discussed in some detail. The relation of this result to tensors proposed by Abraham and others is discussed in the concluding section where the relevance of the whole approach to experiments on matter in non-inertial environments with variable gravitational and electromagnetic fields is stressed.

T. Dereli; J. Gratus; R. W. Tucker

2006-10-27T23:59:59.000Z

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

Joint galaxy-lensing observables and the dark energy  

Science Journals Connector (OSTI)

Deep multicolor galaxy surveys with photometric redshifts will provide a large number of two-point correlation observables: galaxy-galaxy angular correlations, galaxy-shear cross correlations, and shear-shear correlations between all redshifts. These observables can potentially enable a joint determination of the dark-energy-dependent evolution of the dark matter and distances as well as the relationship between galaxies and dark matter halos. With recent cosmic microwave background determinations of the initial power spectrum, a measurement of the mass clustering at even a single redshift will constrain a well-specified combination of dark energy (DE) parameters in a flat universe; we provide convenient fitting formulas for such studies. The combination of galaxy-shear and galaxy-galaxy correlations can determine this amplitude at multiple redshifts. We illustrate this ability in a description of the galaxy clustering with 5 free functions of redshift which can be fitted from the data. The galaxy modeling is based on a mapping onto halos of the same abundance that models a flux-limited selection. In this context and under a flat geometry, a 4000 deg2 galaxy-lensing survey can achieve a statistical precision of ?(?DE)=0.005 for the dark energy density, ?(wDE)=0.02 and ?(wa)=0.17 for its equation of state and evolution, evaluated at dark energy matter equality z?0.4, as well as constraints on the 5 halo functions out to z=1. More importantly, a joint analysis can make dark energy constraints robust against systematic errors in the shear-shear correlation and halo modeling.

Wayne Hu and Bhuvnesh Jain

2004-08-26T23:59:59.000Z

325

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

326

Helicity Observation of Weak and Strong Fields  

E-Print Network [OSTI]

We report in this letter our analysis of a large sample of photospheric vector magnetic field measurements. Our sample consists of 17200 vector magnetograms obtained from January 1997 to August 2004 by Huairou Solar Observing Station of the Chinese National Astronomical Observatory. Two physical quantities, $\\alpha$ and current helicity, are calculated and their signs and amplitudes are studied in a search for solar cycle variations. Different from other studies of the same type, we calculate these quantities for weak ($100G1000G$) fields separately. For weak fields, we find that the signs of both $\\alpha$ and current helicity are consistent with the established hemispheric rule during most years of the solar cycle and their magnitudes show a rough tendency of decreasing with the development of solar cycle. Analysis of strong fields gives an interesting result: Both $\\alpha$ and current helicity present a sign opposite to that of weak fields. Implications of these observations on dynamo theory and helicity production are also briefly discussed.

Mei Zhang

2006-06-09T23:59:59.000Z

327

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

328

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

329

Relic gravitational waves and the generalized second law  

SciTech Connect (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.

Izquierdo, German; Pavon, Diego [Departamento de Fisica, Universidad Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)

2004-12-15T23:59:59.000Z

330

The effects of the RHIC E-lenses magnetic structure layout on the proton beam trajectory  

SciTech Connect (OSTI)

We are designing two electron lenses (E-lens) to compensate for the large beam-beam tune spread from proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). They will be installed in RHIC IR10. First, the layout of these two E-lenses is introduced. Then the effects of e-lenses on proton beam are discussed. For example, the transverse fields of the e-lens bending solenoids and the fringe field of the main solenoids will shift the proton beam. For the effects of the e-lens on proton beam trajectory, we calculate the transverse kicks that the proton beam receives in the electron lens via Opera at first. Then, after incorporating the simplified E-lens lattice in the RHIC lattice, we obtain the closed orbit effect with the Simtrack Code.

Gu, X.; Pikin, A.; Luo, Y.; Okamura, M.; Fischer, W.; Gupta, R.; Hock, J.; Raparia, D.

2011-03-28T23:59:59.000Z

331

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

332

Phase Transition in a Model Gravitating System  

Science Journals Connector (OSTI)

We present recent developments in the study of an interacting gravitational system of concentric, spherical, mass shells. The existence of two distinct phases is demonstrated. The nature of the transition in the microcanonical, canonical, and grand canonical ensembles is studied both theoretically in terms of mean field theory and via dynamical simulation. Striking differences are found in each environment, especially the last.

Bruce N. Miller and Paige Youngkins

1998-11-30T23:59:59.000Z

333

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

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

An optical time-delay estimate for the double gravitational lens system B1600+434  

E-Print Network [OSTI]

We present optical I-band light curves of the gravitationally lensed double QSO B1600+434 from observations obtained at the Nordic Optical Telescope (NOT) between April 1998 and November 1999. The photometry has been performed by simultaneous deconvolution of all the data frames, involving a numerical lens galaxy model. Four methods have been applied to determine the time delay between the two QSO components, giving a mean estimate of \\Delta_t = 51+/-4 days (95% confidence level). This is the fourth optical time delay ever measured. Adopting a Omega=0.3, Lambda=0 Universe and using the mass model of Maller et al. (2000), this time-delay estimate yields a Hubble parameter of H_0=52 (+14, -8) km s^-1 Mpc^-1 (95% confidence level) where the errors include time-delay as well as model uncertainties. There are time-dependent offsets between the two (appropriately shifted) light curves that indicate the presence of external variations due to microlensing.

I. Burud; J. Hjorth; A. O. Jaunsen; M. I. Andersen; H. Korhonen; J. W. Clasen; J. Pelt; F. P. Pijpers; P. Magain; R. OEstensen

2000-07-11T23:59:59.000Z

337

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

338

An investigation of the effect of permeable and impermeable lenses on well performance  

E-Print Network [OSTI]

= 6. 000 INCHES RADIUS OF WELL. = 0 ' 095 INCHES RATH TEMPERATURE = 149 ' 9 DEGREFS F THICKNESS OF MODEL = 0 ' 345 INCHES INITIAL TEMPFRATURE = 76 ' 8 DEGREES F THICKNESS OF LENSE = 0 ~ IZ5 INCHES TIME SEC 0025 0 ' 5 1 ~ 0 TEMPERATURE fDEGREE 1... RADIUS OF WELL ~ 0 ~ 095 INCHES RATH TEMPERATURE = 149 ~ 8 DEGREES F THICKNESS OF MODEL = 0 ~ 420 INCHES INITIAL TEMPERATURE = 76 ~ 5 DEGREES F THICKNESS OF LENSE = 0 125 INCHES TIME SEC 0 ' 25 0 ' 5 I ~ 0 TEMPERATURE ( DEGREES F ) FOR RADU...

Miesch, Edward Peter

2012-06-07T23:59:59.000Z

339

A comparison of weak-turbulence and PIC simulations of weak electron-beam plasma interaction  

E-Print Network [OSTI]

Quasilinear theory has long been used to treat the problem of a weak electron beam interacting with plasma and generating Langmuir waves. Its extension to weak-turbulence theory treats resonant interactions of these Langmuir waves with other plasma wave modes, in particular ion-sound waves. These are strongly damped in plasma of equal ion and electron temperatures, as sometimes seen in, for example, the solar corona and wind. Weak turbulence theory is derived in the weak damping limit, with a term describing ion-sound wave damping then added. In this paper we use the EPOCH particle-in-cell code to numerically test weak turbulence theory for a range of electron-ion temperature ratios. We find that in the cold ion limit the results agree well, but increasing ion temperature the three-wave resonance becomes broadened in proportion to the ion-sound wave damping rate. This may be important in, for example, the theory of solar radio bursts, where the spectrum of Langmuir waves is critical. Additionally we establish...

Ratcliffe, Heather; Rozenan, Mohammed B Che; Nakariakov, Valery

2014-01-01T23:59:59.000Z

340

Q-weak: First Direct Measurement of the Weak Charge of the Proton  

E-Print Network [OSTI]

The Q-weak experiment at Hall C of Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton, Qweak(p), through a precision measurement of the parity-violating asymmetry in elastic e-p scattering at low momentum transfer Q^2= 0.025 (GeV/c)^2 with incident electron beam energy of 1.155 GeV. The Q-weak experiment, along with earlier results of parity violating elastic scattering experiments, is expected to determine the most precise value of Qweak(p) which is suppressed in the Standard Model. If this result is further combined with the 133Cs atomic parity violation (APV) measurement, significant constraints on the weak charge of the up quark, down quark, and neutron can be extracted. This data will also be used to determine the weak-mixing angle, sin^2 theta_?W, with a relative uncertainty of < 0.5% that will provide a competitive measurement of the running of sin^2 theta_?W to low Q^2. An overview of the experiment and its results using the commissioning dataset, constituting approximately 4% of the data collected in the experiment, are reported here.

Nuruzzaman

2013-12-20T23:59:59.000Z

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

Nuclear magnetic resonances in weak fields  

E-Print Network [OSTI]

first choax@ation of nuclear resonances in weak f le). de was sade by k 0, S~ in fiel4u of 6 and lg gauss using a sanple siue of. 1 liter, The nagnetic fields were produced in a solenoi4 pou?x?d by a bazdz of lead storage batteriesx an4 the resonances..., Tbe poser was pxovided for the static nagnetic field by a bank of 20 lead storage cells connected in ssriesi The current was a+usted to the desired value with a variable xesistanoe which was connected in sex'ies with the solenoid. Qm source of field...

Mitchell, Richard Warren

2012-06-07T23:59:59.000Z

342

Contradiction and grammar : the case of weak islands  

E-Print Network [OSTI]

This thesis is about weak islands. Weak islands are contexts that are transparent to some but not all operator-variable dependencies. For this reason, they are also sometimes called selective islands. Some paradigmatic ...

Abrusán, Márta

2007-01-01T23:59:59.000Z

343

Weak Values and Direct Measurement of the Quantum Wavefunction  

Science Journals Connector (OSTI)

We review recent work showing that weak values and weak measurements can be used to perform certain measurements with unprecedented accuracy and moreover can be used to perform a...

Boyd, Robert W

344

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

345

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

346

Discovery of Four Doubly Imaged Quasar Lenses from the Sloan Digital Sky Survey  

E-Print Network [OSTI]

We report the discovery of four doubly imaged quasar lenses. All the four systems are selected as lensed quasar candidates from the Sloan Digital Sky Survey data. We confirm their lensing hypothesis with additional imaging and spectroscopic follow-up observations. The discovered lenses are SDSS J0743+2457 with the source redshift z_s=2.165, the lens redshift z_l=0.381, and the image separation theta=1.034", SDSS J1128+2402 with z_s=1.608 and theta=0.844", SDSS J1405+0959 with z_s=1.810, z_l~0.66, and theta=1.978", and SDSS J1515+1511 with z_s=2.054, z_l=0.742, and theta=1.989". It is difficult to estimate the lens redshift of SDSS J1128+2402 from the current data. Two of the four systems (SDSS J1405+0959 and SDSS J1515+1511) are included in our final statistical lens sample to derive constraints on dark energy and the evolution of massive galaxies.

Inada, Naohisa; Rusu, Cristian E; Kayo, Issha; Morokuma, Tomoki

2014-01-01T23:59:59.000Z

347

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.

348

Effects of protein, mucin, and human tears on adherence of Pseudomonas aeruginosa to hydrophilic contact lenses.  

Science Journals Connector (OSTI)

...characteristics on the attachment of a marine pseudomonad to solid surfaces...associated with contact lens wear. Arch. Ophthalmol. 102...1986. The eye in contact lens wear, p. 22-50. Butterworths...aphakic eyes with extended-wear lenses. Ophthalmology 91...

M J Miller; L A Wilson; D G Ahearn

1988-03-01T23:59:59.000Z

349

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

350

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

E-Print Network [OSTI]

between the ice and matrix surfaces produce a diverse array of behavior, including the growth of needleFormation of ice lenses and frost heave A. W. Rempel1 Received 13 April 2006; revised 26 January 2007; accepted 8 March 2007; published 21 June 2007. [1] I examine the morphology of ice growth

Rempel, Alan W.

351

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.

352

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

353

Self Creation Cosmology - An Alternative Gravitational Theory  

E-Print Network [OSTI]

The premature acceptance of the standard cosmological model, the 'LambdaCDM' paradigm, is questioned; Self Creation Cosmology is offered as an alternative and shown to be as equally concordant with observed cosmological constraints and local observations including the EEP. The Brans Dicke theory is modified to enable the creation of matter and energy out of the self contained gravitational and scalar fields constrained by the local conservation of energy so that rest masses vary whereas the observed Newtonian Gravitation 'constant' does not. There is a conformal equivalence between self-creation and General Relativity in vacuo, which results in the predictions of the two theories being equal in the standard tests. In self-creation test particles in vacuo follow the geodesics of General Relativity. Nevertheless there are three types of experiment, including the LIGO apparatus, which are able to distinguish between the two theories. Self-creation is as consistent with cosmological constraints in the distant sup...

Barber, G A

2004-01-01T23:59:59.000Z

354

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

355

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

356

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

357

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

358

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

359

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

360

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

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

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

2009-08-03T23:59:59.000Z

362

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

363

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

364

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

365

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

366

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

367

Detection of large-scale intrinsic ellipticity—density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveys  

Science Journals Connector (OSTI)

......Gunn J. E., Ivezic z., Knapp G. R., Kent S., Yasuda N., 2001, inHarnden F. R. Jr., Primini F. A., Payne H. E...0506614). MacGillivray H. T. , Dodd R. J., McNally B. V., Corwin H. G., 1982......

Rachel Mandelbaum; Christopher M. Hirata; Mustapha Ishak; Uros Seljak; Jonathan Brinkmann

368

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

369

Weak interaction studies using resonance ionization spectroscopy  

SciTech Connect (OSTI)

Important developments in laser sources for the vacuum ultraviolet (VUV) region of the spectrum are making it possible to carry out resonance ionization of some of the noble gases. It has already been shown that xenon can be ionized in a two-photon allowed excitation from the ground state. Recently a new method of generating radiation by four-wave mixing in mercury vapor enables excitation of xenon in a one-photon resonance process. With these new laser sources we expect to have effective ionization volumes of 10/sup -3/ to 10/sup -2/ cm/sup 3/ for the cases of argon, krypton, and xenon. This has important consequences in weak interaction physics and environmental research.

Payne, M.G.; Hurst, G.S.

1982-01-01T23:59:59.000Z

370

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

371

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

372

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

373

Gravitational radiation from rotating monopole-string systems  

E-Print Network [OSTI]

We study the gravitational radiation from a rotating monopole-antimonopole pair connected by a string. While at not too high frequencies the emitted gravitational spectrum is described asymptotically by $P_n\\propto n^{-1}$, the spectrum is exponentially suppressed in the high-frequency limit, $P_n\\propto \\exp(-n/n_{\\rm cr})$. Below $n_{\\rm cr}$, the emitted spectrum of gravitational waves is very similar to the case of an oscillating monopole pair connected by a string, and we argue therefore that the spectrum found holds approximately for any moving monopole-string system. As application, we discuss the stochastic gravitational wave background generated by monopole-antimonopole pairs connected by strings in the early Universe and gravitational wave bursts emitted at present by monopole-string networks. We confirm that advanced gravitational wave detectors have the potential to detect a signal for string tensions as small as $G\\mu\\sim 10^{-13}$.

E. Babichev; V. Dokuchaev; M. Kachelriess

2004-11-30T23:59:59.000Z

374

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

375

Gravitational-Wave Stochastic Background from Cosmic Strings  

Science Journals Connector (OSTI)

We consider the stochastic background of gravitational waves produced by a network of cosmic strings and assess their accessibility to current and planned gravitational wave detectors, as well as to big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and pulsar timing constraints. We find that current data from interferometric gravitational wave detectors, such as Laser Interferometer Gravitational Wave Observatory (LIGO), are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds. Future more sensitive LIGO runs and interferometers such as Advanced LIGO and Laser Interferometer Space Antenna (LISA) will be able to explore substantial parts of the parameter space.

Xavier Siemens; Vuk Mandic; Jolien Creighton

2007-03-13T23:59:59.000Z

376

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

377

Using the Uncharged Kerr Black Hole as a Gravitational Mirror  

Science Journals Connector (OSTI)

We extend the study of the possible use of the Schwarzschild black hole as a gravitational mirror to the more general case of an...

Claes R. Cramer

1997-04-01T23:59:59.000Z

378

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

379

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

380

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

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 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

382

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

E-Print Network [OSTI]

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

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

2013-06-24T23:59:59.000Z

383

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

E-Print Network [OSTI]

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

Aghion, S; Amsler, C; Ariga, A; Ariga, T; Belov, A S; Bonomi, G; Br?unig, P; Bremer, J; Brusa, R S; Cabaret, L; Canali, C; Caravita, R; Castelli, F; Cerchiari, G; Cialdi, S; Comparat, D; Consolati, G; Derking, J H; Di Domizio, S; Di Noto, L; Doser, M; Dudarev, A; Ereditato, A; Ferragut, R; Fontana, A; Genova, P; Giammarchi, M; Gligorova, A; Gninenko, S N; Haider, S; Harasimovicz, J; Hogan, S D; Huse, T; Jordan, E; J?rgensen, L V; Kaltenbacher, T; Kawada, J; Kellerbauer, A; Kimura, M; Knecht, A; Krasnick?, D; Lagomarsino, V; Magnani, A; Mariazzi, S; Matveev, V A; Moia, F; Nebbia, G; N?d?lec, P; Oberthaler, M K; Pacifico, N; Petr?cek, V; Pistillo, C; Prelz, F; Prevedelli, M; Regenfus, C; Riccardi, C; R?hne, O; Rotondi, A; Sandaker, H; Scampoli, P; Sosa, A; Storey, J; Subieta Vasquez, M.A; ?pacek, M; Testera, G; Trezzi, D; Vaccarone, R; Welsch, C P; Zavatarelli, S

2013-01-01T23:59:59.000Z

384

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

385

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

386

Does gravitational collapse lead to singularities?  

E-Print Network [OSTI]

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

Ernst Fischer

2013-03-23T23:59:59.000Z

387

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

388

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

389

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

390

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

391

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

392

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

393

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

394

CP-odd weak basis invariants and texture zeros  

Science Journals Connector (OSTI)

We construct the CP-odd weak basis invariants from the neutrino mass matrix in a weak basis, in which the charged lepton mass matrix is diagonal, and find the necessary and sufficient conditions for CP conservation. We study the interrelationships between different CP-odd weak basis invariants to examine their implications for the Dirac- and Majorana-type CP violating phases for the phenomenologically allowed Frampton-Glashow-Marfatia texture zero structures of the neutrino mass matrix.

S. Dev; Sanjeev Kumar; Surender Verma

2009-02-20T23:59:59.000Z

395

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

396

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

397

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

398

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

399

Weak and Strong Superiorization: Between Feasibility-Seeking and ...  

E-Print Network [OSTI]

Sep 30, 2014 ... This does not create any ambiguity because whether we consider an ... A fundamental difference between weak and strong superiorization lies.

User

2014-10-01T23:59:59.000Z

400

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

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.


401

Discovery of A Very Bright, Strongly-Lensed z=2 Galaxy in the SDSS DR5  

SciTech Connect (OSTI)

We report on the discovery of a very bright z = 2.00 star-forming galaxy that is strongly lensed by a foreground z = 0.422 luminous red galaxy (LRG). This system was found in a systematic search for bright arcs lensed by LRGs and brightest cluster galaxies in the Sloan Digital Sky Survey Data Release 5 sample. Follow-up observations on the Subaru 8.2m telescope on Mauna Kea and the Astrophysical Research Consortium 3.5m telescope at Apache Point Observatory confirmed the lensing nature of this system. A simple lens model for the system, assuming a singular isothermal ellipsoid mass distribution, yields an Einstein radius of {theta}{sub Ein} = 3.82 {+-} 0.03{double_prime} or 14.8 {+-} 0.1h{sup -1} kpc at the lens redshift. The total projected mass enclosed within the Einstein radius is 2.10 {+-} 0.03 x 10{sup 12}h{sup -1}M{sub {circle_dot}}, and the magnification factor for the source galaxy is 27 {+-} 1. Combining the lens model with our gVriz photometry, we find an (unlensed) star formation rate for the source galaxy of 32 h{sup -1} M{sub {circle_dot}} hr{sup -1}, adopting a fiducial constant star formation rate model with an age of 100 Myr and E(B-V) = 0.25. With an apparent magnitude of r = 19.9, this system is among the very brightest lensed z {ge} 2 galaxies, and provides an excellent opportunity to pursue detailed studies of the physical properties of an individual high-redshift star-forming galaxy.

Lin, Huan; Buckley-Geer, Elizabeth; /Fermilab; Allam, Sahar S.; /Fermilab /Wyoming U.; Tucker, Douglas L.; Diehl, H.Thomas; Kubik, Donna; Kubo, Jeffrey M.; Annis, James; /Fermilab; Frieman, Joshua A.; /Chicago U., Astron. Astrophys. Ctr. /Fermilab /KICP, Chicago; Oguri, Masamune; /KIPAC, Menlo Park; Inada, Naohisa; /Wako, RIKEN

2008-09-30T23:59:59.000Z

402

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

403

Astrophysical model selection in gravitational wave astronomy  

Science Journals Connector (OSTI)

Theoretical studies in gravitational wave astronomy have mostly focused on the information that can be extracted from individual detections, such as the mass of a binary system and its location in space. Here we consider how the information from multiple detections can be used to constrain astrophysical population models. This seemingly simple problem is made challenging by the high dimensionality and high degree of correlation in the parameter spaces that describe the signals, and by the complexity of the astrophysical models, which can also depend on a large number of parameters, some of which might not be directly constrained by the observations. We present a method for constraining population models using a hierarchical Bayesian modeling approach which simultaneously infers the source parameters and population model and provides the joint probability distributions for both. We illustrate this approach by considering the constraints that can be placed on population models for galactic white dwarf binaries using a future space-based gravitational wave detector. We find that a mission that is able to resolve ?5000 of the shortest period binaries will be able to constrain the population model parameters, including the chirp mass distribution and a characteristic galaxy disk radius to within a few percent. This compares favorably to existing bounds, where electromagnetic observations of stars in the galaxy constrain disk radii to within 20%.

Matthew R. Adams; Neil J. Cornish; Tyson B. Littenberg

2012-12-18T23:59:59.000Z

404

Astrophysical Model Selection in Gravitational Wave Astronomy  

E-Print Network [OSTI]

Theoretical studies in gravitational wave astronomy have mostly focused on the information that can be extracted from individual detections, such as the mass of a binary system and its location in space. Here we consider how the information from multiple detections can be used to constrain astrophysical population models. This seemingly simple problem is made challenging by the high dimensionality and high degree of correlation in the parameter spaces that describe the signals, and by the complexity of the astrophysical models, which can also depend on a large number of parameters, some of which might not be directly constrained by the observations. We present a method for constraining population models using a Hierarchical Bayesian modeling approach which simultaneously infers the source parameters and population model and provides the joint probability distributions for both. We illustrate this approach by considering the constraints that can be placed on population models for galactic white dwarf binaries using a future space based gravitational wave detector. We find that a mission that is able to resolve ~5000 of the shortest period binaries will be able to constrain the population model parameters, including the chirp mass distribution and a characteristic galaxy disk radius to within a few percent. This compares favorably to existing bounds, where electromagnetic observations of stars in the galaxy constrain disk radii to within 20%.

Matthew Adams; Neil Cornish; Tyson Littenberg

2012-09-27T23:59:59.000Z

405

An Atomic Gravitational Wave Interferometric Sensor (AGIS)  

SciTech Connect (OSTI)

We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline {approx} 1 km can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline {approx} 1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity {approx} 10{sup -20}/{radical}Hz. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.

Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.; Rajendran, Surjeet; /SLAC /Stanford U., Phys. Dept.

2008-08-01T23:59:59.000Z

406

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

407

Evolutionary-algorithm-based analysis of gravitational microlensing light curves  

Science Journals Connector (OSTI)

......results of Vermaak ( , ); they cover most of the lensing zone, and...fitting binary light curves Given a set of parameters, obtaining the...priors that avoid hard limits - to cover cases where the secondary lens...the general algorithm otherwise set-up in much the same way as......

V. Rajpaul

2012-12-01T23:59:59.000Z

408

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

409

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

410

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

411

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

412

A prototype classifier based on gravitational search algorithm  

Science Journals Connector (OSTI)

In recent years, heuristic algorithms have been successfully applied to solve clustering and classification problems. In this paper, gravitational search algorithm (GSA) which is one of the newest swarm based heuristic algorithms is used to provide a ... Keywords: Classification, Gravitational search algorithm, Prototype classifier, Swarm intelligence, UCI machine learning repository

Abbas Bahrololoum; Hossein Nezamabadi-pour; Hamid Bahrololoum; Masoud Saeed

2012-02-01T23:59:59.000Z

413

New Equation and Energy-Tensor of a Gravitational Field  

Science Journals Connector (OSTI)

......some critical value. The energy- of the gravitational...is shown that the total energy can always be transformed...it easy to compute the energy of an isolated system...Gravitation-Held A., ed. (1980) New York: Plenum. 329. 5) cf......

Ryoyu Utiyama

1984-07-01T23:59:59.000Z

414

 

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

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

415

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

416

Gravitationally Induced Particle Production: Thermodynamics and Kinetic Theory  

E-Print Network [OSTI]

A relativistic kinetic description for the irreversible thermodynamic process of gravitationally induced particle production is proposed in the context of an expanding Friedmann-Robertson-Walker (FRW) geometry. We show that the covariant thermodynamic treatment referred to as "adiabatic" particle production provoked by the cosmic time-varying gravitational field has a consistent kinetic counterpart. The variation of the distribution function is associated to a non-collisional kinetic term of quantum-gravitational origin which is proportional to the ratio $\\Gamma/H$, where $\\Gamma$ is the gravitational particle production rate and H is the Hubble parameter. For $\\Gamma << H$ the process is negligible and as should be expected it also vanishes (regardless of the value of $\\Gamma$) in the absence of gravitation. The resulting non-equilibrium distribution function has the same functional form of equilibrium with the evolution laws corrected by the particle production process. The macroscopic temperature evo...

Lima, J A S

2014-01-01T23:59:59.000Z

417

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

418

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

419

Astrophysical Model Selection in Gravitational Wave Astronomy  

E-Print Network [OSTI]

Theoretical studies in gravitational wave astronomy have mostly focused on the information that can be extracted from individual detections, such as the mass of a binary system and its location in space. Here we consider how the information from multiple detections can be used to constrain astrophysical population models. This seemingly simple problem is made challenging by the high dimensionality and high degree of correlation in the parameter spaces that describe the signals, and by the complexity of the astrophysical models, which can also depend on a large number of parameters, some of which might not be directly constrained by the observations. We present a method for constraining population models using a Hierarchical Bayesian modeling approach which simultaneously infers the source parameters and population model and provides the joint probability distributions for both. We illustrate this approach by considering the constraints that can be placed on population models for galactic white dwarf binaries ...

Adams, Matthew; Littenberg, Tyson

2012-01-01T23:59:59.000Z

420

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

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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421

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

422

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

423

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

424

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

425

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

426

Speed of Light in Gravitational Fields  

E-Print Network [OSTI]

A spherically symmetric and static metric that describes physical coordinates is introduced. It is defined to be a metric that gives coordinate independent results for physically observable quantities without a further coordinate transformation. The suggested metric also makes a prediction for the second order gravitational red shift effect that can be utilized for a precision experimental test in the future. A possible new experimental test would be provided by a modern Michelson Morley experiment on the earth with the two arms in vertical and horizontal directions to see the validity of isotropy or anisotropy for the speed of light. The possibility of using pulsars and GPS (Global Positioning System) for a general relativity test is discussed.

Yukio Tomozawa

2003-03-03T23:59:59.000Z

427

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

428

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

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

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

431

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

432

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

433

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

434

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

435

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

436

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

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

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

437

Momentum broadening in weakly coupled quark-gluon plasma  

E-Print Network [OSTI]

We calculate the probability distribution P(k [subscript ?]) for the momentum perpendicular to its original direction of motion that an energetic quark or gluon picks up as it propagates through weakly coupled quark-gluon ...

D'Eramo, F.

438

Inversion for elastic parameters in weakly anisotropic media  

Science Journals Connector (OSTI)

......propagation in inhomogeneous weakly anisotropic elastic media, J. geophys...2001. Ray tracing in anisotropic media with singularities...Measured anisotropy in Pierre shale, Geophys. Prospect., 31...approximation of ray theory for anisotropic media, Geophys. J. Int......

Xuyao Zheng

2004-12-01T23:59:59.000Z

439

Nuclear Constraints on the Weak Nucleon-Nucleon Interaction  

E-Print Network [OSTI]

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

W. C. Haxton

2008-02-21T23:59:59.000Z

440

Earth's Core Reveals an Inner Weakness | Advanced Photon Source  

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

their results to core conditions and found that the strength of iron deep within the Earth is lower than previously thought. This weakness may explain how the crystal structure...

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

Environmental Metabolomics:? A SWOT Analysis (Strengths, Weaknesses, Opportunities, and Threats)  

Science Journals Connector (OSTI)

Environmental Metabolomics:? A SWOT Analysis (Strengths, Weaknesses, Opportunities, and Threats) ... An overall goal of environmental metabolomics is to understand what is metabolomically “normal” or adaptive and what constitutes a threat to human health and the environment. ...

Marion G. Miller

2007-01-04T23:59:59.000Z

442

Weak-value amplification as an optimal metrological protocol  

E-Print Network [OSTI]

The implementation of weak-value amplification requires the pre- and post-selection of states of a quantum system, followed by the observation of the response of the meter, which interacts weakly with the system. Data acquisition from the meter is conditioned to successful post-selection events. Here we derive an optimal post-selection procedure for estimating the coupling constant between system and meter, and show that it leads both to weak-value amplification and to the saturation of the quantum Fisher information, under conditions fulfilled by all previously reported experiments on the amplification of weak signals. For most of the pre-selected states, full information on the coupling constant can be extracted from the meter data set alone, while for a small fraction of the space of pre-selected states, it must be obtained from the post-selection statistics.

G. Bié Alves; B. M. Escher; R. L. de Matos Filho; N. Zagury; L. Davidovich

2014-10-27T23:59:59.000Z

443

Strong Effect of Weak Charging in Suspensions of Anisotropic Colloids  

E-Print Network [OSTI]

Suspensions of hard colloidal particles frequently serve as model systems in studies on fundamental aspects of phase transitions. But often colloidal particles that are considered as ``hard'' are in fact weakly charged. If the colloids are spherical, weak charging has a only a weak effect on the structural properties of the suspension, which can be easily corrected for. However, this does not hold for anisotropic particles. We introduce a model for the interaction potential between charged ellipsoids of revolution (spheroids) based on the Derjaguin approximation of Debye--H\\"uckel Theory and present a computer simulation study on aspects of the system's structural properties and phase behaviour. In line with previous experimental observations, we find that even a weak surface charge has a strong impact on the correlation functions. A likewise strong impact is seen on the phase behaviour, in particular, we find stable cubatic order in suspensions of oblate ellipsoids.

Sven Dorosz; Nikhilesh Shegokar; Tanja Schilling; Martin Oettel

2014-03-21T23:59:59.000Z

444

Ultra-weak sector, Higgs boson mass, and the dilaton  

SciTech Connect (OSTI)

The Higgs boson mass may arise from a portal coupling to a singlet field $\\sigma$ which has a very large VEV $f \\gg m_\\text{Higgs}$. This requires a sector of "ultra-weak" couplings $\\zeta_i$, where $\\zeta_i \\lesssim m_\\text{Higgs}^2 / f^2$. Ultra-weak couplings are technically naturally small due to a custodial shift symmetry of $\\sigma$ in the $\\zeta_i \\rightarrow 0$ limit. The singlet field $\\sigma$ has properties similar to a pseudo-dilaton. We engineer explicit breaking of scale invariance in the ultra-weak sector via a Coleman-Weinberg potential, which requires hierarchies amongst the ultra-weak couplings.

Allison, Kyle [University of Oxford; Hill, Christopher T. [FNAL; Ross, Graham G. [University of Oxford

2014-11-01T23:59:59.000Z

445

The Hadley Circulation and the Weak Temperature Gradient Approximation  

Science Journals Connector (OSTI)

The weak temperature gradient (WTG) approximation is applied to simple shallow-water models of the Hadley circulation. While it is difficult to formally justify the use of the WTG approximation for this problem, the derived WTG solutions are ...

L. M. Polvani; A. H. Sobel

2002-05-01T23:59:59.000Z

446

Proton's Weak Charge Determined for First Time | Jefferson Lab  

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

force is one of the four fundamental forces in our universe, along with gravity, electromagnetism and the strong force. Although the weak force acts only on the sub-atomic level,...

447

A Gravitational Spreading Origin For The Socompa Debris Avalanche | Open  

Open Energy Info (EERE)

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

448

Directed search for continuous gravitational waves from the Galactic center  

E-Print Network [OSTI]

We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO’s fifth science run from two LIGO ...

Aggarwal, Nancy

449

Disc-cylinder Argonne-Maryland gravitational radiation experiments  

Science Journals Connector (OSTI)

A new kind of antenna has been developed for gravitational radiation. It consists of a disc operating in the radial mode of circular symmetry, and search has been carried out for a scalar component. The observ...

J. Weber

1971-01-11T23:59:59.000Z

450

Polarized Gravitational Waves from Gamma-Ray Bursts  

E-Print Network [OSTI]

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

Shiho Kobayashi; Peter Meszaros

2003-01-24T23:59:59.000Z

451

Tests of the Gravitational Inverse-Square Law  

E-Print Network [OSTI]

We review recent experimental tests of the gravitational inverse-square law and the wide variety of theoretical considerations that suggest the law may break down in experimentally accessible regions.

E. G. Adelberger; B. R. Heckel; A. E. Nelson

2003-07-22T23:59:59.000Z

452

Helioseismic determination of the solar gravitational quadrupole moment  

Science Journals Connector (OSTI)

......momentum and kinetic energy (top panel), and the...demonstrated that the total solar angular momentum, its total kinetic energy in rotation, and the solar gravitational quadrupole...IAC and CTIO. The MDI project operating the SOI/MDI......

Frank P. Pijpers

1998-07-01T23:59:59.000Z

453

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

454

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

455

A note on the thermodynamics of gravitational radiation  

E-Print Network [OSTI]

It is shown that linearized gravitational radiation confined in a cavity can achieve thermal equilibrium if the mean density of the radiation and the size of the cavity satisfy certain constraints.

T. Padmanabhan; T. P. Singh

2003-08-18T23:59:59.000Z

456

Phase sensitivity of slow electrons to interactions with weak potentials  

SciTech Connect (OSTI)

The interaction of very slow electrons with weak potentials is investigated in an exactly soluble, one-dimensional quantum mechanical model. Slow electrons are produced by a decelerating ramp potential, as in experimental mirror electron microscopy, so the electrons can interact with a weak field as they slow and reverse direction. Our model provides a wave mechanical interpretation of this turning point region and suggests the possibility of imaging optical fields utilizing the phase of electron matter waves.

Kennedy, S. M.; Jesson, D. E.; Morgan, M. J.; Smith, A. E.; Barker, P. F. [School of Physics, Monash University, Victoria, 3800 (Australia); Department of Physics, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH144AS (United Kingdom)

2006-10-15T23:59:59.000Z

457

Cosmic string structure at the gravitational radiation scale  

Science Journals Connector (OSTI)

We use our model of the small scale structure on cosmic strings to develop further the result of Siemens, Olum, and Vilenkin that the gravitational radiation length scale on cosmic strings is smaller than the previously assumed ?G?t. We discuss some of the properties of cosmic string loops at this cutoff scale, and we argue that recent network simulations point to two populations of cosmic string loops, one near the horizon scale and one near the gravitational radiation cutoff.

Joseph Polchinski and Jorge V. Rocha

2007-06-07T23:59:59.000Z

458

Comment on: Detecting Vanishing Dimensions Via Primordial Gravitational Wave Astronomy  

E-Print Network [OSTI]

It has been recently claimed [arXiv:1102.3434] that quantum gravity models where the number of dimensions reduces at the ultraviolet exhibit a potentially observable cutoff in the primordial gravitational wave spectrum, and that this is a "generic" and "robust" test for such models, since "(2+1)-dimensional spacetimes have no gravitational degrees of freedom". We argue that such a claim is misleading.

Thomas P. Sotiriou; Matt Visser; Silke Weinfurtner

2011-04-07T23:59:59.000Z

459

An alternative method for calculating the energy of gravitational waves  

E-Print Network [OSTI]

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

Miroslav Sukenik; Jozef Sima

1999-09-21T23:59:59.000Z

460

A perturbative and gauge invariant treatment of gravitational wave memory  

E-Print Network [OSTI]

We present a perturbative treatment of gravitational wave memory. The coordinate invariance of Einstein's equations leads to a type of gauge invariance in perturbation theory. As with any gauge invariant theory, results are more clear when expressed in terms of manifestly gauge invariant quantities. Therefore we derive all our results from the perturbed Weyl tensor rather than the perturbed metric. We derive gravitational wave memory for the Einstein equations coupled to a general energy-momentum tensor that reaches null infinity.

Lydia Bieri; David Garfinkle

2013-12-24T23:59:59.000Z

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.