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Sample records for radio weak gravitational

  1. Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Pires, Sandrine; Starck, Jean-Luc; Leonard, Adrienne; Réfrégier, Alexandre

    2012-03-01

    This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy

  2. Instrumental systematics and weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Mandelbaum, R.

    2015-05-01

    We present a pedagogical review of the weak gravitational lensing measurement process and its connection to major scientific questions such as dark matter and dark energy. Then we describe common ways of parametrizing systematic errors and understanding how they affect weak lensing measurements. Finally, we discuss several instrumental systematics and how they fit into this context, and conclude with some future perspective on how progress can be made in understanding the impact of instrumental systematics on weak lensing measurements.

  3. Baryons, neutrinos, feedback and weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Harnois-Déraps, Joachim; van Waerbeke, Ludovic; Viola, Massimo; Heymans, Catherine

    2015-06-01

    The effect of baryonic feedback on the dark matter mass distribution is generally considered to be a nuisance to weak gravitational lensing. Measurements of cosmological parameters are affected as feedback alters the cosmic shear signal on angular scales smaller than a few arcminutes. Recent progress on the numerical modelling of baryon physics has shown that this effect could be so large that, rather than being a nuisance, the effect can be constrained with current weak lensing surveys, hence providing an alternative astrophysical insight on one of the most challenging questions of galaxy formation. In order to perform our analysis, we construct an analytic fitting formula that describes the effect of the baryons on the mass power spectrum. This fitting formula is based on three scenarios of the OverWhelmingly Large hydrodynamical simulations. It is specifically calibrated for z < 1.5, where it models the simulations to an accuracy that is better than 2 per cent for scales k < 10 h Mpc-1 and better than 5 per cent for 10 < k < 100 h Mpc-1. Equipped with this precise tool, this paper presents the first constraint on baryonic feedback models using gravitational lensing data, from the Canada France Hawaii Telescope Lensing Survey (CFHTLenS). In this analysis, we show that the effect of neutrino mass on the mass power spectrum is degenerate with the baryonic feedback at small angular scales and cannot be ignored. Assuming a cosmology precision fixed by WMAP9, we find that a universe with massless neutrinos is rejected by the CFHTLenS lensing data with 85-98 per cent confidence, depending on the baryon feedback model. Some combinations of feedback and non-zero neutrino masses are also disfavoured by the data, although it is not yet possible to isolate a unique neutrino mass and feedback model. Our study shows that ongoing weak gravitational lensing surveys (KiDS, HSC and DES) will offer a unique opportunity to probe the physics of baryons at galactic scales, in

  4. Gravitational lensing in Tangherlini spacetime in the weak gravitational field and the strong gravitational field

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Naoki; Kitamura, Takao; Nakajima, Koki; Asada, Hideki

    2014-09-01

    The gravitational lensing effects in the weak gravitational field by exotic lenses have been investigated intensively to find nonluminous exotic objects. Gravitational lensing based on 1/rn fall-off metric, as a one-parameter model that can treat by hand both the Schwarzschild lens (n =1) and the Ellis wormhole (n =2) in the weak field, has been recently studied. Only for n=1 case, however, it has been explicitly shown that effects of relativistic lens images by the strong field on the light curve can be neglected. We discuss whether relativistic images by the strong field can be neglected for n>1 in the Tangherlini spacetime which is one of the simplest models for our purpose. We calculate the divergent part of the deflection angle for arbitrary n and the regular part for n=1, 2 and 4 in the strong field limit, the deflection angle for arbitrary n under the weak gravitational approximation. We also compare the radius of the Einstein ring with the radii of the relativistic Einstein rings for arbitrary n. We conclude that the images in the strong gravitational field have little effect on the total light curve and that the time-symmetric demagnification parts in the light curve will appear even after taking account of the images in the strong gravitational field for n>1.

  5. Gravitational redshift experiment on RadioAstron

    NASA Astrophysics Data System (ADS)

    Litvinov, Dmitry; Bietenholz, Michael; Rudenko, Valentin; Biriukov, Alexander; Kauts, Vladimir; Kulagin, Victor; Bartel, Norbert; Gwinn, Carl; Cannon, Wayne

    The RadioAstron space radio telescope offers a possibility for testing the gravitational redshift effect with an accuracy of better than 10(-5) , thus, improving the result of the Gravity Probe A mission by at least an order of magnitude. However, RadioAstron’s communications and frequency transfer system doesn’t allow for a direct application of the nonrelativistic Doppler and tropospheric compensation scheme used in the Gravity Probe A experiment. This results in a degradation of the redshift test accuracy to approximately 1%. We discuss two approaches to overcome this difficulty and present preliminary results based on data obtained during special observing sessions scheduled for testing the new techniques.

  6. Atomic Inference from Weak Gravitational Lensing Data

    SciTech Connect

    Marshall, Phil; /KIPAC, Menlo Park

    2005-12-14

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

  7. Separating weak lensing and intrinsic alignments using radio observations

    NASA Astrophysics Data System (ADS)

    Whittaker, Lee; Brown, Michael L.; Battye, Richard A.

    2015-07-01

    We discuss methods for performing weak lensing using radio observations to recover information about the intrinsic structural properties of the source galaxies. Radio surveys provide unique information that can benefit weak lensing studies, such as H I emission, which may be used to construct galaxy velocity maps, and polarized synchrotron radiation; both of which provide information about the unlensed galaxy and can be used to reduce galaxy shape noise and the contribution of intrinsic alignments. Using a proxy for the intrinsic position angle of an observed galaxy, we develop techniques for cleanly separating weak gravitational lensing signals from intrinsic alignment contamination in forthcoming radio surveys. Random errors on the intrinsic orientation estimates introduce biases into the shear and intrinsic alignment estimates. However, we show that these biases can be corrected for if the error distribution is accurately known. We demonstrate our methods using simulations, where we reconstruct the shear and intrinsic alignment auto- and cross-power spectra in three overlapping redshift bins. We find that the intrinsic position angle information can be used to successfully reconstruct both the lensing and intrinsic alignment power spectra with negligible residual bias.

  8. Weber's gravitational force as static weak field approximation

    NASA Astrophysics Data System (ADS)

    Tiandho, Yuant

    2016-02-01

    Weber's gravitational force (WGF) is one of gravitational model that can accommodate a non-static system because it depends not only on the distance but also on the velocity and the acceleration. Unlike Newton's law of gravitation, WGF can predict the anomalous of Mercury and gravitational bending of light near massive object very well. Then, some researchers use WGF as an alternative model of gravitation and propose a new mechanics theory namely the relational mechanics theory. However, currently we have known that the theory of general relativity which proposed by Einstein can explain gravity with very accurate. Through the static weak field approximation for the non-relativistic object, we also have known that the theory of general relativity will reduce to Newton's law of gravity. In this work, we expand the static weak field approximation that compatible with relativistic object and we obtain a force equation which correspond to WGF. Therefore, WGF is more precise than Newton's gravitational law. The static-weak gravitational field that we used is a solution of the Einstein's equation in the vacuum that satisfy the linear field approximation. The expression of WGF with ξ = 1 and satisfy the requirement of energy conservation are obtained after resolving the geodesic equation. By this result, we can conclude that WGF can be derived from the general relativity.

  9. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    SciTech Connect

    Wu Xiaoning; Huang Chaoguang; Sun Jiarui

    2008-06-15

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  10. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoning; Huang, Chao-Guang; Sun, Jia-Rui

    2008-06-01

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  11. Weak Gravitational Wave and Casimir Energy of a Scalar Field

    NASA Astrophysics Data System (ADS)

    Tavakoli, F.; Pirmoradian, R.; Parsabod, I.

    2016-09-01

    In this paper, we calculate the effect of a weak gravitational field on the Casimir force between two ideal plates subjected to a massless minimally coupled field. It is the aim of this work to study the Casimir energy under a weak perturbation of gravity. Moreover, the fluctuations of the stress-energy tensor for a scalar field in de Sitter space-time are computed as well.

  12. Coincidently Searching for Gravitational Waves and Low Frequency Radio Transients

    NASA Astrophysics Data System (ADS)

    Kavic, Michael; Yancey, C.; Shawhan, P. S.; Cutchin, S.; Simonetti, J. H.; Bear, B.; Tsai, J.

    2014-01-01

    The transient sky has become an important area of astrophysical study, especially with the appearance of recent fast transients, but little is known about the sources of these transients. One possible approach which can shed light on this area is multi-messenger astronomy using gravitational waves and prompt emission meter-wavelength radio to observe fast transients. This is made possible with gravitational-wave detectors such as LIGO, VIRGO, and GEO (IndIGO and KAGRA proposed or under construction) and phased-array radio-telescopes such LWA, LOFAR, LoFASM, and MWA. This talk presents a method for coincidence of gravitational wave and meter-wavelength radio observations to enable multi-messenger astronomy and discusses the optimization of gravitational-wave and radio sensitivities to attain effective combined observational sensitivities. It is shown that coincidence provides a 52.9% increase to the sensitivity distance for LIGO and a 200% increase to the SNR of radio arrays for particular cases.

  13. Weak gravitational shear and flexion with polar shapelets

    NASA Astrophysics Data System (ADS)

    Massey, Richard; Rowe, Barnaby; Refregier, Alexandre; Bacon, David J.; Bergé, Joel

    2007-09-01

    We derive expressions, in terms of `polar shapelets', for the image distortion operations associated with weak gravitational lensing. Shear causes galaxy shapes to become elongated, and is sensitive to the second derivative of the projected gravitational potential along their line of sight; flexion bends galaxy shapes into arcs, and is sensitive to the third derivative. Polar shapelets provide a natural representation, in which both shear and flexion transformations are compact. Through this tool, we understand progress in several weak lensing methods. We then exploit various symmetries of shapelets to construct a range of shear estimators with useful properties. Through an analogous investigation, we also explore several flexion estimators. In particular, some of the estimators can be measured simultaneously and independently for every galaxy, and will provide unique checks for systematics in future weak lensing analyses. Using simulated images from the Shear TEsting Programme, we show that we can recover input shears with no significant bias. A complete software package to parametrize astronomical images in terms of polar shapelets, and to perform a full weak lensing analysis, is available on the Internet.

  14. Tests of gravitational symmetries with radio pulsars

    NASA Astrophysics Data System (ADS)

    Shao, LiJing; Wex, Norbert

    2016-09-01

    Symmetries play important roles in modern theories of physical laws. In this paper, we review several experimental tests of important symmetries associated with the gravitational interaction, including the universality of free fall for self-gravitating bodies, time-shift symmetry in the gravitational constant, local position invariance and local Lorentz invariance of gravity, and spacetime translational symmetries. Recent experimental explorations for post-Newtonian gravity are discussed, of which, those from pulsar astronomy are highlighted. All of these tests, of very different aspects of gravity theories, at very different length scales, favor to very high precision the predictions of the strong equivalence principle (SEP) and, in particular, general relativity which embodies SEP completely. As the founding principles of gravity, these symmetries are motivated to be promoted to even stricter tests in future.

  15. The general theory of secondary weak gravitational lensing

    SciTech Connect

    Clarkson, Chris

    2015-09-01

    Weak gravitational lensing is normally assumed to have only two principle effects: a magnification of a source and a distortion of the sources shape in the form of a shear. However, further distortions are actually present owing to changes in the gravitational field across the scale of the ray bundle of light propagating to us, resulting in the familiar arcs in lensed images. This is normally called the flexion, and is approximated by Taylor expanding the shear and magnification across the image plane. However, the physical origin of this effect arises from higher-order corrections in the geodesic deviation equation governing the gravitational force between neighbouring geodesics— so involves derivatives of the Riemann tensor. We show that integrating the second-order geodesic deviation equation results in a 'Hessian map' for gravitational lensing, which is a higher-order addition to the Jacobi map. We derive the general form of the Hessian map in an arbitrary spacetime paying particular attention to the separate effects of local Ricci versus non-local Weyl curvature. We then specialise to the case of a perturbed FLRW model, and give the general form of the Hessian for the first time. This has a host of new contributions which could in principle be used as tests for modified gravity.

  16. Testing Einstein's weak equivalence principle with gravitational waves

    NASA Astrophysics Data System (ADS)

    Wu, Xue-Feng; Gao, He; Wei, Jun-Jie; Mészáros, Peter; Zhang, Bing; Dai, Zi-Gao; Zhang, Shuang-Nan; Zhu, Zong-Hong

    2016-07-01

    A conservative constraint on Einstein's weak equivalence principle (WEP) can be obtained under the assumption that the observed time delay between correlated particles from astronomical sources is dominated by the gravitational fields through which they move. Current limits on the WEP are mainly based on the observed time delays of photons with different energies. It is highly desirable to develop more accurate tests that include the gravitational wave (GW) sector. The detection by the advanced LIGO/VIRGO systems of gravitational waves will provide attractive candidates for constraining the WEP, extending the tests to gravitational interactions with potentially higher accuracy. Considering the capabilities of the advanced LIGO/VIRGO network and the source direction uncertainty, we show that the joint detection of GWs and electromagnetic signals could probe the WEP to an accuracy down to 10-10 , which is one order of magnitude tighter than previous limits, and 7 orders of magnitude tighter than the multimessenger (photons and neutrinos) results by supernova 1987A.

  17. Gravitational force in weakly correlated particle spatial distributions.

    PubMed

    Gabrielli, Andrea; Masucci, Adolfo Paolo; Labini, Francesco Sylos

    2004-03-01

    We study the statistics of the gravitational (Newtonian) force in a particular class of weakly correlated spatial distributions of pointlike and unitary mass particles generated by the so-called Gauss-Poisson point processes. In particular we extend to these distributions the analysis that Chandrasekhar introduced for purely Poisson processes. In this way we can find the explicit asymptotic behavior of the probability density function of the force for both large and small values of the field as a generalization of the Holtzmark statistics. In particular, we show how the modifications at large fields depend on the density correlations introduced at small scales. The validity of the introduced approximations is positively tested through a direct comparison with the analysis of the statistics of the gravitational force in numerical simulations of Gauss-Poisson processes.

  18. Curved Radio Spectra of Weak Cluster Shocks

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung; Ryu, Dongsu

    2015-08-01

    In order to understand certain observed features of arc-like giant radio relics such as the rareness, uniform surface brightness, and curved integrated spectra, we explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud containing fossil relativistic electrons. Toward this end, we perform DSA simulations of spherical shocks with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301, and calculate the ensuing radio synchrotron emission from re-accelerated electrons. Three types of fossil electron populations are considered: a delta-function like population with the shock injection momentum, a power-law distribution, and a power law with an exponential cutoff. The surface brightness profile of the radio-emitting postshock region and the volume-integrated radio spectrum are calculated and compared with observations. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed {u}{{s}}˜ 3× {10}3 {km} {{{s}}}-1 and sonic Mach number {M}{{s}}˜ 3. These shocks produce curved radio spectra that steepen gradually over (0.1-10){ν }{br} with a break frequency {ν }{br}˜ 1 GHz if the duration of electron acceleration is ˜60-80 Myr. However, the abrupt increase in the spectral index above ˜1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with {γ }{{e}}≳ {10}4.

  19. Curved Radio Spectra of Weak Cluster Shocks

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung; Ryu, Dongsu

    2015-08-01

    In order to understand certain observed features of arc-like giant radio relics such as the rareness, uniform surface brightness, and curved integrated spectra, we explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud containing fossil relativistic electrons. Toward this end, we perform DSA simulations of spherical shocks with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301, and calculate the ensuing radio synchrotron emission from re-accelerated electrons. Three types of fossil electron populations are considered: a delta-function like population with the shock injection momentum, a power-law distribution, and a power law with an exponential cutoff. The surface brightness profile of the radio-emitting postshock region and the volume-integrated radio spectrum are calculated and compared with observations. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed {u}{{s}}∼ 3× {10}3 {km} {{{s}}}-1 and sonic Mach number {M}{{s}}∼ 3. These shocks produce curved radio spectra that steepen gradually over (0.1–10){ν }{br} with a break frequency {ν }{br}∼ 1 GHz if the duration of electron acceleration is ∼60–80 Myr. However, the abrupt increase in the spectral index above ∼1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with {γ }{{e}}≳ {10}4.

  20. Weak Gravitational Lensing from Regular Bardeen Black Holes

    NASA Astrophysics Data System (ADS)

    Ghaffarnejad, Hossein; niad, Hassan

    2016-03-01

    In this article we study weak gravitational lensing of regular Bardeen black hole which has scalar charge g and mass m. We investigate the angular position and magnification of non-relativistic images in two cases depending on the presence or absence of photon sphere. Defining dimensionless charge parameter q= {g}/{2m} we seek to disappear photon sphere in the case of |q|>{24√5}/{125} for which the space time metric encounters strongly with naked singularities. We specify the basic parameters of lensing in terms of scalar charge by using the perturbative method and found that the parity of images is different in two cases: (a) The strongly naked singularities is present in the space time. (b) singularity of space time is weak or is eliminated (the black hole lens).

  1. Gravitational failure of sea cliffs in weakly lithified sediment

    USGS Publications Warehouse

    Hampton, M.A.

    2002-01-01

    Gravitational failure of sea cliffs eroded into weakly lithified sediment at several sites in California involves episodic stress-release fracturing and cantilevered block falls. The principal variables that influence the gravitational stability are tensional stresses generated during the release of horizontal confining stress and weakening of the sediment with increased saturation levels. Individual failures typically comprise less than a cubic meter of sediment, but large areas of a cliff face can be affected by sustained instability over a period of several days. Typically, only the outer meter or so of sediment is removed during a failure episode. In-place sediment saturation levels vary over time and space, generally being higher during the rainy season but moderate to high year-round. Laboratory direct-shear tests show that sediment cohesion decreases abruptly with increasing saturation level; the decrease is similar for all tested sediment if the cohesion is normalized by the maximum, dry-sediment cohesion. Large failures that extend over most or all of the height of the sea cliff are uncommon, but a few large wedge-shaped failures sometimes occur, as does separation of large blocks at sea cliff-gully intersections.

  2. Karhunen-Loeve Analysis for Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Vanderplas, Jacob T.

    In the past decade, weak gravitational lensing has become an important tool in the study of the universe at the largest scale, giving insights into the distribution of dark matter, the expansion of the universe, and the nature of dark energy. This thesis research explores several applications of Karhunen-Loève (KL) analysis to speed and improve the comparison of weak lensing shear catalogs to theory in order to constrain cosmological parameters in current and future lensing surveys. This work addresses three related aspects of weak lensing analysis: Three-dimensional Tomographic Mapping: (Based on work published in Vanderplas et al 2011) We explore a new fast approach to three-dimensional mass mapping in weak lensing surveys. The KL approach uses a KL-based filtering of the shear signal to reconstruct mass structures on the line-of-sight, and provides a unified framework to evaluate the efficacy of linear reconstruction techniques. We find that the KL-based filtering leads to near-optimal angular resolution, and computation times which are faster than previous approaches. We also use the KL formalism to show that linear non-parametric reconstruction methods are fundamentally limited in their ability to resolve lens redshifts. Shear Peak Statistics with Incomplete Data: (Based on work published in Vanderplas et al 2012) We explore the use of KL eigenmodes for interpolation across masked regions in observed shear maps. Mass mapping is an inherently non-local calculation, meaning gaps in the data can have a significant effect on the properties of the derived mass map. Our KL mapping procedure leads to improvements in the recovery of detailed statistics of peaks in the mass map, which holds promise of improved cosmological constraints based on such studies. Two-point parameter estimation with KL modes: The power spectrum of the observed shear can yield powerful cosmological constraints. Incomplete survey sky coverage, however, can lead to mixing of power between

  3. Searching for Correlated Radio Transients & Gravitational Wave Bursts

    NASA Astrophysics Data System (ADS)

    Kavic, Michael; Shawhan, P. S.; Yancey, C.; Cutchin, S.; Simonetti, J. H.; Bear, B.; Tsai, J.

    2013-01-01

    We will discuss an ongoing multi-messenger search for transient radio pulses and gravitational wave bursts. This work is being conducted jointly by the Long Wavelength Array (LWA) and the LIGO Scientific Collaboration (LSC). A variety of astrophysical sources can produce simultaneous emission of gravitational waves and coherent low-frequency electromagnetic radiation. The primary common source motivating this work is the merger of neutron star binaries for which the LWA and LSC instruments have comparable sensitivity. Additional common sources include supernovae, long timescale GRBs and cosmic string cusp events. Data taken by both instruments can be compared to search for correlated signals. Identification of correlated signals can be used to increase the sensitivity of both instruments. We will summarize the coincident observations which have already been conducted and outline plans for future work. We will describe the process being used for synthesizing these data set and present preliminary results.

  4. Weak Lensing by Large-Scale Structure and the Polarization Properties of Distant Radio Sources

    NASA Astrophysics Data System (ADS)

    Surpi, Gabriela C.; Harari, Diego D.

    1999-04-01

    We estimate the effects of weak lensing by large-scale density inhomogeneities and long-wavelength gravitational waves on the polarization properties of electromagnetic radiation as it propagates from cosmologically distant sources. Scalar (density) fluctuations do not rotate either the plane of polarization of the electromagnetic radiation or the source image. They do, however, produce an appreciable shear that distorts the image shape, leading to an apparent rotation of the image orientation relative to its plane of polarization. In sources with large ellipticity, the apparent rotation is rather small, of the order (in radians) of the dimensionless shear. The effect is larger at smaller source eccentricities. A shear of 1% can induce apparent rotations of around 5° in radio sources with the smallest eccentricity among those with a significant degree of integrated linear polarization. We discuss the possibility that weak lensing by shear with an rms value around or below 5% may be the cause for the dispersion in the direction of integrated linear polarization of cosmologically distant radio sources away from the perpendicular to their major axis, as expected from models of their magnetic fields. An rms shear larger than 5% would be incompatible with the observed correlation between polarization properties and source orientation in distant radio galaxies and quasars. Gravity waves do rotate both the plane of polarization and the source image. Their weak-lensing effects, however, are negligible.

  5. Combining Strong and Weak Gravitational Lensing in Abell 1689

    NASA Astrophysics Data System (ADS)

    Limousin, Marceau; Richard, Johan; Jullo, Eric; Kneib, Jean-Paul; Fort, Bernard; Soucail, Geneviève; Elíasdóttir, Árdís; Natarajan, Priyamvada; Ellis, Richard S.; Smail, Ian; Czoske, Oliver; Smith, Graham P.; Hudelot, Patrick; Bardeau, Sébastien; Ebeling, Harald; Egami, Eiichi; Knudsen, Kirsten K.

    2007-10-01

    We present a reconstruction of the mass distribution of galaxy cluster Abell 1689 at z=0.18 using detected strong lensing features from deep ACS observations and extensive ground based spectroscopy. Earlier analyses have reported up to 32 multiply imaged systems in this cluster, of which only 3 were spectroscopically confirmed. In this work, we present a parametric strong lensing mass reconstruction using 34 multiply imaged systems of which 24 have newly determined spectroscopic redshifts, which is a major step forward in building a robust mass model. In turn, the new spectroscopic data allows a more secure identification of multiply imaged systems. The resultant mass model enables us to reliably predict the redshifts of additional multiply imaged systems for which no spectra are currently available, and to use the location of these systems to further constrain the mass model. Using our strong lensing mass model, we predict on larger scale a shear signal which is consistent with that inferred from our large scale weak lensing analysis derived using CFH12K wide field images. Thanks to a new method for reliably selecting a well defined background lensed galaxy population, we resolve the discrepancy found between the NFW concentration parameters derived from earlier strong and weak lensing analysis. The derived parameters for the best fit NFW profile is found to be c200=7.6+/-1.6 and r200=2.16+/-0.10 h-170 Mpc (corresponding to a 3D mass equal to M200=[1.32+/-0.2]×1015 h70 Msolar). The large number of new constraints incorporated in this work makes Abell 1689 the most reliably reconstructed cluster to date. This well calibrated mass model, which we here make publicly available, will enable us to exploit Abell 1689 efficiently as a gravitational telescope, as well as to potentially constrain cosmology. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des

  6. TYPE III RADIO BURSTS PERTURBED BY WEAK CORONAL SHOCKS

    SciTech Connect

    Li, B.; Cairns, Iver H.

    2012-07-10

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

  7. [The use of a detector of the extremely weak radiation as a variometer of gravitation field].

    PubMed

    Gorshkov, E S; Bondarenko, E G; Shapovalov, S N; Sokolovskiĭ, V V; Troshichev, O A

    2001-01-01

    It was shown that the detector of extremely weak radiation with selectively increased sensitivity to the nonelectromagnetic, including the gravitational component of the spectrum of active physical fields can be used as the basis for constructing a variometer of gravitational field of a new type.

  8. Precise Radio-Telescope Measurements Advance Frontier Gravitational Physics

    NASA Astrophysics Data System (ADS)

    2009-09-01

    Scientists using a continent-wide array of radio telescopes have made an extremely precise measurement of the curvature of space caused by the Sun's gravity, and their technique promises a major contribution to a frontier area of basic physics. "Measuring the curvature of space caused by gravity is one of the most sensitive ways to learn how Einstein's theory of General Relativity relates to quantum physics. Uniting gravity theory with quantum theory is a major goal of 21st-Century physics, and these astronomical measurements are a key to understanding the relationship between the two," said Sergei Kopeikin of the University of Missouri. Kopeikin and his colleagues used the National Science Foundation's Very Long Baseline Array (VLBA) radio-telescope system to measure the bending of light caused by the Sun's gravity to an accuracy of 0.03 percent. With further observations, the scientists say their precision technique can make the most accurate measure ever of this phenomenon. Bending of starlight by gravity was predicted by Albert Einstein when he published his theory of General Relativity in 1916. According to relativity theory, the strong gravity of a massive object such as the Sun produces curvature in the nearby space, which alters the path of light or radio waves passing near the object. The phenomenon was first observed during a solar eclipse in 1919. Though numerous measurements of the effect have been made over the intervening 90 years, the problem of merging General Relativity and quantum theory has required ever more accurate observations. Physicists describe the space curvature and gravitational light-bending as a parameter called "gamma." Einstein's theory holds that gamma should equal exactly 1.0. "Even a value that differs by one part in a million from 1.0 would have major ramifications for the goal of uniting gravity theory and quantum theory, and thus in predicting the phenomena in high-gravity regions near black holes," Kopeikin said. To make

  9. SKA Weak Lensing I: Cosmological Forecasts and the Power of Radio-Optical Cross-Correlations

    NASA Astrophysics Data System (ADS)

    Harrison, Ian; Camera, Stefano; Zuntz, Joe; Brown, L.

    2016-09-01

    We construct forecasts for cosmological parameter constraints from weak gravitational lensing surveys involving the Square Kilometre Array (SKA). Considering matter content, dark energy and modified gravity parameters, we show that the first phase of the SKA (SKA1) can be competitive with other Stage III experiments such as the Dark Energy Survey (DES) and that the full SKA (SKA2) can potentially form tighter constraints than Stage IV optical weak lensing experiments, such as those that will be conducted with LSST, WFIRST-AFTA or Euclid-like facilities. Using weak lensing alone, going from SKA1 to SKA2 represents improvements by factors of ˜10 in matter, ˜10 in dark energy and ˜5 in modified gravity parameters. We also show, for the first time, the powerful result that comparably tight constraints (within ˜5%) for both Stage III and Stage IV experiments, can be gained from cross-correlating shear maps between the optical and radio wavebands, a process which can also eliminate a number of potential sources of systematic errors which can otherwise limit the utility of weak lensing cosmology.

  10. Gravitational lensing beyond the weak-field approximation

    NASA Astrophysics Data System (ADS)

    Perlick, Volker

    2014-01-01

    Gravitational lensing is considered in the full spacetime formalism of general relativity, assuming that the light rays are lightlike geodesics in a Lorentzian manifold. The review consists of three parts. The first part is devoted to spherically symmetric and static spacetimes. In particular, an exact lens map for this situation is discussed. The second part is on axisymmetric and stationary spacetimes. It concentrates on the investigation of the photon region, i.e., the region filled by spherical lightlike geodesics, in the Kerr spacetime. The photon region is of crucial relevance for the formation of a shadow. Finally, the third part briefly addresses two topics that apply to spacetimes without symmetry, namely Fermat's principle and the exact lens map of Frittelli and Newman.

  11. Gravitational lensing beyond the weak-field approximation

    SciTech Connect

    Perlick, Volker

    2014-01-14

    Gravitational lensing is considered in the full spacetime formalism of general relativity, assuming that the light rays are lightlike geodesics in a Lorentzian manifold. The review consists of three parts. The first part is devoted to spherically symmetric and static spacetimes. In particular, an exact lens map for this situation is discussed. The second part is on axisymmetric and stationary spacetimes. It concentrates on the investigation of the photon region, i.e., the region filled by spherical lightlike geodesics, in the Kerr spacetime. The photon region is of crucial relevance for the formation of a shadow. Finally, the third part briefly addresses two topics that apply to spacetimes without symmetry, namely Fermat’s principle and the exact lens map of Frittelli and Newman.

  12. Deep HST imaging of distant weak radio and field galaxies

    NASA Technical Reports Server (NTRS)

    Windhorst, R. A.; Gordon, J. M.; Pascarelle, S. M.; Schmidtke, P. C.; Keel, W. C.; Burkey, J. M.; Dunlop, J. S.

    1994-01-01

    We present deep Hubble Space Telescope (HST) Wide-Field Camera (WFC) V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring Full Width at Half Maximum (FWHM) of less than or equal to 0.2 sec, (nearly) preserve photons and signal-to-noise ratio at low spatial frequencies, and produce consistent light profiles down to our 2 sigma surface brightness sensitivity limit of V approximately 27.2 and I approximately 25.9 mag/sq arcsec. Multi-component image modeling was used to provide deconvolution-independent estimates of structural parameters for symmetric galaxies. We present 12-band (m(sub 2750) UBVRIgriJHK) photometry for a subset of the galaxies and bootstrap the unknown FOC/48 zero point at 2750 A in three independent ways (yielding m(sub 2750) = 21.34 +/- 0.09 mag for 1.0 e(-)/s). Two radio galaxies with z = 0.311 and 0.528, as well as one field galaxy with z = 0.58, have the colors and spectra of early-type galaxies, and a(exp 1/4)-like light profiles in the HST images. The two at z greater than 0.5 have little or no color gradients in V - I and are likely giant ellipticals, while the z = 0.311 radio galaxy has a dim exponential disk and is likely an S0. Six of the seven field galaxies have light profiles that indicate (small) inner bulges following a(exp 1/4) laws and outer exponential disks, both with little or no color gradients. These are (early-type) spiral galaxies with z = 0.131-0.528. About half have faint companions or bars. One shows lumpy structure, possibly a merger. The compact narrow-line galaxy 53W002 at z = 2.390 has less than or = 30% +/- 10% of its HST V and I flux in the central kiloparsec (due to its weak Active Galactic Nucleus (AGN)). Most of its light (V approximately equal to 23.3) occurs in a symmetric envelope with a regular a(exp 1/4)-like profile of effective

  13. Constraining modified gravitational theories by weak lensing with Euclid

    SciTech Connect

    Martinelli, Matteo; Calabrese, Erminia; De Bernardis, Francesco; Melchiorri, Alessandro; Pagano, Luca; Scaramella, Roberto

    2011-01-15

    Future proposed satellite missions such as Euclid can offer the opportunity to test general relativity on cosmic scales through mapping of the galaxy weak-lensing signal. In this paper we forecast the ability of these experiments to constrain modified gravity scenarios such as those predicted by scalar-tensor and f(R) theories. We find that Euclid will improve constraints expected from the Planck satellite on these modified theories of gravity by 2 orders of magnitude. We discuss parameter degeneracies and the possible biases introduced by modifications to gravity.

  14. Radio Follow-up of Gravitational-wave Triggers during Advanced LIGO O1

    NASA Astrophysics Data System (ADS)

    Palliyaguru, N. T.; Corsi, A.; Kasliwal, M. M.; Cenko, S. B.; Frail, D. A.; Perley, D. A.; Mishra, N.; Singer, L. P.; Gal-Yam, A.; Nugent, P. E.; Surace, J. A.

    2016-10-01

    We present radio follow-up observations carried out with the Karl G. Jansky Very Large Array during the first observing run (O1) of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). A total of three gravitational-wave triggers were followed-up during the ≈ 4 months of O1, from 2015 September to 2016 January. Two of these triggers, GW150914 and GW151226, are binary black hole (BH) merger events of high significance. A third trigger, G194575, was subsequently declared as an event of no interest (i.e., a false alarm). Our observations targeted selected optical transients identified by the intermediate Palomar Transient Factory in the Advanced LIGO error regions of the three triggers, and a limited region of the gravitational-wave localization area of G194575 not accessible to optical telescopes due to Sun constraints, where a possible high-energy transient was identified. No plausible radio counterparts to GW150914 and GW151226 were found, in agreement with expectations for binary BH mergers. We show that combining optical and radio observations is key to identifying contaminating radio sources that may be found in the follow-up of gravitational-wave triggers, such as emission associated with star formation and active galactic nuclei. We discuss our results in the context of the theoretical predictions for radio counterparts to gravitational-wave transients, and describe our future plans for the radio follow-up of Advanced LIGO (and Virgo) triggers.

  15. A Coincident Search for Radio and Gravitational Waves from Binary Neutron Star Mergers

    NASA Astrophysics Data System (ADS)

    Cardena, Brett

    2011-05-01

    The merger of neutron star-neutron star binary pairs may be accompanied by the prompt emission of a coherent low-frequency radio pulse. This radio transient is produced as synchrotron radiation caused by the spin and rotation of the surface charge density of a pulsar through the magnetosphere of a larger neutron star, usually referred to as a Magnetar . This type of merger event would also result in the release of a gravitational coalescence wave-form. We will discuss a coincident radio transient and gravitational wave search. This search is being conducted by two radio telescope arrays: The Long Wave Array (LWA) and the Eight-meter-wavelength Transient Array (ETA) in coordination with the Laser Interferometer Gravitational-Wave Observatory (LIGO). We will outline this ongoing coincident search and discuss some preliminary results.

  16. Search for and study of weak radio galaxies with large angular sizes using the NVSS data

    NASA Astrophysics Data System (ADS)

    Solovyov, D. I.; Verkhodanov, O. V.

    2014-08-01

    A new method for distinguishing candidate giant radio galaxies is proposed and applied. The method is based on comparing the axes of the extended components of NVSS radio sources with separations exceeding 4', described in a catalog of presumably independent objects. Objects detected using the proposed algorithm include 16 new weak giant-radio-galaxy candidates, for which optical and radio identifications have been obtained using the CATS, NED, SDSS, and SkyView databases.

  17. RADIO OBSERVATIONS OF WEAK ENERGY RELEASES IN THE SOLAR CORONA

    SciTech Connect

    Ramesh, R.; Kathiravan, C.; Barve, Indrajit V.; Beeharry, G. K.; Rajasekara, G. N.

    2010-08-10

    We report observations of weak, circularly polarized, structureless type III bursts from the solar corona in the absence of H{alpha}/X-ray flares and other related activity, during the minimum between the sunspot cycles 23 and 24. The spectral information about the event obtained with the CALLISTO spectrograph at Mauritius revealed that the drift rate of the burst is {approx}-30 MHz s{sup -1} is in the range 50-120 MHz. Two-dimensional imaging observations of the burst at 77 MHz obtained with the Gauribidanur radioheliograph indicate that the emission region was located at a radial distance of {approx}1.5 R{sub sun} in the solar atmosphere. The estimated peak brightness temperature of the burst at 77 MHz is {approx}10{sup 8} K. We derived the average magnetic field at the aforementioned location of the burst using the one-dimensional (east-west) Gauribidanur radio polarimeter at 77 MHz, and the value is {approx}2.5 {+-} 0.2 G. We also estimated the total energy of the non-thermal electrons responsible for the observed burst as {approx}1.1 x 10{sup 24} erg. This is low compared to the energy of the weakest hard X-ray microflares reported in the literature, which is about {approx}10{sup 26} erg. The present result shows that non-thermal energy releases that correspond to the nanoflare category (energy {approx}10{sup 24} erg) are taking place in the solar corona, and the nature of such small-scale energy releases has not yet been explored.

  18. Commensal searches for microhertz gravitational waves and fast radio bursts: A pilot study

    NASA Astrophysics Data System (ADS)

    Shannon, Ryan; Hobbs, George; Ravi, Vikram

    2014-04-01

    In this pilot observing programme, we propose to observe at high cadence the transient gravitational-wave and radio-wave Universe. The goals of these observations are threefold: 1) To improve the timing precision of secondary pulsars in the Parkes Pulsar Timing Array (PPTA) to accelerate the detection of gravitational waves; 2) To characterise the gravitational wave universe in the hitherto unexplored microhertz frequency band; and 3) To develop methods and search for fast radio bursts (FRBs) while conducting precision time experiments. To achieve these goals, we request 120 hours of observations with the Parkes multibeam system, divided into 10 epochs comprising 12-hour LST days. This pilot project acts as a feasibility study for modifications to both the PPTA project and the International Pulsar Timing Array (IPTA), the consortium coordinating timing array observations in Australia, Europe, and North America, and assess the feasibility of searching for fast radio bursts while conduction precision timing observations.

  19. Weak Gravitational Lensing by Galaxy Troughs in the Dark Energy Survey

    NASA Astrophysics Data System (ADS)

    Gruen, Daniel; Dark Energy Survey Collaboration

    2016-06-01

    The Dark Energy Survey (DES) is in the process of imaging 5000 sq. deg. of the southern sky in five broad-band filters. Its primary purpose is to constrain cosmology and the physics of dark energy using weak gravitational lensing, galaxy clusters, baryonic acoustic oscillations, and supernova distance measurements.I will give an overview of weak gravitational lensing results from early DES data, with a focus on the newly developed galaxy trough statistics. Using the latter, we have made the highest signal-to-noise lensing measurements of the low density Universe to date, probing gravity and structure formation in the underdense regime. Besides these recent results, I will give an outlook on cosmological and astrophysical applications of the trough lensing signal.

  20. Localized electromagnetic and weak gravitational fields in the source-free space.

    PubMed

    Borzdov, G N

    2001-03-01

    Localized electromagnetic and weak gravitational time-harmonic fields in the source-free space are treated using expansions in plane waves. The presented solutions describe fields having a very small (about several wavelengths) and clearly defined core region with maximum intensity of field oscillations. In a given Lorentz frame L, a set of the obtained exact time-harmonic solutions of the free-space homogeneous Maxwell equations consists of three subsets (storms, whirls, and tornados), for which time average energy flux is identically zero at all points, azimuthal and spiral, respectively. In any other Lorentz frame L', they will be observed as a kind of electromagnetic missile moving without dispersing at speed Vweak gravitational fields with similar properties are also presented. The properties of these fields are illustrated in graphic form. PMID:11308787

  1. Constraining stochastic gravitational wave background from weak lensing of CMB B-modes

    NASA Astrophysics Data System (ADS)

    Shaikh, Shabbir; Mukherjee, Suvodip; Rotti, Aditya; Souradeep, Tarun

    2016-09-01

    A stochastic gravitational wave background (SGWB) will affect the CMB anisotropies via weak lensing. Unlike weak lensing due to large scale structure which only deflects photon trajectories, a SGWB has an additional effect of rotating the polarization vector along the trajectory. We study the relative importance of these two effects, deflection & rotation, specifically in the context of E-mode to B-mode power transfer caused by weak lensing due to SGWB. Using weak lensing distortion of the CMB as a probe, we derive constraints on the spectral energy density (ΩGW) of the SGWB, sourced at different redshifts, without assuming any particular model for its origin. We present these bounds on ΩGW for different power-law models characterizing the SGWB, indicating the threshold above which observable imprints of SGWB must be present in CMB.

  2. Initial Results from a Laboratory Emulation of Weak Gravitational Lensing Measurements

    NASA Astrophysics Data System (ADS)

    Seshadri, S.; Shapiro, C.; Goodsall, T.; Fucik, J.; Hirata, C.; Rhodes, J. D.; Rowe, B. T. P.; Smith, R. M.

    2013-09-01

    Weak gravitational lensing observations are a key science driver for the NASA Wide Field Infrared Survey Telescope (WFIRST). To validate the performance of the WFIRST infrared detectors, we have performed a laboratory emulation of weak gravitational lensing measurements. Our experiments used a custom precision projector system to image a target mask composed of a grid of pinholes, emulating stellar point sources, onto a 1.7 μm cut-off Teledyne HgCdTe/H2RG detector. We used a 0.88 μm LED illumination source and f/22 pupil stop to produce undersampled point spread functions similar to those expected from WFIRST. We also emulated the WFIRST image reconstruction strategy, using the image combination (IMCOM) algorithm to derive oversampled images from dithered, undersampled input images. We created shear maps for this data and computed shear correlation functions to mimic a real weak lensing analysis. After removing only second-order polynomial fits to the shear maps, we found that the correlation functions could be reduced to O(10-6). This places a conservative upper limit on the detector-induced bias to the correlation function (under our test conditions). This bias is two orders of magnitude lower than the expected weak lensing signal. Restricted to scales relevant to dark energy analyses (sky separations >0.5'), the bias is O(10-7)—comparable to the requirement for future weak lensing missions to avoid biasing cosmological parameter estimates. Our experiment will need to be upgraded and repeated under different configurations to fully characterize the shape measurement performance of WFIRST IR detectors.

  3. Gravitational-wave Constraints on the Progenitors of Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Callister, Thomas; Kanner, Jonah; Weinstein, Alan

    2016-07-01

    The nature of fast radio bursts (FRBs) remains enigmatic. Highly energetic radio pulses of millisecond duration, FRBs are observed with dispersion measures consistent with an extragalactic source. A variety of models have been proposed to explain their origin. One popular class of theorized FRB progenitor is the coalescence of compact binaries composed of neutron stars and/or black holes. Such coalescence events are strong gravitational-wave emitters. We demonstrate that measurements made by the LIGO and Virgo gravitational-wave observatories can be leveraged to severely constrain the validity of FRB binary coalescence models. Existing measurements constrain the binary black hole rate to approximately 5% of the FRB rate, and results from Advanced LIGO’s O1 and O2 observing runs may place similarly strong constraints on the fraction of FRBs due to binary neutron star and neutron star-black hole progenitors.

  4. Constraining the neutrino emission of gravitationally lensed Flat-Spectrum Radio Quasars with ANTARES data

    SciTech Connect

    Adrián-Martínez, S.; Ardid, M.; Bou-Cabo, M.; André, M.; Anton, G.; Aubert, J.-J.; Bertin, V.; Brunner, J.; Busto, J.; Basa, S.; Biagi, S.; Capone, A.; Caramete, L.; and others

    2014-11-01

    This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazar populations. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed Flat-Spectrum Radio Quasars. The magnification factor is estimated for each system assuming a singular isothermal profile for the lens. Based on data collected from 2007 to 2012 by the ANTARES neutrino telescope, the strongest constraint is obtained from the lensed quasar B0218+357, providing a limit on the total neutrino luminosity of this source of 1.08× 10{sup 46} erg s{sup -1}. This limit is about one order of magnitude lower than those previously obtained in the ANTARES standard point source searches with non-lensed Flat-Spectrum Radio Quasars.

  5. Strategies for Finding Prompt Radio Counterparts to Gravitational Wave Transients with the Murchison Widefield Array

    NASA Astrophysics Data System (ADS)

    Kaplan, D. L.; Murphy, T.; Rowlinson, A.; Croft, S. D.; Wayth, R. B.; Trott, C. M.

    2016-10-01

    Wepresent and evaluate several strategies to search for prompt, low-frequency radio emission associated with gravitational wave transients using the Murchison Widefield Array. As we are able to repoint the Murchison Widefield Array on timescales of tens of seconds, we can search for the dispersed radio signal that has been predicted to originate along with or shortly after a neutron star-neutron star merger. We find that given the large, 600 deg2 instantaneous field of view of the Murchison Widefield Array, we can cover a significant fraction of the predicted gravitational wave error region, although due to the complicated geometry of the latter, we only cover > 50% of the error region for approximately 5% of events, and roughly 15% of events will be located < 10° from the Murchison Widefield Array pointing centre such that they will be covered in the radio images. For optimal conditions, our limiting flux density for a 10-s long transient would be 0.1 Jy, increasing to about 1 Jy for a wider range of events. This corresponds to luminosity limits of 1038-39 erg s-1 based on expectations for the distances of the gravitational wave transients, which should be sufficient to detect or significantly constrain a range of models for prompt emission.

  6. Detectable radio flares following gravitational waves from mergers of binary neutron stars.

    PubMed

    Nakar, Ehud; Piran, Tsvi

    2011-09-28

    Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled.

  7. Higgs gravitational interaction, weak boson scattering, and Higgs inflation in Jordan and Einstein frames

    SciTech Connect

    Ren, Jing; Xianyu, Zhong-Zhi; He, Hong-Jian E-mail: xianyuzhongzhi@gmail.com

    2014-06-01

    We study gravitational interaction of Higgs boson through the unique dimension-4 operator ξH{sup †}HR, with H  the Higgs doublet and R  the Ricci scalar curvature. We analyze the effect of this dimensionless nonminimal coupling ξ  on weak gauge boson scattering in both Jordan and Einstein frames. We explicitly establish the longitudinal-Goldstone equivalence theorem with nonzero ξ coupling in both frames, and analyze the unitarity constraints. We study the ξ-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 (14 TeV) and the next generation pp colliders (50-100 TeV). 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.

  8. Weyl fluid dark matter model tested on the galactic scale by weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Wong, K. C.; Harko, T.; Cheng, K. S.; Gergely, L. Á.

    2012-08-01

    The higher-dimensional Weyl curvature induces on the brane a new source of gravity. This Weyl fluid of geometrical origin (reducing in the spherically symmetric, static configuration to a dark radiation and dark pressure) modifies spacetime geometry around galaxies and has been shown to explain the flatness of galactic rotation curves. Independent observations for discerning between the Weyl fluid and other dark matter models are necessary. Gravitational lensing could provide such a test. Therefore we study null geodesics and weak gravitational lensing in the dark radiation dominated region of galaxies in a class of spherically symmetric braneworld metrics. We find that the lensing profile in the braneworld scenario is distinguishable from dark matter lensing, despite both the braneworld scenario and dark matter models fitting the rotation curve data. In particular, in the asymptotic regions, light deflection is 18% enhanced as compared to dark matter halo predictions. For a linear equation of state of the Weyl fluid, we further find a critical radius below which braneworld effects reduce, while above it they amplify light deflection. This is in contrast to any dark matter model, the addition of which always increases the deflection angle.

  9. Rotation of the cosmic microwave background polarization from weak gravitational lensing.

    PubMed

    Dai, Liang

    2014-01-31

    When a cosmic microwave background (CMB) photon travels from the surface of last scatter through spacetime metric perturbations, the polarization vector may rotate about its direction of propagation. This gravitational rotation is distinct from, and occurs in addition to, the lensing deflection of the photon trajectory. This rotation can be sourced by linear vector or tensor metric perturbations and is fully coherent with the curl deflection field. Therefore, lensing corrections to the CMB polarization power spectra as well as the temperature-polarization cross correlations due to nonscalar perturbations are modified. The rotation does not affect lensing by linear scalar perturbations, but needs to be included when calculations go to higher orders. We present complete results for weak lensing of the full-sky CMB power spectra by general linear metric perturbations, taking into account both deflection of the photon trajectory and rotation of the polarization. For the case of lensing by gravitational waves, we show that the B modes induced by the rotation largely cancel those induced by the curl component of deflection. PMID:24580435

  10. An accurate and practical method for inference of weak gravitational lensing from galaxy images

    NASA Astrophysics Data System (ADS)

    Bernstein, Gary M.; Armstrong, Robert; Krawiec, Christina; March, Marisa C.

    2016-07-01

    We demonstrate highly accurate recovery of weak gravitational lensing shear using an implementation of the Bayesian Fourier Domain (BFD) method proposed by Bernstein & Armstrong, extended to correct for selection biases. The BFD formalism is rigorously correct for Nyquist-sampled, background-limited, uncrowded images of background galaxies. BFD does not assign shapes to galaxies, instead compressing the pixel data D into a vector of moments M, such that we have an analytic expression for the probability P(M|g) of obtaining the observations with gravitational lensing distortion g along the line of sight. We implement an algorithm for conducting BFD's integrations over the population of unlensed source galaxies which measures ≈10 galaxies s-1 core-1 with good scaling properties. Initial tests of this code on ≈109 simulated lensed galaxy images recover the simulated shear to a fractional accuracy of m = (2.1 ± 0.4) × 10-3, substantially more accurate than has been demonstrated previously for any generally applicable method. Deep sky exposures generate a sufficiently accurate approximation to the noiseless, unlensed galaxy population distribution assumed as input to BFD. Potential extensions of the method include simultaneous measurement of magnification and shear; multiple-exposure, multiband observations; and joint inference of photometric redshifts and lensing tomography.

  11. Analogy between general relativity and electromagnetism for slowly moving particles in weak gravitational fields

    NASA Astrophysics Data System (ADS)

    Harris, Edward G.

    1991-05-01

    Starting from the equations of general relativity, equations similar to those of electromagnetic theory are derived. It is assumed that the particles are slowly moving (v≪c), and the gravitational field is sufficiently weak that nonlinear terms in Einstein's field equations can be neglected. For static fields, the analogy to electrostatics and magnetostatics is very close. Results are compared with those of a previous derivation by Braginsky, Caves, and Thorne [Phys. Rev. D 15, 2047-2068 (1977)]. These results lead to very simple derivations of the Lense-Thirring precession [Phys. Z. 19, 156-163 (1918)] and the spin-curvature force of Papepetrou [Proc. R. Soc. London Ser. A 209, 248-258 (1951)] and Pirani [Acta Phys. Pol. 15, 389-405 (1956)].

  12. Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013

    NASA Astrophysics Data System (ADS)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, K. N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Pereira, R.; Perreca, A.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stiles, D.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Archibald, A. M.; Banaszak, S.; Berndsen, A.; Boyles, J.; Cardoso, R. F.; Chawla, P.; Cherry, A.; Dartez, L. P.; Day, D.; Epstein, C. R.; Ford, A. J.; Flanigan, J.; Garcia, A.; Hessels, J. W. T.; Hinojosa, J.; Jenet, F. A.; Karako-Argaman, C.; Kaspi, V. M.; Keane, E. F.; Kondratiev, V. I.; Kramer, M.; Leake, S.; Lorimer, D.; Lunsford, G.; Lynch, R. S.; Martinez, J. G.; Mata, A.; McLaughlin, M. A.; McPhee, C. A.; Penucci, T.; Ransom, S.; Roberts, M. S. E.; Rohr, M. D. W.; Stairs, I. H.; Stovall, K.; van Leeuwen, J.; Walker, A. N.; Wells, B. L.; LIGO Scientific Collaboration; Virgo Collaboration

    2016-06-01

    We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.

  13. THE ABUNDANCE OF X-SHAPED RADIO SOURCES: IMPLICATIONS FOR THE GRAVITATIONAL WAVE BACKGROUND

    SciTech Connect

    Roberts, David H.; Saripalli, Lakshmi; Subrahmanyan, Ravi

    2015-09-01

    Coalescence of supermassive black holes (SMBHs) in galaxy mergers is potentially the dominant contributor to the low frequency gravitational wave background (GWB). It was proposed by Merritt and Ekers that X-shaped radio galaxies are signposts of such coalescences and that their abundance might be used to predict the magnitude of the GWB. In Roberts et al. we presented radio images of all 52 X-shaped radio source candidates out of the sample of 100 selected by Cheung for which archival VLA data were available. These images indicate that at most 21% of the candidates might be genuine X-shaped radio sources that were formed by a restarting of beams in a new direction following a major merger. This suggests that fewer than 1.3% of extended radio sources appear to be candidates for genuine axis reorientations (“spin flips”), much smaller than the 7% suggested by Leahy and Parma. Thus, the associated GWB may be substantially smaller than previous estimates. These results can be used to normalize detailed calculations of the SMBH coalescence rate and the GWB.

  14. Constraining Horava-Lifshitz gravity by weak and strong gravitational lensing

    SciTech Connect

    Horvath, Zsolt; Gergely, Laszlo A.; Keresztes, Zoltan; Harko, Tiberiu; Lobo, Francisco S. N.

    2011-10-15

    We discuss gravitational lensing in the Kehagias-Sfetsos space-time emerging in the framework of Horava-Lifshitz gravity. In weak lensing, we show that there are three regimes, depending on the value of {lambda}=1/{omega}d{sup 2}, where {omega} is the Horava-Lifshitz parameter and d characterizes the lensing geometry. When {lambda} is close to zero, light deflection typically produces two images, as in Schwarzschild lensing. For very large {lambda}, the space-time approaches flatness, therefore there is only one undeflected image. In the intermediate range of {lambda}, only the upper focused image is produced due to the existence of a maximal deflection angle {delta}{sub max}, a feature inexistent in the Schwarzschild weak lensing. We also discuss the location of Einstein rings, and determine the range of the Horava-Lifshitz parameter compatible with present-day lensing observations. Finally, we analyze in the strong lensing regime the first two relativistic Einstein rings and determine the constraints on the parameter range to be imposed by forthcoming experiments.

  15. WEAK GRAVITATIONAL LENSING AS A PROBE OF PHYSICAL PROPERTIES OF SUBSTRUCTURES IN DARK MATTER HALOS

    SciTech Connect

    Shirasaki, Masato

    2015-02-01

    We propose a novel method to select satellite galaxies in outer regions of galaxy groups or clusters using weak gravitational lensing. The method is based on the theoretical expectation that the tangential shear pattern around satellite galaxies would appear with negative values at an offset distance from the center of the main halo. We can thus locate the satellite galaxies statistically with an offset distance of several lensing smoothing scales by using the standard reconstruction of surface mass density maps from weak lensing observation. We test the idea using high-resolution cosmological simulations. We show that subhalos separated from the center of the host halo are successfully located even without assuming the position of the center. For a number of such subhalos, the characteristic mass and offset length can be also estimated on a statistical basis. We perform a Fisher analysis to show how well upcoming weak lensing surveys can constrain the mass density profile of satellite galaxies. In the case of the Large Synoptic Survey Telescope with a sky coverage of 20,000 deg{sup 2}, the mass of the member galaxies in the outer region of galaxy clusters can be constrained with an accuracy of ∼0.1 dex for galaxy clusters with mass 10{sup 14} h {sup –1} M {sub ☉} at z = 0.15. Finally we explore the detectability of tidal stripping features for subhalos having a wide range of masses of 10{sup 11}-10{sup 13} h {sup –1} M {sub ☉}.

  16. Simulations of weak gravitational lensing - II. Including finite support effects in cosmic shear covariance matrices

    NASA Astrophysics Data System (ADS)

    Harnois-Déraps, Joachim; van Waerbeke, Ludovic

    2015-07-01

    Numerical N-body simulations play a central role in the assessment of weak gravitational lensing statistics, residual systematics and error analysis. In this paper, we investigate and quantify the impact of finite simulation volume on weak lensing two- and four-point statistics. These finite support (FS) effects are modelled for several estimators, simulation box sizes and source redshifts, and validated against a new large suite of 500 N-body simulations. The comparison reveals that our theoretical model is accurate to better than 5 per cent for the shear correlation function ξ+(θ) and its error. We find that the most important quantities for FS modelling are the ratio between the measured angle θ and the angular size of the simulation box at the source redshift, θbox(zs), or the multipole equivalent ℓ/ℓbox(zs). When this ratio reaches 0.1, independently of the source redshift, the shear correlation function ξ+ is suppressed by 5, 10, 20 and 25 per cent for Lbox = 1000, 500, 250 and 147 h-1 Mpc, respectively. The same effect is observed in ξ-(θ), but at much larger angles. This has important consequences for cosmological analyses using N-body simulations and should not be overlooked. We propose simple semi-analytic correction strategies that account for shape noise and survey masks, generalizable to any weak lensing estimator. From the same simulation suite, we revisit the existing non-Gaussian covariance matrix calibration of the shear correlation function, and propose a new one based on the 9-year Wilkinson Microwave Anisotropy Probe)+baryon acoustic oscillations+supernova cosmology. Our calibration matrix is accurate at 20 per cent down to the arcminute scale, for source redshifts in the range 0 < z < 3, even for the far off-diagonal elements. We propose, for the first time, a parametrization for the full ξ- covariance matrix, also 20 per cent accurate for most elements.

  17. Solar gravitational deflection of radio waves measured by very-long-baseline interferometry

    NASA Technical Reports Server (NTRS)

    Counselman, C. C., III; Kent, S. M.; Knight, C. A.; Shapiro, I. I.; Clark, T. A.; Hinteregger, H. F.; Rogers, A. E. E.; Whitney, A. R.

    1974-01-01

    Utilizing a four-antenna technique, simultaneous observations were made, at each end of an 845-km baseline, of the radio sources 3C279 and 3C273B, which are 10 deg apart in the sky. Differences in interferometric phases at 3.7-cm wavelength monitored near the time of the 1972 occultation of 3C279 by the sun, yielded a gravitational deflection of 0.99 plus or minus 0.03 times the value predicted by general relativity, corresponding to gamma = 0.98 plus or minus 0.06 (standard error).

  18. Radio Weak Lensing Shear Measurement in the Visibility Domain - I. Methodology

    NASA Astrophysics Data System (ADS)

    Rivi, M.; Miller, L.; Makhathini, S.; Abdalla, F. B.

    2016-08-01

    The high sensitivity of the new generation of radio telescopes such as the Square Kilometre Array (SKA) will allow cosmological weak lensing measurements at radio wavelengths that are competitive with optical surveys. We present an adaptation to radio data of lensfit, a method for galaxy shape measurement originally developed and used for optical weak lensing surveys. This likelihood method uses an analytical galaxy model and makes a Bayesian marginalisation of the likelihood over uninteresting parameters. It has the feature of working directly in the visibility domain, which is the natural approach to adopt with radio interferometer data, avoiding systematics introduced by the imaging process. As a proof of concept, we provide results for visibility simulations of individual galaxies with flux density S ≥ 10μJy at the phase centre of the proposed SKA1-MID baseline configuration, adopting 12 frequency channels in the band 950 - 1190 MHz. Weak lensing shear measurements from a population of galaxies with realistic flux and scalelength distributions are obtained after natural gridding of the raw visibilities. Shear measurements are expected to be affected by `noise bias': we estimate the bias in the method as a function of signal-to-noise ratio (SNR). We obtain additive and multiplicative bias values that are comparable to SKA1 requirements for SNR > 18 and SNR > 30, respectively. The multiplicative bias for SNR >10 is comparable to that found in ground-based optical surveys such as CFHTLenS, and we anticipate that similar shear measurement calibration strategies to those used for optical surveys may be used to good effect in the analysis of SKA radio interferometer data.

  19. A New Class of Weak Radio Bursts: Nanoflares and Coronal Heating?

    NASA Astrophysics Data System (ADS)

    Lonsdale, C.; Oberoi, D.; S, A.; Timar, B.; Pankratius, V.

    2014-12-01

    The newly commissioned Murchison Widefield Array (MWA) has revealed the presence of a numerous weak and short lived low frequency radio solar bursts. These emission features have duration of order a second, have relatively narrow spectral widths and are surprisingly numerous even during quiet solar conditions. Their appearance in the time-frequency plane is unlike that of the any of the known classes of radio bursts, and they at least an order of magnitude weaker than the weakest type III bursts routinely monitored and reported (e.g. by Automated Radio Burst Identification System operational at the Learmonth Radioheliograph in Australia). For the few bursts which have been studied in detail, we have not found a counterpart at X-Ray or EUV bands. There is an exciting possibility that these bursts are associated with the widely hypothesized "nanoflares" thought to play a role in coronal heating through magnetic reconnection on small scales in coronal loops. A systematic and detailed characterization of the statistical properties of these bursts over large temporal and spectral spans is necessary for investigating the role these bursts might play in coronal heating. To enable this, we have developed a novel system using region-growing, wavelet decompositions, and thresholding techniques for event recognition and parameter extraction in an automated manner for the voluminous MWA interferometric data. We will present and describe the statistical properties of these weak radio bursts based on a large number of events detected and parameterized by these automated methods.

  20. Probing Dark Energy via Weak Gravitational Lensing with the Supernova Acceleration Probe (SNAP)

    SciTech Connect

    Albert, J.; Aldering, G.; Allam, S.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Aumeunier, M.; Bailey, S.; Baltay, C.; Barrelet, E.; Basa, S.; Bebek, C.; Bergstom, L.; Bernstein, G.; Bester, M.; Besuner, B.; Bigelow, B.; Blandford, R.; Bohlin, R.; Bonissent, A.; /Caltech /LBL, Berkeley /Fermilab /SLAC /Stockholm U. /Paris, IN2P3 /Marseille, CPPM /Marseille, Lab. Astrophys. /Yale U. /Pennsylvania U. /UC, Berkeley /Michigan U. /Baltimore, Space Telescope Sci. /Indiana U. /Caltech, JPL /Australian Natl. U., Canberra /American Astron. Society /Chicago U. /Cambridge U. /Saclay /Lyon, IPN

    2005-08-08

    SNAP is a candidate for the Joint Dark Energy Mission (JDEM) that seeks to place constraints on the dark energy using two distinct methods. The first, Type Ia SN, is discussed in a separate white paper. The second method is weak gravitational lensing, which relies on the coherent distortions in the shapes of background galaxies by foreground mass structures. The excellent spatial resolution and photometric accuracy afforded by a 2-meter space-based observatory are crucial for achieving the high surface density of resolved galaxies, the tight control of systematic errors in the telescope's Point Spread Function (PSF), and the exquisite redshift accuracy and depth required by this project. These are achieved by the elimination of atmospheric distortion and much of the thermal and gravity loads on the telescope. The SN and WL methods for probing dark energy are highly complementary and the error contours from the two methods are largely orthogonal. The nominal SNAP weak lensing survey covers 1000 square degrees per year of operation in six optical and three near infrared filters (NIR) spanning the range 350 nm to 1.7 {micro}m. This survey will reach a depth of 26.6 AB magnitude in each of the nine filters and allow for approximately 100 resolved galaxies per square arcminute, {approx} 3 times that available from the best ground-based surveys. Photometric redshifts will be measured with statistical accuracy that enables scientific applications for even the faint, high redshift end of the sample. Ongoing work aims to meet the requirements on systematics in galaxy shape measurement, photometric redshift biases, and theoretical predictions.

  1. A radio survey of weak T Tauri stars in Taurus-Auriga

    SciTech Connect

    O'neal, D.; Feigelson, E.D.; Mathieu, R.D.; Myers, P.C. Wisconsin Univ., Madison Harvard-Smithsonian Center for Astrophysics, Cambridge, MA )

    1990-11-01

    A multi-epoch 5 GHz survey of candidate or confirmed weak T Tauri stars in the Taurus-Auriga molecular cloud complex was conducted with the Very Large Array. The stars were chosen from those having detectable X-ray or chromospheric emission, and weak-emission-line pre-main-sequence stars found by other means. Snapshots of 99 VLA fields containing 119 candidate stars were obtained with a sensitivity of 0.7 mJy; most fields were observed on two or three dates. Nine radio sources coincident with cataloged stars were found. One may be an RS CVn binary system; the other eight are pre-main-sequence stars. Three of the detected stars - HD 283447, V410 Tau, and FK X-ray 1 - were previously known radio sources. Five new detections are Herbig's Anon 1, Hubble 4, HDE 283572, Elias 12, and HK Tau/c. At least five of the sources are variable, and no linear or circular polarization was found. Several lines of evidence suggest that the radio-detected weak T Tauri stars are quite young, perhaps younger on average than nondetected stars. 54 refs.

  2. SELF-CALIBRATION OF GRAVITATIONAL SHEAR-GALAXY INTRINSIC ELLIPTICITY CORRELATION IN WEAK LENSING SURVEYS

    SciTech Connect

    Zhang Pengjie

    2010-09-10

    The galaxy intrinsic alignment is a severe challenge to precision cosmic shear measurement. We propose self-calibrating the induced gravitational shear-galaxy intrinsic ellipticity correlation (the GI correlation) in weak lensing surveys with photometric redshift measurements. (1) We propose a method to extract the intrinsic ellipticity-galaxy density cross-correlation (I-g) from the galaxy ellipticity-density measurement in the same redshift bin. (2) We also find a generic scaling relation to convert the extracted I-g correlation to the necessary GI correlation. We perform a concept study under simplified conditions and demonstrate its capability to significantly reduce GI contamination. We discuss the impact of various complexities on the two key ingredients of the self-calibration technique, namely the method for extracting the I-g correlation and the scaling relation between the I-g and the GI correlation. We expect that none of them will likely be able to completely invalidate the proposed self-calibration technique.

  3. Eikonal approximation, Finsler structures, and implications for Lorentz-violating photons in weak gravitational fields

    NASA Astrophysics Data System (ADS)

    Schreck, M.

    2015-12-01

    In the current article, the classical analog of the minimal photon sector in the Lorentz-violating Standard-Model extension (SME) is investigated. The analysis is based on describing a photon classically by a geometric ray that satisfies the eikonal equation. The action principle, which leads to the eikonal equation in conventional optics, is demonstrated to work in most (but not all) Lorentz-violating cases as well. Furthermore it is found that the integrands of the action functional correspond to Finsler structures. Based on these results, Lorentz-violating light rays in a weak gravitational background are treated through the use of the minimal-coupling principle. This allows for obtaining sensitivities on Lorentz violation in the photon sector by measurements of light bending at massive bodies such as the Sun. The computations are carried out for the currently running ESA mission GAIA and the planned NASA/ESA mission LATOR. Finally, a range of aspects of explicit Lorentz violation for photons is discussed in the Finsler setting.

  4. Neutron star equilibrium configurations within a fully relativistic theory with strong, weak, electromagnetic, and gravitational interactions

    NASA Astrophysics Data System (ADS)

    Belvedere, Riccardo; Pugliese, Daniela; Rueda, Jorge A.; Ruffini, Remo; Xue, She-Sheng

    2012-06-01

    We formulate the equations of equilibrium of neutron stars taking into account strong, weak, electromagnetic, and gravitational interactions within the framework of general relativity. The nuclear interactions are described by the exchange of the σ, ω, and ρ virtual mesons. The equilibrium conditions are given by our recently developed theoretical framework based on the Einstein-Maxwell-Thomas-Fermi equations along with the constancy of the general relativistic Fermi energies of particles, the "Klein potentials", throughout the configuration. The equations are solved numerically in the case of zero temperatures and for selected parameterizations of the nuclear models. The solutions lead to a new structure of the star: a positively charged core at supranuclear densities surrounded by an electronic distribution of thickness ˜ℏ/(mec)˜102ℏ/(mπc) of opposite charge, as well as a neutral crust at lower densities. Inside the core there is a Coulomb potential well of depth ˜mπc2/e. The constancy of the Klein potentials in the transition from the core to the crust, imposes the presence of an overcritical electric field ˜(Ec, the critical field being Ec=me2c3/(eℏ). The electron chemical potential and the density decrease, in the boundary interface, until values μecrust<μecore and ρ<ρ. For each central density, an entire family of core-crust interface boundaries and, correspondingly, an entire family of crusts with different mass and thickness, exist. The configuration with ρ=ρ˜4.3×1011 gcm separates neutron stars with and without inner crust. We present here the novel neutron star mass-radius for the especial case ρ=ρ and compare and contrast it with the one obtained from the traditional Tolman-Oppenheimer-Volkoff treatment.

  5. The Effect of Detector Nonlinearity on WFIRST PSF Profiles for Weak Gravitational Lensing Measurements

    NASA Astrophysics Data System (ADS)

    Plazas, A. A.; Shapiro, C.; Kannawadi, A.; Mandelbaum, R.; Rhodes, J.; Smith, R.

    2016-10-01

    Weak gravitational lensing (WL) is one of the most powerful techniques to learn about the dark sector of the universe. To extract the WL signal from astronomical observations, galaxy shapes must be measured and corrected for the point-spread function (PSF) of the imaging system with extreme accuracy. Future WL missions—such as NASA’s Wide-Field Infrared Survey Telescope (WFIRST)—will use a family of hybrid near-infrared complementary metal-oxide-semiconductor detectors (HAWAII-4RG) that are untested for accurate WL measurements. Like all image sensors, these devices are subject to conversion gain nonlinearities (voltage response to collected photo-charge) that bias the shape and size of bright objects such as reference stars that are used in PSF determination. We study this type of detector nonlinearity (NL) and show how to derive requirements on it from WFIRST PSF size and ellipticity requirements. We simulate the PSF optical profiles expected for WFIRST and measure the fractional error in the PSF size (ΔR/R) and the absolute error in the PSF ellipticity (Δe) as a function of star magnitude and the NL model. For our nominal NL model (a quadratic correction), we find that, uncalibrated, NL can induce an error of ΔR/R = 1 × 10-2 and Δe 2 = 1.75 × 10-3 in the H158 bandpass for the brightest unsaturated stars in WFIRST. In addition, our simulations show that to limit the bias of ΔR/R and Δe in the H158 band to ˜10% of the estimated WFIRST error budget, the quadratic NL model parameter β must be calibrated to ˜1% and ˜2.4%, respectively. We present a fitting formula that can be used to estimate WFIRST detector NL requirements once a true PSF error budget is established.

  6. Radio continuum detection in blue early-type weak-emission-line galaxies

    NASA Astrophysics Data System (ADS)

    Paswan, A.; Omar, A.

    2016-06-01

    The star formation rates (SFRs) in weak-emission-line (WEL) galaxies in a volume-limited (0.02 < z < 0.05) sample of blue early-type galaxies (ETGs) identified from the Sloan Digital Sky Survey, are constrained here using 1.4-GHz radio continuum emission. The direct detection of 1.4-GHz radio continuum emission is made in eight WEL galaxies and a median stacking is performed on 57 WEL galaxies using Very Large Array (VLA) Faint Images of Radio Sky at Twenty-cm (FIRST) images. The median stacked 1.4-GHz flux density and luminosity are estimated as 79 ± 19 μJy and 0.20 ± 0.05 × 1021 W Hz-1, respectively. The radio far-infrared correlation in four WEL galaxies suggests that the radio continuum emission from WEL galaxies is most likely a result of star formation activities. The median SFR for WEL galaxies is estimated as 0.23 ± 0.06 M⊙ yr-1, which is much less than SFRs (0.5-50 M⊙ yr-1) in purely star-forming blue ETGs. The SFRs in blue ETGs are found to be correlated with their stellar velocity dispersions (σ) and decreasing gradually beyond σ of ˜100 km s-1. This effect is most likely linked to the growth of a black hole and the suppression of star formation via active galactic nucleus (AGN) feedback. The colour differences between star-forming and WEL subtypes of blue ETGs appear to be driven to a large extent by the level of current star formation activities. In a likely scenario of an evolutionary sequence between subtypes, the observed colour distribution in blue ETGs can be explained best in terms of fast evolution through AGN feedback.

  7. Radio Emission from Weak Spherical Shocks in the Outskirts of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung

    2015-04-01

    In Kang (2015) we calculated the acceleration of cosmic-ray electrons at weak spherical shocks that are expected to form in the cluster outskirts, and estimated the diffuse synchrotron radiation emitted by those electrons. There we demonstrated that, at decelerating spherical shocks, the volume integrated spectra of both electrons and radiation deviate significantly from the test-particle power-laws predicted for constant planar shocks, because the shock compression ratio and the flux of inject electrons decrease in time. In this study, we consider spherical blast waves propagating through a constant density core surrounded by an isothermal halo with ρ∝ r^{-n} in order to explore how the deceleration of the shock affects the radio emission from accelerated electrons. The surface brightness profile and the volume-integrated radio spectrum of the model shocks are calculated by assuming a ribbon-like shock surface on a spherical shell and the associated downstream region of relativistic electrons. If the postshock magnetic field strength is about 0.7 or 7μG, at the shock age of ˜ 50 Myr, the volume-integrated radio spectrum steepens gradually with the spectral index from α_{inj} to α_{inj}+0.5 over 0.1-10 GHz, where α_{inj} is the injection index at the shock position expected from the diffusive shock acceleration theory. Such gradual steepening could explain the curved radio spectrum of the radio relic in cluster A2266, which was interpreted as a broken power-law by Trasatti et al. (2015), if the relic shock is young enough so that the break frequency is around 1$ GHz.

  8. Improved spacecraft radio science using an on-board atomic clock: Application to gravitational wave searches

    SciTech Connect

    Tinto, Massimo; Dick, George J.; Prestage, John D.; Armstrong, J. W.

    2009-05-15

    Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently leading noise sources: phase scintillation noise from the Earth's atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multilink CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of 3.7x10{sup -14} Hz{sup -1/2} for randomly polarized, monochromatic GW signals isotropically distributed over the celestial sphere, over a two-decade ({approx}0.0001-0.01 Hz) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to improve also other radio science experiments (i.e., tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.

  9. The generation of gravitational waves. 1. Weak-field sources: A plug-in-and-grind formalism

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.; Kovacs, S. J.

    1974-01-01

    A plug-in-and-grind formalism is derived for calculating the gravitational waves emitted by any system with weak internal gravitational fields. If the internal fields have negligible influence on the system's motions, then the formalism reduces to standard linearized theory. Whether or not gravity affects the motions, if the motions are slow and internal stresses are weak, then the new formalism reduces to the standard quadrupole-moment formalism. In the general case the new formalism expresses the radiation in terms of a retarded Green's function for slightly curved spacetime, and then breaks the Green's-function integral into five easily understood pieces: direct radiation, produced directly by the motions of the sources; whump radiation, produced by the the gravitational stresses of the source; transition radiation, produced by a time-changing time delay (Shapiro effect) in the propagation of the nonradiative, 1/r field of the source; focussing radiation produced when one portion of the source focusses, in a time-dependent way, the nonradiative field of another portion of the source, and tail radiation, produced by backscatter of the nonradiative field in regions of focussing.

  10. The intrinsic alignment of galaxies and its impact on weak gravitational lensing in an era of precision cosmology

    NASA Astrophysics Data System (ADS)

    Troxel, M. A.; Ishak, Mustapha

    2015-02-01

    The wealth of incoming and future cosmological observations will allow us to map out the structure and evolution of the observable universe to an unprecedented level of precision. Among these observations is the weak gravitational lensing of galaxies, e.g., cosmic shear that measures the minute distortions of background galaxy images by intervening cosmic structure. Weak lensing and cosmic shear promise to be a powerful probe of astrophysics and cosmology, constraining models of dark energy, measuring the evolution of structure in the universe, and testing theories of gravity on cosmic scales. However, the intrinsic alignment of galaxies-their shape and orientation before being lensed-may pose a great challenge to the use of weak gravitational lensing as an accurate cosmological probe, and has been identified as one of the primary physical systematic biases in cosmic shear studies. Correlations between this intrinsic alignment and the lensing signal can persist even for large physical separations, and isolating the effect of intrinsic alignment from weak lensing is not trivial. A great deal of work in the last two decades has been devoted to understanding and characterizing this intrinsic alignment, which is also a direct and complementary probe of structure formation and evolution in its own right. In this review, we report in a systematic way the state of our understanding of the intrinsic alignment of galaxies, with a particular emphasis on its large-scale impact on weak lensing measurements and methods for its isolation or mitigation. We begin with an introduction to the use of cosmic shear as a probe for cosmology and describe the various physical contributions by intrinsic alignment to the shear or convergence 2- and 3-point correlations. We then review developments in the modeling of the intrinsic alignment signal, including a trend toward attempting to incorporate more accurate nonlinear and single halo effects. The impact on cosmological constraints by the

  11. Detection of a Compact Radio Source near the Center of a Gravitational Lens: Quasar Image or Galactic Core?

    PubMed

    Gorenstein, M V; Shapiro, I I; Cohen, N L; Corey, B E; Falco, E E; Marcaide, J M; Rogers, A E; Whitney, A R; Porcas, R W; Preston, R A; Rius, A

    1983-01-01

    By use of a new, very sensitive interferometric system, a faint, compact radio source has been detected near the center of the galaxy that acts as the main part of a gravitational lens. This lens forms two previously discovered images of the quasar Q09S7+561, which lies in the direction of the constellation Ursa Major. The newly detected source has a core smaller than 0.002 arc second in diameter with a flux density of 0.6 +/- 0.1 millijansky at the 13-centimeter wavelength of the radio observations. This source could be the predicted third image of the transparent gravitational lens, the central core of the galaxy, or some combination of the two. It is not yet possible to choose reliably between these alternatives.

  12. Intranight optical variability of radio-quiet weak emission line quasars - IV

    NASA Astrophysics Data System (ADS)

    Kumar, Parveen; Chand, Hum; Gopal-Krishna

    2016-09-01

    We report an extension of our programme to search for radio-quiet BL Lac candidates using intranight optical variability (INOV) as a probe. The present INOV observations cover a well-defined representative set of 10 `radio-quiet weak-emission-line quasars' (RQWLQs), selected from a newly published sample of 46 such sources, derived from the Sloan Digital Sky Survey (Data release 7). Intranight CCD monitoring of the 10 RQWLQs was carried out in 18 sessions lasting at least 3.5 h. For each session, differential light curves of the target RQWLQ were derived relative to two steady comparison stars monitored simultaneously. Combining these new data with those already published by us for 15 RQWLQs monitored in 30 sessions, we estimate an INOV duty cycle of ˜3 per cent for the RQWLQs, which appears inconsistent with BL Lacs. However, the observed INOV events (which occurred in just two of the sessions) are strong (with a fractional variability amplitude ψ > 10 per cent), hence blazar-like. We briefly point out the prospects of an appreciable rise in the estimated INOV duty cycle for RQWLQs with a relatively modest increase in sensitivity for monitoring these rather faint objects.

  13. An experiment to verify that the weak interactions satisfy the strong equivalence principle. [electron capture and gravitational potential

    NASA Technical Reports Server (NTRS)

    Eby, P. B.

    1978-01-01

    The construction of a clock based on the beta decay process is proposed to test for any violations by the weak interaction of the strong equivalence principle bu determining whether the weak interaction coupling constant beta is spatially constant or whether it is a function of gravitational potential (U). The clock can be constructed by simply counting the beta disintegrations of some suitable source. The total number of counts are to be taken a measure of elapsed time. The accuracy of the clock is limited by the statistical fluctuations in the number of counts, N, which is equal to the square root of N. Increasing N gives a corresponding increase in accuracy. A source based on the electron capture process can be used so as to avoid low energy electron discrimination problems. Solid state and gaseous detectors are being considered. While the accuracy of this type of beta decay clock is much less than clocks based on the electromagnetic interaction, there is a corresponding lack of knowledge of the behavior of beta as a function of gravitational potential. No predictions from nonmetric theories as to variations in beta are available as yet, but they may occur at the U/sg C level.

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

    SciTech Connect

    Jackson, N.

    2011-09-20

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

  15. MULTI-MESSENGER ASTRONOMY OF GRAVITATIONAL-WAVE SOURCES WITH FLEXIBLE WIDE-AREA RADIO TRANSIENT SURVEYS

    SciTech Connect

    Yancey, Cregg C.; Shawhan, Peter; Bear, Brandon E.; Akukwe, Bernadine; Simonetti, John H.; Tsai, Jr-Wei; Chen, Kevin; Dowell, Jayce; Obenberger, Kenneth; Taylor, Gregory B.; Gough, Jonathan D.; Kanner, Jonah; Kavic, Michael

    2015-10-20

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of GWs and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, the Low Frequency Array and the Murchison Widefield Array. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a ∼30 s time window and ∼200–500 deg{sup 2} sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a prompt radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of ∼2. For some models, we also map the parameter space that may be constrained by non-detections.

  16. Multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys

    NASA Astrophysics Data System (ADS)

    Kavic, Michael; Cregg C. Yancey, Brandon E. Bear, Bernadine Akukwe, Kevin Chen, Jayce Dowell, Jonathan D. Gough, Jonah Kanner, Kenneth Obenberger, Peter Shawhan, John H. Simonetti , Gregory B. Taylor , Jr-Wei Tsai

    2016-01-01

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of GWs and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, the Low Frequency Array and the Murchison Widefield Array. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a ˜30 s time window and ˜200-500 deg(2) sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a prompt radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of ˜2. For some models, we also map the parameter space that may be constrained by non-detections.

  17. Multi-messenger Astronomy of Gravitational-wave Sources with Flexible Wide-area Radio Transient Surveys

    NASA Astrophysics Data System (ADS)

    Yancey, Cregg C.; Bear, Brandon E.; Akukwe, Bernadine; Chen, Kevin; Dowell, Jayce; Gough, Jonathan D.; Kanner, Jonah; Kavic, Michael; Obenberger, Kenneth; Shawhan, Peter; Simonetti, John H.; -Wei Tsai, Gregory B. Taylor, Jr.

    2015-10-01

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of GWs and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, the Low Frequency Array and the Murchison Widefield Array. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a ˜30 s time window and ˜200-500 deg2 sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a prompt radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of ˜2. For some models, we also map the parameter space that may be constrained by non-detections.

  18. Probing high-redshift clusters with HST/ACS gravitational weak-lensing and Chandra x-ray observations

    NASA Astrophysics Data System (ADS)

    Jee, Myungkook James

    2006-06-01

    Clusters of galaxies, the largest gravitationally bound objects in the Universe, are useful tracers of cosmic evolution, and particularly detailed studies of still-forming clusters at high-redshifts can considerably enhance our understanding of the structure formation. We use two powerful methods that have become recently available for the study of these distant clusters: spaced- based gravitational weak-lensing and high-resolution X-ray observations. Detailed analyses of five high-redshift (0.8 < z < 1.3) clusters are presented based on the deep Advanced Camera for Surveys (ACS) and Chandra X-ray images. We show that, when the instrumental characteristics are properly understood, the newly installed ACS on the Hubble Space Telescope (HST) can detect subtle shape distortions of background galaxies down to the limiting magnitudes of the observations, which enables the mapping of the cluster dark matter in unprecedented high-resolution. The cluster masses derived from this HST /ACS weak-lensing study have been compared with those from the re-analyses of the archival Chandra X-ray data. We find that there are interesting offsets between the cluster galaxy, intracluster medium (ICM), and dark matter centroids, and possible scenarios are discussed. If the offset is confirmed to be uniquitous in other clusters, the explanation may necessitate major refinements in our current understanding of the nature of dark matter, as well as the cluster galaxy dynamics. CL0848+4452, the highest-redshift ( z = 1.27) cluster yet detected in weak-lensing, has a significant discrepancy between the weak- lensing and X-ray masses. If this trend is found to be severe and common also for other X-ray weak clusters at redshifts beyond the unity, the conventional X-ray determination of cluster mass functions, often inferred from their immediate X-ray properties such as the X-ray luminosity and temperature via the so-called mass-luminosity (M-L) and mass-temperature (M-T) relations, will become

  19. The imprint of f(R) gravity on weak gravitational lensing - I. Connection between observables and large-scale structure

    NASA Astrophysics Data System (ADS)

    Higuchi, Yuichi; Shirasaki, Masato

    2016-07-01

    We study the effect of f(R) gravity on the statistical properties of various large-scale structures which can be probed in weak gravitational lensing measurements. A set of ray-tracing simulations of gravitational lensing in f(R) gravity enables us to explore cosmological information on (i) stacking analyses of weak lensing observables and (ii) peak statistics in reconstructed lensing mass maps. For the f(R) model proposed by Hu & Sawicki, the measured lensing signals of dark matter haloes in the stacking analysis would show a ≲10 per cent difference between the standard Λcold dark matter and the f(R) model when the additional degree of freedom in f(R) model would be |fR0| ˜ 10-5. Among various large-scale structures to be studied in stacking analysis, troughs, i.e. underdensity regions in projected plane of foreground massive haloes, could be promising to constrain the model with |fR0| ˜ 10-5, while stacking analysis around voids is found to be difficult to improve the constraint of |fR0| even in future lensing surveys with a sky coverage of ˜1000 deg2. On the peak statistics, we confirm the correspondence between local maxima and dark matter haloes along the line of sight, regardless of the modification of gravity in our simulation. Thus, the number count of high significance local maxima would be useful to probe the mass function of dark matter haloes even in the f(R) model with |fR0| ≲ 10-5. We also find that including local minima in lensing mass maps would be helpful to improve the constant on f(R) gravity down to |fR0| = 10-5 in ongoing weak lensing surveys.

  20. Gravitational perturbation of the BTZ black hole induced by test particles and weak cosmic censorship in AdS spacetime

    SciTech Connect

    Rocha, Jorge V.; Cardoso, Vitor

    2011-05-15

    We analyze the gravitational perturbations induced by particles falling into a three dimensional, asymptotically AdS black hole geometry. More specifically, we solve the linearized perturbation equations obtained from the geodesic motion of a ringlike distribution of test particles in the BTZ background. This setup ensures that the U(1) symmetry of the background is preserved. The nonasymptotic flatness of the background raises difficulties in attributing the significance of energy and angular momentum to the conserved quantities of the test particles. This issue is well known but, to the best of our knowledge, has never been addressed in the literature. We confirm that the naive expressions for energy and angular momentum are the correct definitions. Finally, we put an asymptotically AdS version of the weak cosmic censorship to a test: by attempting to overspin the BTZ black hole with test particles it is found that the black hole cannot be spun-up past its extremal limit.

  1. Gravitational lensing from compact bodies: Analytical results for strong and weak deflection limits

    SciTech Connect

    Amore, Paolo; Cervantes, Mayra; De Pace, Arturo; Fernandez, Francisco M.

    2007-04-15

    We develop a nonperturbative method that yields analytical expressions for the deflection angle of light in a general static and spherically symmetric metric. The method works by introducing into the problem an artificial parameter, called {delta}, and by performing an expansion in this parameter to a given order. The results obtained are analytical and nonperturbative because they do not correspond to a polynomial expression in the physical parameters. Already to first order in {delta} the analytical formulas obtained using our method provide at the same time accurate approximations both at large distances (weak deflection limit) and at distances close to the photon sphere (strong deflection limit). We have applied our technique to different metrics and verified that the error is at most 0.5% for all regimes. We have also proposed an alternative approach which provides simpler formulas, although with larger errors.

  2. Astronomical polarization studies at radio and infrared wavelengths. Part 1: Gravitational deflection of polarized radiation

    NASA Technical Reports Server (NTRS)

    Dennison, B. K.

    1976-01-01

    The gravitational field is probed in a search for polarization dependence in the light bending. This involves searching for a splitting of a source image into orthogonal polarizations as the radiation passes through the solar gravitational field. This search was carried out using the techniques of very long and intermediate baseline interferometry, and by seeking a relative phase delay in orthogonal polarizations of microwaves passing through the solar gravitational field. In this last technique a change in the total polarization of the Helios 1 carrier wave was sought as the spacecraft passed behind the sun. No polarization splitting was detected.

  3. The Red Radio Ring: a gravitationally lensed hyperluminous infrared radio galaxy at z = 2.553 discovered through the citizen science project SPACE WARPS

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    We report the discovery of a gravitationally lensed hyperluminous infrared galaxy (intrinsic LIR ≈ 1013 L⊙) with strong radio emission (intrinsic L1.4 GHz ≈ 1025 W Hz-1) at z = 2.553. The source was identified in the citizen science project SPACE WARPS through the visual inspection of tens of thousands of iJKs colour composite images of luminous red galaxies (LRGs), groups and clusters of galaxies and quasars. Appearing as a partial Einstein ring (re ≈ 3 arcsec) around an LRG at z = 0.2, the galaxy is extremely bright in the sub-millimetre for a cosmological source, with the thermal dust emission approaching 1 Jy at peak. The redshift of the lensed galaxy is determined through the detection of the CO(3→2) molecular emission line with the Large Millimetre Telescope's Redshift Search Receiver and through [O III] and Hα line detections in the near-infrared from Subaru/Infrared Camera and Spectrograph. We have resolved the radio emission with high-resolution (300-400 mas) eMERLIN L-band and Very Large Array C-band imaging. These observations are used in combination with the near-infrared imaging to construct a lens model, which indicates a lensing magnification of μ ≈ 10. The source reconstruction appears to support a radio morphology comprised of a compact (<250 pc) core and more extended component, perhaps indicative of an active nucleus and jet or lobe.

  4. CFHTLenS: the relation between galaxy dark matter haloes and baryons from weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Velander, Malin; van Uitert, Edo; Hoekstra, Henk; Coupon, Jean; Erben, Thomas; Heymans, Catherine; Hildebrandt, Hendrik; Kitching, Thomas D.; Mellier, Yannick; Miller, Lance; Van Waerbeke, Ludovic; Bonnett, Christopher; Fu, Liping; Giodini, Stefania; Hudson, Michael J.; Kuijken, Konrad; Rowe, Barnaby; Schrabback, Tim; Semboloni, Elisabetta

    2014-01-01

    We present a study of the relation between dark matter halo mass and the baryonic content of their host galaxies, quantified through galaxy luminosity and stellar mass. Our investigation uses 154 deg2 of Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) lensing and photometric data, obtained from the CFHT Legacy Survey. To interpret the weak lensing signal around our galaxies, we employ a galaxy-galaxy lensing halo model which allows us to constrain the halo mass and the satellite fraction. Our analysis is limited to lenses at redshifts between 0.2 and 0.4, split into a red and a blue sample. We express the relationship between dark matter halo mass and baryonic observable as a power law with pivot points of 10^{11} h_{70}^{-2} L_{{⊙}} and 2× 10^{11} h_{70}^{-2} M_{{⊙}} for luminosity and stellar mass, respectively. For the luminosity-halo mass relation, we find a slope of 1.32 ± 0.06 and a normalization of 1.19^{+0.06}_{-0.07}× 10^{13} h_{70}^{-1} M_{{⊙}} for red galaxies, while for blue galaxies the best-fitting slope is 1.09^{+0.20}_{-0.13} and the normalization is 0.18^{+0.04}_{-0.05}× 10^{13} h_{70}^{-1} M_{{⊙}}. Similarly, we find a best-fitting slope of 1.36^{+0.06}_{-0.07} and a normalization of 1.43^{+0.11}_{-0.08}× 10^{13} h_{70}^{-1} M_{{⊙}} for the stellar mass-halo mass relation of red galaxies, while for blue galaxies the corresponding values are 0.98^{+0.08}_{-0.07} and 0.84^{+0.20}_{-0.16}× 10^{13} h_{70}^{-1} M_{{⊙ }}. All numbers convey the 68 per cent confidence limit. For red lenses, the fraction which are satellites inside a larger halo tends to decrease with luminosity and stellar mass, with the sample being nearly all satellites for a stellar mass of 2× 109 h_{70}^{-2} M_{{⊙}}. The satellite fractions are generally close to zero for blue lenses, irrespective of luminosity or stellar mass. This, together with the shallower relation between halo mass and baryonic tracer, is a direct confirmation from galaxy

  5. MEASURING THE GEOMETRY OF THE UNIVERSE FROM WEAK GRAVITATIONAL LENSING BEHIND GALAXY GROUPS IN THE HST COSMOS SURVEY

    SciTech Connect

    Taylor, James E.; Massey, Richard J.; Leauthaud, Alexie; Tanaka, Masayuki; George, Matthew R.; Rhodes, Jason; Ellis, Richard; Scoville, Nick; Kitching, Thomas D.; Capak, Peter; Finoguenov, Alexis; Ilbert, Olivier; Kneib, Jean-Paul; Jullo, Eric; Koekemoer, Anton M.

    2012-04-20

    Gravitational lensing can provide pure geometric tests of the structure of spacetime, for instance by determining empirically the angular diameter distance-redshift relation. This geometric test has been demonstrated several times using massive clusters which produce a large lensing signal. In this case, matter at a single redshift dominates the lensing signal, so the analysis is straightforward. It is less clear how weaker signals from multiple sources at different redshifts can be stacked to demonstrate the geometric dependence. We introduce a simple measure of relative shear which for flat cosmologies separates the effect of lens and source positions into multiplicative terms, allowing signals from many different source-lens pairs to be combined. Applying this technique to a sample of groups and low-mass clusters in the COSMOS survey, we detect a clear variation of shear with distance behind the lens. This represents the first detection of the geometric effect using weak lensing by multiple, low-mass groups. The variation of distance with redshift is measured with sufficient precision to constrain the equation of state of the universe under the assumption of flatness, equivalent to a detection of a dark energy component {Omega}{sub X} at greater than 99% confidence for an equation-of-state parameter -2.5 {<=} w {<=} -0.1. For the case w = -1, we find a value for the cosmological constant density parameter {Omega}{sub {Lambda}} = 0.85{sup +0.044}{sub -}0{sub .19} (68% CL) and detect cosmic acceleration (q{sub 0} < 0) at the 98% CL. We consider the systematic uncertainties associated with this technique and discuss the prospects for applying it in forthcoming weak-lensing surveys.

  6. Nbody Simulations and Weak Gravitational Lensing using new HPC-Grid resources: the PI2S2 project

    NASA Astrophysics Data System (ADS)

    Becciani, U.; Antonuccio-Delogu, V.; Costa, A.; Comparato, M.

    2008-08-01

    We present the main project of the new grid infrastructure and the researches, that have been already started in Sicily and will be completed by next year. The PI2S2 project of the COMETA consortium is funded by the Italian Ministry of University and Research and will be completed in 2009. Funds are from the European Union Structural Funds for Objective 1 regions. The project, together with a similar project called Trinacria GRID Virtual Laboratory (Trigrid VL), aims to create in Sicily a computational grid for e-science and e-commerce applications with the main goal of increasing the technological innovation of local enterprises and their competition on the global market. PI2S2 project aims to build and develop an e-Infrastructure in Sicily, based on the grid paradigm, mainly for research activity using the grid environment and High Performance Computer systems. As an example we present the first results of a new grid version of FLY a tree Nbody code developed by INAF Astrophysical Observatory of Catania, already published in the CPC program Library, that will be used in the Weak Gravitational Lensing field.

  7. Viking radio science data analysis and synthesis. [rotation of Mars, solar system dynamics, and gravitational laws

    NASA Technical Reports Server (NTRS)

    Shapiro, I. I.

    1984-01-01

    The rotational motion of Mars and its geophysical ramifications were investigated. Solar system dynamics and the laws of gravitation were also studied. The planetary ephemeris program, which was the central element in data analysis for this project, is described in brief. Viking Lander data were used in the investigation.

  8. A weak gravitational lensing recalibration of the scaling relations linking the gas properties of dark haloes to their mass

    NASA Astrophysics Data System (ADS)

    Wang, Wenting; White, Simon D. M.; Mandelbaum, Rachel; Henriques, Bruno; Anderson, Michael E.; Han, Jiaxin

    2016-03-01

    We use weak gravitational lensing to measure mean mass profiles around locally brightest galaxies (LBGs). These are selected from the Seventh Data Release of the Sloan Digital Sky Survey spectroscopic and photometric catalogues to be brighter than any neighbour projected within 1.0 Mpc and differing in redshift by <1000 km s-1. Most (>83 per cent) are expected to be the central galaxies of their dark matter haloes. Previous stacking analyses have used this LBG sample to measure mean Sunyaev-Zeldovich flux and mean X-ray luminosity as a function of LBG stellar mass. In both cases, a simulation of the formation of the galaxy population was used to estimate effective halo mass for LBGs of given stellar mass, allowing the derivation of scaling relations between the gas properties of haloes and their mass. By comparing results from a variety of simulations to our lensing data, we show that this procedure has significant model dependence reflecting: (i) the failure of any given simulation to reproduce observed galaxy abundances exactly; (ii) a dependence on the cosmology underlying the simulation; and (iii) a dependence on the details of how galaxies populate haloes. We use our lensing results to recalibrate the scaling relations, eliminating most of this model dependence and explicitly accounting both for residual modelling uncertainties and for observational uncertainties in the lensing results. The resulting scaling relations link the mean gas properties of dark haloes to their mass over an unprecedentedly wide range, 1012.5 < M500/M⊙ < 1014.5, and should fairly and robustly represent the full halo population.

  9. The Viking relativity experiment. [radio transmission delay due to solar gravitation effects

    NASA Technical Reports Server (NTRS)

    Shapiro, I. I.; Reasenberg, R. D.; Macneil, P. E.; Goldstein, R. B.; Brenkle, J. P.; Cain, D. L.; Komarek, T.; Zygielbaum, A. I.; Cuddihy, W. F.; Michael, W. H., Jr.

    1977-01-01

    Measurements of the round-trip time of flight of radio signals transmitted from the earth to the Viking spacecraft are being analyzed to test the predictions of Einstein's theory of general relativity. According to this theory the signals will be delayed by up to approximately 250 microsec owing to the direct effect of solar gravity on the propagation. A very preliminary qualitative analysis of the Viking data obtained near the 1976 superior conjunction of Mars indicates agreement with the predictions to within the estimated uncertainty of 0.5%.

  10. DETECTION OF SUBSTRUCTURE IN THE GRAVITATIONALLY LENSED QUASAR MG0414+0534 USING MID-INFRARED AND RADIO VLBI OBSERVATIONS

    SciTech Connect

    MacLeod, Chelsea L.; Jones, Ramsey; Agol, Eric; Kochanek, Christopher S.

    2013-08-10

    We present 11.2 {mu}m observations of the gravitationally lensed, radio-loud z{sub s} = 2.64 quasar MG0414+0534, obtained using the Michelle camera on Gemini North. We find a flux ratio anomaly of A2/A1 = 0.93 {+-} 0.02 for the quasar images A1 and A2. When combined with the 11.7 {mu}m measurements from Minezaki et al., the A2/A1 flux ratio is nearly 5{sigma} from the expected ratio for a model based on the two visible lens galaxies. The mid-IR flux ratio anomaly can be explained by a satellite (substructure), 0.''3 northeast of image A2, as can the detailed very long baseline interferometry (VLBI) structures of the jet produced by the quasar. When we combine the mid-IR flux ratios with high-resolution VLBI measurements, we find a best-fit mass between 10{sup 6.2} and 10{sup 7.5} M{sub Sun} inside the Einstein radius for a satellite substructure modeled as a singular isothermal sphere at the redshift of the main lens (z{sub l} = 0.96). We are unable to set an interesting limit on the mass to light ratio due to its proximity to the quasar image A2. While the observations used here were technically difficult, surveys of flux anomalies in gravitational lenses with the James Webb Space Telescope will be simple, fast, and should well constrain the abundance of substructure in dark matter halos.

  11. The X-Ray Weakness of GPS Radio Galaxies: A Volume-Limited Complete Sample

    NASA Technical Reports Server (NTRS)

    Mushotsky, Richard (Technical Monitor); Siemiginowska, Aneta

    2005-01-01

    The XMM-Newton observations of the GPS sample was completed last summer. We are in process of finalizing the paper describing the data and the results. The main goal of the project was to determine the X-ray spectra of the GPS galaxies in comparison to regular radio galaxies. Our XMM observations show evidence that the GPS galaxies are heavily obscured with the large absorbing columns exceeding N(H)greater than le22 cm^-2. Taking into account the obscuration we determined that the intrinsic X-ray luminosities of GPS galaxies are of order le43-le44 erg/s, comparable to low luminosity radio loud quasars. The large GPS samples can confirm the result, as at this moment our evidence is based only on 7 GPS galaxies observed with good S/N/ in X-rays. The first paper summarizing the results of the XMM observation of Mkn 668 has been published Astronomy & Astrophysics. We found soft X-ray signatures of a hot plasma (kT approximately 10^7K) and a hard X-ray emission from the nucleus. The X-ray spectrum above 2.5-keV is characterized by a very flat (observed photon index, Gamma-0.5) power-law continuum, alongside with a strong Fe-K-alpha neutral iron fluorescent line (EW600-eV). The best explanation for the origin of this high energy X-ray emission is in terms of the Compton-reflection of the nuclear emission. The primary X-ray emission is obscured by a Compton-thick (N_H to 10^24 cm-2) matter which becomes transparent at higher energies. The observed above 2.5-keV X-rays are mostly due to reflection which is indicated by a strong Fe-K-alpha line. This source represented the second hard X-ray detection of the GPS galaxy ever (the first one being 1345+125; O'Dea et al. 2000). The observations of the other GPS galaxies in our sample confirmed the trend of the large obscuration present in the spectra. However, we do not have a compelling evidence for a hot gas in the nucleus. The two other GPS galaxies observed with Chandra were added to the total of 7 GPS galaxies. This GPS

  12. A Radio-Based Search finds no evidence for intrinsically weak TGFs in the Fermi GBM Data

    NASA Astrophysics Data System (ADS)

    Briggs, Michael; Omar, Kareem

    2016-04-01

    We analyze gamma-ray data from the Fermi Gamma-ray Burst Monitor (GBM) around the times of VLF radio sferics. The gamma-ray photons are time-aligned to the times of radio sferics, with correction for the light travel time to Fermi, and accumulated. Gamma-ray photons from TGFs already known from the standard GBM TGF offline search are excluded from the accumulation. We use sferic signals from both the World Wide Lightning Location Network (WWLLN) and the Earth Networks Total Lightning Network (ENTLN). No excess signal is found in the accumulation of the gamma-ray data for sferics within 400 km of the Fermi nadir. However, an excess of gamma-rays is found in the co-aligned signal for sferics between 400 and 800 km of the Fermi nadir. Our interpretation of this distance-dependent non-detection / detection pattern is that the standard GBM offline search for TGFs is missing some TGFs that are weak at Fermi due to distance from Fermi and that there is no evidence for a population of TGFs that are intrinsically fainter than the threshold of the search.

  13. Magnetoreception in the wood mouse (Apodemus sylvaticus): influence of weak frequency-modulated radio frequency fields

    PubMed Central

    Malkemper, E. Pascal; Eder, Stephan H. K.; Begall, Sabine; Phillips, John B.; Winklhofer, Michael; Hart, Vlastimil; Burda, Hynek

    2015-01-01

    The mammalian magnetic sense is predominantly studied in species with reduced vision such as mole-rats and bats. Far less is known about surface-dwelling (epigeic) rodents with well-developed eyes. Here, we tested the wood mouse Apodemus sylvaticus for magnetoreception using a simple behavioural assay in which mice are allowed to build nests overnight in a visually symmetrical, circular arena. The tests were performed in the ambient magnetic field or in a field rotated by 90°. When plotted with respect to magnetic north, the nests were bimodally clustered in the northern and southern sectors, clearly indicating that the animals used magnetic cues. Additionally, mice were tested in the ambient magnetic field with a superimposed radio frequency magnetic field of the order of 100 nT. Wood mice exposed to a 0.9 to 5 MHz frequency sweep changed their preference from north-south to east-west. In contrast to birds, however, a constant frequency field tuned to the Larmor frequency (1.33 MHz) had no effect on mouse orientation. In sum, we demonstrated magnetoreception in wood mice and provide first evidence for a radical-pair mechanism in a mammal. PMID:25923312

  14. Effect of the radio frequency discharge on the dust charging process in a weakly collisional and fully ionized plasma

    SciTech Connect

    Motie, Iman; Bokaeeyan, Mahyar

    2015-02-15

    A close analysis of dust charging process in the presence of radio frequency (RF) discharge on low pressure and fully ionized plasma for both weak and strong discharge's electric field is considered. When the electromagnetic waves pass throughout fully ionized plasma, the collision frequency of the plasma is derived. Moreover, the disturbed distribution function of plasma particles in the presence of the RF discharge is obtained. In this article, by using the Krook model, we separate the distribution function in two parts, the Maxwellian part and the perturbed part. The perturbed part of distribution can make an extra current, so-called the accretion rate of electron (or ion) current, towards a dust particle as a function of the average electron-ion collision frequency. It is proven that when the potential of dust grains increases, the accretion rate of electron current experiences an exponential reduction. Furthermore, the accretion rate of electron current for a strong electric field is relatively smaller than that for a weak electric field. The reasons are elaborated.

  15. Effect of the radio frequency discharge on the dust charging process in a weakly collisional and fully ionized plasma

    NASA Astrophysics Data System (ADS)

    Motie, Iman; Bokaeeyan, Mahyar

    2015-02-01

    A close analysis of dust charging process in the presence of radio frequency (RF) discharge on low pressure and fully ionized plasma for both weak and strong discharge's electric field is considered. When the electromagnetic waves pass throughout fully ionized plasma, the collision frequency of the plasma is derived. Moreover, the disturbed distribution function of plasma particles in the presence of the RF discharge is obtained. In this article, by using the Krook model, we separate the distribution function in two parts, the Maxwellian part and the perturbed part. The perturbed part of distribution can make an extra current, so-called the accretion rate of electron (or ion) current, towards a dust particle as a function of the average electron-ion collision frequency. It is proven that when the potential of dust grains increases, the accretion rate of electron current experiences an exponential reduction. Furthermore, the accretion rate of electron current for a strong electric field is relatively smaller than that for a weak electric field. The reasons are elaborated.

  16. The X-Ray Weakness of GPS Radio Galaxies: A Volume-Limited Complete Sample

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard F. (Technical Monitor); Siemiginowska, Aneta (Principal Investigator)

    2004-01-01

    The XMM observations of Mkn 668 have been analyzed. We found soft X-ray signatures of a hot plasma (kT approximately 10^7 approximately K) and a hard X-ray emission from the nucleus. The X-ray spectrum above 2.5 approximately keV is characterized by a very flat (observed photon index, Gamma approximately 0.5) power-law continuum, alongside with a strong Fe-K-alpha neutral iron fluorescent line (EW approximately 600 approximately eV). The best explanation for the origin of this high energy X-ray emission is in terms of the Compton-reflection of the nuclear emission. The primary X-ray emission is obscured by a Compton-thick (N_H approximately 10^24 approximately cm-2) matter which becomes transparent at higher energies. The observed above 2.5-keV X-rays are mostly due to reflection which is indicated by a strong Fe-K-alpha line. This represents the second hard X-ray detection of the GPS galaxy ever (the first one being 1345+125; O Dea et al. 2000). Interestingly, the both such trend is confirmed by our on going XMM-Newton observations of a larger GPS sample, it would lead us to looking into the question on how the dense nuclear environment impacts the nature and evolution of a GPS source, and more generally, on the history of radio power in the universe. The paper summarizing the results has been submitted to Astronomy and Astrophysics in December 2003.

  17. Gravitational lenses

    NASA Technical Reports Server (NTRS)

    Turner, Edwin L.

    1989-01-01

    Recent observational and theoretical investigations of gravitational-lens phenomena are reviewed, and sample numerical data are presented in tables. Particular attention is given to luminous arcs, radio rings, galaxy-quasar associations, the problem of deriving actually or practically unique models of individual lens systems, and time delays and the Hubble constant.

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

    NASA Astrophysics Data System (ADS)

    Doyen, G.; Drakova, D.

    2015-08-01

    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 characteristics 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 gravonons are localized in the environment of the massive particles which generate them. The solution of the Schrödinger 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 at present cannot be controlled experimentally and therefore let the choice 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 depend on subtleties of the gravonon structure which at present cannot be controlled experimentally and therefore let the telegraph-like jumps 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 CQM 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

  19. A new giant luminous arc gravitational lens associated with a z = 0.62 galaxy cluster, and the environments of distant radio galaxies

    NASA Technical Reports Server (NTRS)

    Dickinson, Mark

    1993-01-01

    In the course of a survey investigating the cluster environments of distant 3CR radio galaxies, I have identified a previously unknown 'giant luminous arc' gravitational lens. The lensing cluster is associated with the radio galaxy 3C 220.1 at z = 0.62 and is the most distant cluster now known to produce such arcs. I present imaging and spectroscopic observations of the cluster and the arc, and discuss the implications for the cluster mass. At z greater than 0.6 the cluster velocity dispersions implied by such giant arcs may provide an interesting constraint on theories of large scale structure formation. The parent investigation in which this arc was identified concerns galaxy clusters and radio galaxy environments at 0.35 less than z less than 0.8. At the present epoch, powerful FR 2 radio galaxies tend to be found in environments of poor or average galaxy density. In contrast, at the higher redshifts investigated here, richer group and cluster environments are common. I present additional data on other clusters from this survey, and discuss its extension to z greater than 1 through a program of near-infrared and optical imaging.

  20. The Systematic Error Test for PSF Correction in Weak Gravitational Lensing Shear Measurement By the ERA Method By Idealizing PSF

    NASA Astrophysics Data System (ADS)

    Okura, Yuki; Futamase, Toshifumi

    2016-08-01

    We improve the ellipticity of re-smeared artificial image (ERA) method of point-spread function (PSF) correction in a weak lensing shear analysis in order to treat the realistic shape of galaxies and the PSF. This is done by re-smearing the PSF and the observed galaxy image using a re-smearing function (RSF) and allows us to use a new PSF with a simple shape and to correct the PSF effect without any approximations or assumptions. We perform a numerical test to show that the method applied for galaxies and PSF with some complicated shapes can correct the PSF effect with a systematic error of less than 0.1%. We also apply the ERA method for real data of the Abell 1689 cluster to confirm that it is able to detect the systematic weak lensing shear pattern. The ERA method requires less than 0.1 or 1 s to correct the PSF for each object in a numerical test and a real data analysis, respectively.

  1. Global VLBI Observations of Weak Extragalactic Radio Sources: Imaging Candidates to Align the VLBI and Gaia Frames

    NASA Technical Reports Server (NTRS)

    Bourda, Geraldine; Collioud, Arnaud; Charlot, Patrick; Porcas, Richard; Garrington, Simon

    2010-01-01

    The space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be important to align the Gaia and VLBI frames (International Celestial Reference Frame) with the highest accuracy. In this respect, it is found that only 10% of the ICRF sources are suitable to establish this link (70 sources), either because most of the ICRF sources are not bright enough at optical wavelengths or because they show extended radio emission which precludes reaching the highest astrometric accuracy. In order to improve the situation, we initiated a multi-step VLBI observational project, dedicated to finding additional suitable radio sources for aligning the two frames. The sample consists of about 450 optically-bright radio sources, typically 20 times weaker than the ICRF sources, which have been selected by cross-correlating optical and radio catalogs. The initial observations, aimed at checking whether these sources are detectable with VLBI, and conducted with the European VLBI Network (EVN) in 2007, showed an excellent 90% detection rate. This paper reports on global VLBI observations carried out in March 2008 to image 105 from the 398 previously detected sources. All sources were successfully imaged, revealing compact VLBI structure for about half of them, which is very promising for the future.

  2. Mergers of Charged Black Holes: Gravitational-wave Events, Short Gamma-Ray Bursts, and Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2016-08-01

    The discoveries of GW150914, GW151226, and LVT151012 suggest that double black hole (BH-BH) mergers are common in the universe. If at least one of the two merging black holes (BHs) carries a certain amount of charge, possibly retained by a rotating magnetosphere, the inspiral of a BH-BH system would drive a global magnetic dipole normal to the orbital plane. The rapidly evolving magnetic moment during the merging process would drive a Poynting flux with an increasing wind power. The magnetospheric activities during the final phase of the merger would make a fast radio burst (FRB) if the BH charge can be as large as a factor of \\hat{q}˜ ({10}-9{--}{10}-8) of the critical charge Q c of the BH. At large radii, dissipation of the Poynting flux energy in the outflow would power a short-duration high-energy transient, which would appear as a detectable short-duration gamma-ray burst (GRB) if the charge can be as large as \\hat{q}˜ ({10}-5{--}{10}-4). The putative short GRB coincident with GW150914 recorded by Fermi GBM may be interpreted with this model. Future joint GW/GRB/FRB searches would lead to a measurement or place a constraint on the charges carried by isolate BHs.

  3. Mergers of Charged Black Holes: Gravitational-wave Events, Short Gamma-Ray Bursts, and Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2016-08-01

    The discoveries of GW150914, GW151226, and LVT151012 suggest that double black hole (BH–BH) mergers are common in the universe. If at least one of the two merging black holes (BHs) carries a certain amount of charge, possibly retained by a rotating magnetosphere, the inspiral of a BH–BH system would drive a global magnetic dipole normal to the orbital plane. The rapidly evolving magnetic moment during the merging process would drive a Poynting flux with an increasing wind power. The magnetospheric activities during the final phase of the merger would make a fast radio burst (FRB) if the BH charge can be as large as a factor of \\hat{q}˜ ({10}-9{--}{10}-8) of the critical charge Q c of the BH. At large radii, dissipation of the Poynting flux energy in the outflow would power a short-duration high-energy transient, which would appear as a detectable short-duration gamma-ray burst (GRB) if the charge can be as large as \\hat{q}˜ ({10}-5{--}{10}-4). The putative short GRB coincident with GW150914 recorded by Fermi GBM may be interpreted with this model. Future joint GW/GRB/FRB searches would lead to a measurement or place a constraint on the charges carried by isolate BHs.

  4. Omnidirectional Gravitational Radiation Observatory: Proceedings of the First International Workshop

    NASA Astrophysics Data System (ADS)

    Velloso, W. F.; Aguiar, O. D.; Magalhães, N. S.

    1997-08-01

    The Table of Contents for the full book PDF is as follows: * Foreword * Introduction: The OMNI-1 Workshop and the beginning of the International Gravitational Radiation Observatory * Opening Talks * Gravitational radiation sources for Acoustic Detectors * The scientific and technological benefits of gravitational wave research * Operating Second and Third Generation Resonant-Mass Antennas * Performance of the ALLEGRO detector -- and what our experience tells us about spherical detectors * The Perth Niobium resonant mass antenna with microwave parametric transducer * The gravitational wave detectors EXPLORER and NAUTILUS * Gravitational Waves and Astrophysical Sources for the Next Generation Observatory * What is the velocity of gravitational waves? * Superstring Theory: how it change our ideas about the nature of Gravitation * Statistical approach to the G.W. emission from radio pulsars * Gravitational waves from precessing millisecond pulsars * The production rate of compact binary G.W. sources in elliptical galaxies * On the possibility to detect Gravitational Waves from precessing galactic neutron stars * Gravitational wave output of the head-on collision of two black holes * SN as a powerfull source of gravitational radiation * Long thick cosmic strings radiating gravitational waves and particles * Non-Parallel Electric and Magnetic Fields in a gravitational background, stationary G.W. and gravitons * Exact solutions of gravitational waves * Factorization method for linearized quantum gravity at tree-level. Graviton, photon, electron processes * Signal Detection with Resonant-Mass Antennas * Study of coalescing binaries with spherical gravitational waves detectors * Influence of transducer asymmetries on the isotropic response of a spherical gravitational wave antenna * Performances and preliminary results of the cosmic-ray detector associated with NAUTILUS * Possible transducer configurations for a spherical gravitational wave antenna * Detectability of

  5. Strong Gravitational Lensing with SNAP

    NASA Astrophysics Data System (ADS)

    Blandford, R. D.; Koopmans, L. V. E.

    2001-12-01

    As currently configured, SNAP should cover an area of sky to sufficient depth to observe tens of thousands of strong (ie multiple-imaging) gravitational lenses. This could provide an unprecedented database for performing cosmography, studies of large scale structure and galactic structure.and should complement the weak lensing program which will concentrate on larger scales. The challenge will be to recognize multiple imaging efficiently in an unbiased way and to organize effective follow up so as to obtain spectroscopic redshifts and monitor variable sources, when appropriate. Experience with the CLASS radio survey and the CASTLES program will be invaluable as we transition from the detailed study of a few tens of strong lenses through the ACS ultra-deep, deep and wide surveys (which should yield hundreds of examples of multiple imaging) to the larger samples envisaged from SNAP. New approaches to data analysis will be needed and coordinated planning with other proposed large survey instruments, like SKA, will be essential.

  6. The Origin of Gravitation

    NASA Astrophysics Data System (ADS)

    Zheng, Sheng Ming

    2012-10-01

    In the natural world, people have discovered four kinds of forces: electromagnetic force, gravitation, weak force, and strong force. Although the gravitation has been discovered more than three hundred years, its mechanism of origin is unclear until today. While investigating the origin of gravitation, I do some experiments discover the moving photons produce gravitation. This discovery shows the origin of gravitation. Meanwhile I do some experiments discover the light interference fringes are produced by the gravitation: my discovery demonstrate light is a particle, but is not a wave-particle duality. Furthermore, applications of this discovery to other moving particles show a similar effect. In a word: the micro particle moving produce gravitation and electromagnetic force. Then I do quantity experiment get a general formula: Reveal the essence of gravitational mass and the essence of electric charge; reveal the origin of gravitation and the essence of matter wave. Along this way, I unify the gravitation and electromagnetic force. Namely I find a natural law that from atomic world to star world play in moving track. See website: https://www.lap-publishing.com/catalog/details/store/gb/book/978-3-8473-2658-8/mechanism-of-interaction-in-moving-matter

  7. Gravitational lenses

    SciTech Connect

    Turner, E.L.

    1988-07-01

    For several years astronomers have devoted considerable effort to finding and studying a class of celestial phenomena whose very existence depends on rare cosmic accidents. These are gravitational-lens events, which occur when two or more objects at different distances from the earth happen to lie along the same line of sight and so coincide in the sky. The radiation from the more distant object, typically a quasar, is bent by the gravitational field of the foreground object. The bending creates a cosmic mirage: distorted or multiple images of the background object. Such phenomena may reveal many otherwise undetectable features of the image source, of the foreground object and of the space lying between them. Such observations could help to resolve several fundamental questions in cosmology. In the past decade theoretical and observational research on gravitational lenses has grown rapidly and steadily. At this writing at least 17 candidate lens systems have been discussed in the literature. Of the 17 lens candidates reported so far in professional literature, only five are considered to have been reliably established by subsequent observations. Another three are generally regarded as weak or speculative cases with less than 50 percent chance of actually being lens systems. In the remaining nine cases the evidence is mixed or is sparse enough so that the final judgment could swing either way. As might be concluded, little of the scientific promise of gravitational lenses has yet been realized. The work has not yielded a clear value for the proportionality constant or any of the other fundamental cosmological parameter. 7 figs.

  8. Basal electric and magnetic fields of celestial bodies come from positive-negative charge separation caused by gravitation of quasi-Casimir pressure in weak interaction

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Guang

    According to f =d(mv)/dt=m(dv/dt)+ v(dm/dt), a same gravitational formula had been de-duced from the variance in physical mass of QFT and from the variance in mass of inductive energy-transfer of GR respectively: f QF T = f GR = -G (mM/r2 )((r/r)+(v/c)) when their interaction-constants are all taken the experimental values (H05-0029-08, E15-0039-08). f QF T is the quasi-Casimir pressure. f GR is equivalent to Einstein's equation, then more easy to solve it. The hypothesis of the equivalent principle is not used in f QF T , but required by f GR . The predictions of f QF T and f GR are identical except that f QF T has quantum effects but f GR has not and f GR has Lense-Thirring effect but f QF T has not. The quantum effects of gravitation had been verified by Nesvizhevsky et al with the ultracold neutrons falling in the earth's gravitational field in 2002. Yet Lense-Thirring effect had not been measured by GP-B. It shows that f QF T is essential but f GR is phenomenological. The macro-f QF T is the statistic average pressure collided by net virtual neutrinos ν 0 flux (after self-offset in opposite directions) and in direct proportion to the mass. But micro-f QF T is in direct proportion to the scattering section. The electric mass (in inverse proportion to de Broglie wavelength λ) far less than nucleonic mass and the electric scattering section (in direct proportion to λ2 ) far large than that of nucleon, then the net ν 0 flux pressure exerted to electron far large than that to nucleon and the electric displacement far large than that of nucleon, it causes the gravitational polarization of positive-negative charge center separation. Because the gravity far less than the electromagnetic binding force, in atoms the gravitational polarization only produces a little separation. But the net ν 0 flux can press a part freedom electrons in plasma of ionosphere into the earth's surface, the static electric force of redundant positive ions prevents electrons from further

  9. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars. PMID:17836594

  10. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars.

  11. A new method for point-spread function correction using the ellipticity of re-smeared artificial images in weak gravitational lensing shear analysis

    SciTech Connect

    Okura, Yuki; Futamase, Toshifumi E-mail: tof@astr.tohoku.ac.jp

    2014-09-10

    Highly accurate weak lensing analysis is urgently required for planned cosmic shear observations. For this purpose we have eliminated various systematic noises in the measurement. The point-spread function (PSF) effect is one of them. A perturbative approach for correcting the PSF effect on the observed image ellipticities has been previously employed. Here we propose a new non-perturbative approach for PSF correction that avoids the systematic error associated with the perturbative approach. The new method uses an artificial image for measuring shear which has the same ellipticity as the lensed image. This is done by re-smearing the observed galaxy images and observed star images (PSF) with an additional smearing function to obtain the original lensed galaxy images. We tested the new method with simple simulated objects that have Gaussian or Sérsic profiles smeared by a Gaussian PSF with sufficiently large size to neglect pixelization. Under the condition of no pixel noise, it is confirmed that the new method has no systematic error even if the PSF is large and has a high ellipticity.

  12. Quasars and gravitational lenses.

    PubMed

    Turner, E L

    1984-03-23

    Despite the expenditure of large amounts of telescope time and other resources, most of the fundamental questions concerning quasi-stellar objects (quasars) remain unanswered. A complex phenomenology of radio, infrared, optical, and x-ray properties has accumulated but has not yielded even a satisfactory classification system. The large red shifts (distances) of quasars make them very valuable tools for studying cosmology and the properties of intervening matter in the Universe through observations of absorption lines and gravitational lenses.

  13. An Introduction to Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Burke, Bernard F.; Graham-Smith, Francis

    2009-09-01

    Preface; 1. Introduction; 2. The nature of the radio signal; 3. Signals, noise, radiometers and spectrometers; 4. Single-aperture radio telescopes; 5. The two-element interferometer; 6. Aperture synthesis; 7. Radiation, propagation and absorption of radio waves; 8. The local universe; 9. The interstellar medium; 10. Galactic dynamics; 11. Stars; 12. Pulsars; 13. Radio galaxies and quasars; 14. Cosmology fundamentals; 15. The angular structure of the CMB; 16. Cosmology: discrete radio sources and gravitational lensing; 17. The future of radio astronomy; Appendixes; References; Index.

  14. An Introduction to Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Burke, Bernard F.; Graham-Smith, Francis

    2014-02-01

    Preface; 1. Introduction; 2. The nature of the radio signal; 3. Signals, noise, radiometers and spectrometers; 4. Single-aperture radio telescopes; 5. The two-element interferometer; 6. Aperture synthesis; 7. Radiation, propagation and absorption of radio waves; 8. The local universe; 9. The interstellar medium; 10. Galactic dynamics; 11. Stars; 12. Pulsars; 13. Radio galaxies and quasars; 14. Cosmology fundamentals; 15. The angular structure of the CMB; 16. Cosmology: discrete radio sources and gravitational lensing; 17. The future of radio astronomy; Appendixes; References; Index.

  15. Gravitation research

    NASA Technical Reports Server (NTRS)

    Weiss, R.; Muehlner, D. J.; Benford, R. L.; Owens, D. K.; Pierre, N. A.; Rosenbluh, M.

    1972-01-01

    Balloon measurements were made of the far infrared background radiation. The radiometer used and its calibration are discussed. An electromagnetically coupled broadband gravitational antenna is also considered. The proposed antenna design and noise sources in the antenna are reviewed. A comparison is made between interferometric broadband and resonant bar antennas for the detection of gravitational wave pulses.

  16. Gravitational energy

    NASA Astrophysics Data System (ADS)

    Katz, Joseph

    2005-12-01

    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', EM, for those observers. If Mc2 is the total mass energy, the difference Mc2 - EM is the binding gravitational energy. Misner, Thorne and Wheeler (MTW) evaluated the gravitational energy of a spherically symmetric static spacetime. Here we show how to calculate gravitational energy in any static and stationary spacetimes with 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.

  17. History of Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1970-07-01

    While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.

  18. The gravitational wave experiment

    NASA Technical Reports Server (NTRS)

    Bertotti, B.; Ambrosini, R.; Asmar, S. W.; Brenkle, J. P.; Comoretto, G.; Giampieri, G.; Less, L.; Messeri, A.; Wahlquist, H. D.

    1992-01-01

    Since the optimum size of a gravitational wave detector is the wave length, interplanetary dimensions are needed for the mHz band of interest. Doppler tracking of Ulysses will provide the most sensitive attempt to date at the detection of gravitational waves in the low frequency band. The driving noise source is the fluctuations in the refractive index of interplanetary plasma. This dictates the timing of the experiment to be near solar opposition and sets the target accuracy for the fractional frequency change at 3.0 x 10 exp -14 for integration times of the order of 1000 sec. The instrumentation utilized by the experiment is distributed between the radio systems on the spacecraft and the seven participating ground stations of the Deep Space Network and Medicina. Preliminary analysis is available of the measurements taken during the Ulysses first opposition test.

  19. Numerical simulation of gravitational lenses

    NASA Astrophysics Data System (ADS)

    Cherniak, Yakov

    Gravitational lens is a massive body or system of bodies with gravitational field that bends directions of light rays propagating nearby. This may cause an observer to see multiple images of a light source, e.g. a star, if there is a gravitational lens between the star and the observer. Light rays that form each individual image may have different distances to travel, which creates time delays between them. In complex gravitational fields generated by the system of stars, analytical calculation of trajectories and light intensities is virtually impossible. Gravitational lens of two massive bodies, one behind another, are able to create four images of a light source. Furthermore, the interaction between the four light beams can form a complicated interference pattern. This article provides a brief theory of light behavior in a gravitational field and describes the algorithm for constructing the trajectories of light rays in a gravitational field, calculating wave fronts and interference pattern of light. If you set gravitational field by any number of transparent and non- transparent objects (stars) and set emitters of radio wave beams, it is possible to calculate the interference pattern in any region of space. The proposed method of calculation can be applied even in the case of the lack of continuity between the position of the emitting stars and position of the resulting image. In this paper we propose methods of optimization, as well as solutions for some problems arising in modeling of gravitational lenses. The simulation of light rays in the sun's gravitational field is taken as an example. Also caustic is constructed for objects with uniform mass distribution.

  20. Gravitating Hopfions

    SciTech Connect

    Shnir, Ya. M.

    2015-12-15

    We construct solutions of the 3 + 1 dimensional Faddeev–Skyrme model coupled to Einstein gravity. The solutions are static and asymptotically flat. They are characterized by a topological Hopf number. We investigate the dependence of the ADM masses of gravitating Hopfions on the gravitational coupling. When gravity is coupled to flat space solutions, a branch of gravitating Hopfion solutions arises and merges at a maximal value of the coupling constant with a second branch of solutions. This upper branch has no flat space limit. Instead, in the limit of a vanishing coupling constant, it connects to either the Bartnik–McKinnon or a generalized Bartnik–McKinnon solution. We further find that in the strong-coupling limit, there is no difference between the gravitating solitons of the Skyrme model and the Faddeev–Skyrme model.

  1. Radio Galaxies.

    ERIC Educational Resources Information Center

    Downes, Ann

    1986-01-01

    Provides background information on radio galaxies. Topic areas addressed include: what produces the radio emission; radio telescopes; locating radio galaxies; how distances to radio galaxies are found; physics of radio galaxies; computer simulations of radio galaxies; and the evolution of radio galaxies with cosmic time. (JN)

  2. Weak and compact radio emission in early massive star formation regions: an ionized jet toward G11.11–0.12P1

    SciTech Connect

    Rosero, V.; Hofner, P.; McCoy, M.; Kurtz, S.; Loinard, L.; Carrasco-González, C.; Rodríguez, L. F.; Menten, K. M.; Wyrowski, F.; Araya, E. D.; Cesaroni, R.; Ellingsen, S. P.

    2014-12-01

    We report 1.3 cm and 6 cm continuum observations toward the massive proto-stellar candidate G11.11–0.12P1 using the Karl G. Jansky Very Large Array. We detect a string of four unresolved radio continuum sources coincident with the mid-infrared source in G11P1. The continuum sources have positive spectral indices consistent with a thermal (free-free) ionized jet. The most likely origins of the ionized gas are shocks due to the interaction of a stellar wind with the surrounding high-density material. We also present NIR United Kingdom Infrared Telescope (UKIRT) archival data that show an extended structure detected only at K band (2.2 μm), which is oriented perpendicular to the jet, and that may be scattered light from a circumstellar disk around the massive protostar. Our observations plus the UKIRT archival data thus provide new evidence that a disk/jet system is present in the massive proto-stellar candidate located in the G11.11–0.12P1 core.

  3. Gravitational waves from gravitational collapse

    SciTech Connect

    Fryer, Christopher L; New, Kimberly C

    2008-01-01

    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.

  4. Probing gravitational dark matter

    NASA Astrophysics Data System (ADS)

    Ren, Jing; He, Hong-Jian

    2015-03-01

    So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to the gravitational interactions of DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle χs. It is a Bbb Z2 odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, ξsχs2Script R, where ξs is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction ξsχs2Script R, together with Higgs-curvature nonminimal coupling term ξhH†HScript R, induces effective couplings between χs2 and SM fields, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.

  5. Probing gravitational dark matter

    SciTech Connect

    Ren, Jing; He, Hong-Jian

    2015-03-27

    So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to the gravitational interactions of DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle χ{sub s}. It is a ℤ{sub 2} odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, ξ{sub s}χ{sub s}{sup 2}R, where ξ{sub s} is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction ξ{sub s}χ{sub s}{sup 2}R, together with Higgs-curvature nonminimal coupling term ξ{sub h}H{sup †}HR, induces effective couplings between χ{sub s}{sup 2} and SM fields, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.

  6. Gravitational quantum states of Antihydrogen

    SciTech Connect

    Voronin, A. Yu.; Froelich, P.; Nesvizhevsky, V. V.

    2011-03-15

    We present a theoretical study of the motion of the antihydrogen atom (H) in the gravitational field of Earth above a material surface. We predict that the H atom, falling in the gravitational field of Earth above a material surface, would settle into long-lived quantum states. We point out a method of measuring the difference in the energy of H in such states. The method allows for spectroscopy of gravitational levels based on atom-interferometric principles. We analyze the general feasibility of performing experiments of this kind. We point out that such experiments provide a method of measuring the gravitational force (Mg) acting on H and that they might be of interest in the context of testing the weak equivalence principle for antimatter.

  7. RESOLVING THE BRIGHT HCN(1–0) EMISSION TOWARD THE SEYFERT 2 NUCLEUS OF M51: SHOCK ENHANCEMENT BY RADIO JETS AND WEAK MASING BY INFRARED PUMPING?

    SciTech Connect

    Matsushita, Satoki; Trung, Dinh-V-; Boone, Frédéric; Krips, Melanie; Lim, Jeremy; Muller, Sebastien

    2015-01-20

    We present high angular resolution observations of the HCN(1-0) emission (at ∼1'' or ∼34 pc), together with CO J = 1-0, 2-1, and 3-2 observations, toward the Seyfert 2 nucleus of M51 (NGC 5194). The overall HCN(1-0) distribution and kinematics are very similar to that of the CO lines, which have been indicated as the jet-entrained molecular gas in our past observations. In addition, high HCN(1-0)/CO(1-0) brightness temperature ratio of about unity is observed along the jets, similar to that observed at the shocked molecular gas in our Galaxy. These results strongly indicate that both diffuse and dense gases are entrained by the jets and outflowing from the active galactic nucleus. The channel map of HCN(1-0) at the systemic velocity shows a strong emission right at the nucleus, where no obvious emission has been detected in the CO lines. The HCN(1-0)/CO(1-0) brightness temperature ratio at this region reaches >2, a value that cannot be explained considering standard physical/chemical conditions. Based on our calculations, we suggest infrared pumping and possibly weak HCN masing, but still requiring an enhanced HCN abundance for the cause of this high ratio. This suggests the presence of a compact dense obscuring molecular gas in front of the nucleus of M51, which remains unresolved at our ∼1'' (∼34 pc) resolution, and consistent with the Seyfert 2 classification picture.

  8. A VLA gravitational lens survey

    NASA Technical Reports Server (NTRS)

    Hewitt, J. N.; Turner, E. L.; Burke, B. F.; Lawrence, C. R.; Bennett, C. L.

    1987-01-01

    A VLA survey designed to detect gravitational lensing on sub-arc second and arc second scales is described, and preliminary results of radio data are presented. In particular, it is found that the density of matter in the form of a uniform comoving number density of 10 to the 11th - 10 to the 12th solar mass compact objects, luminous or dark, must be substantially less than the critical density. Data obtained for the radio source 1042+178 are briefly examined.

  9. Gravitational lensing of active galactic nuclei.

    PubMed Central

    Hewitt, J N

    1995-01-01

    Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes. PMID:11607613

  10. Methodological Gravitism

    ERIC Educational Resources Information Center

    Zaman, Muhammad

    2011-01-01

    In this paper the author presents the case of the exchange marriage system to delineate a model of methodological gravitism. Such a model is not a deviation from or alteration to the existing qualitative research approaches. I have adopted culturally specific methodology to investigate spouse selection in line with the Grounded Theory Method. This…

  11. Gravitational Lensing

    ScienceCinema

    Lincoln, Don

    2016-07-12

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  12. Gravitational Lensing

    SciTech Connect

    Lincoln, Don

    2015-06-24

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  13. The proposal for new space-based gravitational experiments

    NASA Astrophysics Data System (ADS)

    Milyukov, Vadim; Sazhin, Mikhail; Zharov, Vladimir

    The development of space technologies opens new perspectives in solving the fundamental problems of gravity. We propose the experimental investigation of General Relativity (GR) in space experiments in following: a) measurement of post-Newtonian parameters (PPN), b) gravity wave detection in the low frequency band. The accuracy, with which GR is currently confirmed, is fractions of percent: 2.3× 10(-5) . However, in spite of the remarkable success of GR in the weak-field approximation, there are many reasons to consider alternative relativistic theories of gravity that predict the existence of effects other than GR, thus motivating new fundamental gravitational experiments. In this connection, the experimental measurements of PPN of parameters play a special role. To improve the accuracy of measurement of geodetic effects in the gravitational field of the Earth the clusters of spacecrafts, connected by microwave radio links and optical links, are widely used. Such a scheme allows to suppress effectively a coherent noise acting on the spacecraft, and to measure the distance between the satellites within a fraction of a millimeter. This technology was already tested for GRACE and GRAIL NASA missions. Furthermore, there are technologies allowing to effectively compensate non-gravitational noise to the level of 10(-10) - 10(-12) \\ m/s(2/sqrt{Hz}) . The project, which assume the lunch of cluster of the spacecrafts intended to study fundamental processes in the Universe, including the measurement of the PPN parameters and low frequency gravitational waves, is proposed in this report. We study the space-based systems in a configuration of few spacecrafts on different orbits in the gravitational field of the Earth for measuring these effects. Measurements of distances between spacecrafts are performed using microwave radio links, laser interferometry and ultra stable frequency standards. Developed modern technologies for distant measurements allow to reach the accuracy

  14. Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Saha, P.; Murdin, P.

    2000-11-01

    Gravity bends light rays in a way analogous to, but quantitatively different from, the way it bends trajectories of passing particles. If light from some bright object passes close enough to some foreground mass, that object's image will be altered. The effect is more like a piece of bathroom glass in the sky than a precision-ground and well-focused lens, but the terms `gravitational lensing' or ...

  15. Experimental gravitation

    NASA Astrophysics Data System (ADS)

    Lämmerzahl, Claus; di Virgilio, Angela

    2016-06-01

    100 years after the invention of General Relativity (GR) and 110 years after the development of Special Relativity (SR) we have to state that until now no single experiment or observation allows any doubt about the validity of these theories within the accuracy of the available data. Tests of GR can be divided into three categories: (i) test of the foundations of GR, (ii) tests of the consequences of GR, and (iii) test of the interplay between GR and quantum mechanics. In the first category, we have tests of the Einstein Equivalence Principle and the structure of the Newton axioms, in the second category we have effects like the gravitational redshift, light defection, gravitational time delay, the perihelion shift, the gravitomagnetic effects as the Lense-Thirring and Schiff effect, and gravitational waves. Tests of the effects of gravity on quantum systems are a first step towards experiments searching for a quantum gravity theory. In this paper, we also highlight practical applications in positioning, geodesy, and the International Atomic Time. After 100 years, GR can now definitely be regarded also as practical and applied science.

  16. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

  17. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy. PMID:16286284

  18. PKS 1830-211: A Possible Compound Gravitational Lens

    NASA Technical Reports Server (NTRS)

    Lovell, J. E. J.; Reynolds, J. E.; Jauncey, D. L.; Backus, P. R.; McCullock, P. M.; Sinclair, M. W.; Wilson, W. E.; Tzioumis, A. K.; Gough, R. G.; Ellingsen, S. P.; Phillips, C. J.; Preston, R. A.; Jones, D. L.

    1996-01-01

    Measurements of the properties of gravitational lenses have the power to tell us what sort of universe we live in. The brightest known radio Einstein ring/gravitational lens PKS 1830-211, whilst obscured by our Galaxy at optical wavelengths, has recently provided a lensing galaxy redshift of 0.89 through the detection of molecular absorption in the millimetre waveband.

  19. Parametric instabilities in weakly magnetized plasma

    SciTech Connect

    Weatherall, J.C.; Goldman, M.V.; Nicholson, D.R.

    1981-05-15

    Parametric instabilities in a weakly magnetized plasma are discussed. The results are applied to waves excited by electron streams which travel outward from the Sun along solar-wind magnetic field lines, as in a type III solar radio burst.

  20. Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Moniez, M.; Horne, K.; Street, R.

    2012-04-01

    Gravitational microlensing is a well established and unique field of time-domain astrophysics. For two decades microlensing surveys have been regularly observing millions of stars to detect elusive events that follow a characteristic Paczyński lightcurve. This workshop reviewed the current state of the field, and covered the major topics related to microlensing: searches for extrasolar planets, and studies of dark matter. There were also discussions of issues relating to the organisation of follow-up observations for microlensing, as well as serendipitous scientific outcomes resulting from extensive microlensing data.

  1. Radio Detection of Neutron Star Binary Mergers

    NASA Astrophysics Data System (ADS)

    Bear, Brandon; Cardena, Brett; Dispoto, Dana; Papadopoulos, Joanna; Kavic, Michael; Simonetti, John

    2011-10-01

    Neutron star binary systems lose energy through gravitational radiation, and eventually merge. The gravitational radiation from the merger can be detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). It is expected that a transient radio pulse will also be produced during the merger event. Detection of such radio transients would allow for LIGO to search for signals within constrained time periods. We calculate the LWA-1 detection rate of transient events from neutron star binary mergers. We calculate the detection rate of transient events from neutron star binary mergers for the Long Wavelength Array and the Eight-meter-wavelength Transient Array.

  2. Modified entropic gravitation in superconductors

    NASA Astrophysics Data System (ADS)

    de Matos, Clovis Jacinto

    2012-01-01

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

  3. Gravitational radiation from collapsing magnetized dust

    SciTech Connect

    Sotani, Hajime; Yoshida, Shijun; Kokkotas, Kostas D.

    2007-04-15

    In this article we study the influence of magnetic fields on the axial gravitational waves emitted during the collapse of a homogeneous dust sphere. We found that while the energy emitted depends weakly on the initial matter perturbations it has strong dependence on the strength and the distribution of the magnetic field perturbations. The gravitational wave output of such a collapse can be up to an order of magnitude larger or smaller calling for detailed numerical 3D studies of collapsing magnetized configurations.

  4. Optics in a nonlinear gravitational plane wave

    NASA Astrophysics Data System (ADS)

    Harte, Abraham I.

    2015-09-01

    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 in general relativity, allowing for arbitrarily-moving sources and observers in the presence of plane-symmetric gravitational waves. At least for freely falling sources and observers, it is shown that the commonly-used predictions of linear perturbation theory can be generically overshadowed by nonlinear effects; even for very weak gravitational waves, higher-order perturbative corrections involve secularly-growing terms which cannot necessarily be neglected when considering observations of sufficiently distant sources. 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.

  5. Newtorites in bar detectors of gravitational wave

    NASA Astrophysics Data System (ADS)

    Ronga, F.; ROG Collaboration

    2016-05-01

    The detection of particles with only gravitational interactions (Newtorites) in gravitational bar detectors was studied in 1984 by Bernard, De Rujula and Lautrup. The negative results of dark matter searches suggest to look to exotic possibilities like Newtorites. The limits obtained with the Nautilus bar detector will be presented and the possible improvements will be discussed. Since the gravitational coupling is very weak, the possible limits are very far from what is needed for dark matter, but for large masses are the best limits obtained on the Earth. An update of limits for MACRO particles will be given.

  6. EDITORIAL: Focus on Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Jain, Bhuvnesh

    2007-11-01

    Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

  7. Gravitational Waves and Time-Domain Astronomy

    NASA Astrophysics Data System (ADS)

    Centrella, Joan; Nissanke, Samaya; Williams, Roy

    2012-04-01

    The gravitational-wave window onto the universe will open in roughly five years, when Advanced LIGO and Virgo achieve the first detections of high-frequency gravitational waves, most likely coming from compact binary mergers. Electromagnetic follow-up of these triggers, using radio, optical, and high energy telescopes, promises exciting opportunities in multi-messenger time-domain astronomy. In the decade, space-based observations of low-frequency gravitational waves from massive black hole mergers, and their electromagnetic counterparts, will open up further vistas for discovery. This two-part workshop featured brief presentations and stimulating discussions on the challenges and opportunities presented by gravitational-wave astronomy. Highlights from the workshop, with the emphasis on strategies for electromagnetic follow-up, are presented in this report.

  8. Gravitational Waves and Time Domain Astronomy

    NASA Technical Reports Server (NTRS)

    Centrella, Joan; Nissanke, Samaya; Williams, Roy

    2012-01-01

    The gravitational wave window onto the universe will open in roughly five years, when Advanced LIGO and Virgo achieve the first detections of high frequency gravitational waves, most likely coming from compact binary mergers. Electromagnetic follow-up of these triggers, using radio, optical, and high energy telescopes, promises exciting opportunities in multi-messenger time domain astronomy. In the decade, space-based observations of low frequency gravitational waves from massive black hole mergers, and their electromagnetic counterparts, will open up further vistas for discovery. This two-part workshop featured brief presentations and stimulating discussions on the challenges and opportunities presented by gravitational wave astronomy. Highlights from the workshop, with the emphasis on strategies for electromagnetic follow-up, are presented in this report.

  9. Discovery of Misaligned Radio Emission in Galaxy Cluster Zw CL 2971

    NASA Astrophysics Data System (ADS)

    Wallack, Nicole; Migliore, C.; Resnick, A.; White, T.; Liu, C.

    2014-01-01

    In a search for green valley galaxies with radio loud active galactic nuclei (AGN), we found one such object that may be associated with the cluster of galaxies Zw CL 2971 (z = 0.098). Serendipitously, we found in this cluster a strong bent-jet radio source associated with the cluster's central dominant (cD) elliptical galaxy. The center of the cD galaxy is coincident (0.35 arcsecond) with the second brightest spot of radio continuum emission (34.3 mJy as measured by FIRST), but the brightest radio hotspot (66.8 mJy) is offset by 4.6 arcseconds 9 kpc at the redshift of the cluster) and has no visible counterpart. Furthermore, the optical spectrum of the cD galaxy has only weak emission lines, suggesting the absence of a currently active nucleus. It is possible that the counterpart is optically faint (possibly due to a recently completed duty cycle) or is not visible due to movement or position. If the radio source is a distant background object, then the brighter jet is most likely magnified by gravitational lensing. If the radio source is located at the redshift of the cluster, then the brighter radio jet trails backward toward and past the cD galaxy to a distance of ~120 kpc, while the fainter jet is bent at a nearly orthogonal angle, ~40 kpc away from the brightest radio hotspot, in the opposite direction. These geometric offsets could be used to constrain the duty cycle history of the AGN creating the radio emission, as well as the dynamical properties of the intracluster medium.

  10. Radio Journalism.

    ERIC Educational Resources Information Center

    Bittner, John R.; Bittner, Denise A.

    This book, a how-to-do-it guide for the novice and the professional alike, deals with several aspects of radio journalism: producing documentaries, preparing and announcing radio news, ethics and responsibility, regulation of radio journalism, and careers. It traces the history and growth of radio news, shows its impact on the public, and…

  11. Gravitational Lensing Extends SETI Range

    NASA Astrophysics Data System (ADS)

    Factor, Richard

    Microwave SETI (The Search for Extraterrestrial Intelligence) focuses on two primary strategies, the "Targeted Search" and the "All-Sky Survey." Although the goal of both strategies is the unequivocal discovery of a signal transmitted by intelligent species outside our solar system, they pursue the strategies in very different manners and have vastly different requirements. This chapter introduces Gravitational Lensing SETI (GL-SETI), a third strategy. Its goal is the unequivocal discovery of an extraterrestrial signal, with equipment and data processing requirements that are substantially different from the commonly-used strategies. This strategy is particularly suitable for use with smaller radio telescopes and has budgetary requirements suitable for individual researchers.

  12. Radio efficiency of pulsars

    SciTech Connect

    Szary, Andrzej; Melikidze, George I.; Gil, Janusz; Zhang, Bing; Xu, Ren-Xin E-mail: zhang@physics.unlv.edu

    2014-03-20

    We investigate radio emission efficiency, ξ, of pulsars and report a near-linear inverse correlation between ξ and the spin-down power, E-dot , as well as a near-linear correlation between ξ and pulsar age, τ. This is a consequence of very weak, if any, dependences of radio luminosity, L, on pulsar period, P, and the period derivative, P-dot , in contrast to X-ray or γ-ray emission luminosities. The analysis of radio fluxes suggests that these correlations are not due to a selection effect, but are intrinsic to the pulsar radio emission physics. We have found that, although with a large variance, the radio luminosity of pulsars is ≈10{sup 29} erg s{sup –1}, regardless of the position in the P-- P-dot diagram. Within such a picture, a model-independent statement can be made that the death line of radio pulsars corresponds to an upper limit in the efficiency of radio emission. If we introduce the maximum value for radio efficiency into the Monte Carlo-based population syntheses we can reproduce the observed sample using the random luminosity model. Using the Kolmogorov-Smirnov test on a synthetic flux distribution reveals a high probability of reproducing the observed distribution. Our results suggest that the plasma responsible for generating radio emission is produced under similar conditions regardless of pulsar age, dipolar magnetic field strength, and spin-down rate. The magnetic fields near the pulsar surface are likely dominated by crust-anchored, magnetic anomalies, which do not significantly differ among pulsars, leading to similar conditions for generating electron-positron pairs necessary to power radio emission.

  13. Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1957-06-01

    Experimental results on the non-conservation of parity and charge conservation in weak interactions are reviewed. The two-component theory of the neutrino is discussed. Lepton reactions are examined under the assumption of the law of conservation of leptons and that the neutrino is described by a two- component theory. From the results of this examination, the universal Fermi interactions are analyzed. Although reactions involving the neutrino can be described, the same is not true of reactions which do not involve the lepton, as the discussion of the decay of K mesons and hyperons shows. The question of the invariance of time reversal is next examined. (J.S.R.)

  14. The importance of Radio Quiet Zone (RQZ) for radio astronomy

    NASA Astrophysics Data System (ADS)

    Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin

    2013-05-01

    Most of radio observatories are located in isolated areas. Since radio sources from the universe is very weak, astronomer need to avoid radio frequency interference (RFI) from active spectrum users and radio noise produced by human made (telecommunication, mobile phone, microwave user and many more. There are many observatories around the world are surrounded by a Radio Quiet Zone (RQZ), which is it was set up using public or state laws. A Radio Quiet Zone normally consists of two areas: an exclusive area in which totally radio emissions are forbidden, with restrictions for residents and business developments, and a larger (radius up to 100 km above) coordination area where the power of radio transmission limits to threshold levels. Geographical Information System (GIS) can be used as a powerful tool in mapping large areas with varying RQZ profiles. In this paper, we report the initial testing of the usage of this system in order to identify the areas were suitable for Radio Quiet Zone. Among the important parameters used to develop the database for our GIS are population density, information on TV and telecommunication (mobile phones) transmitters, road networks (highway), and contour shielding. We will also use other information gathered from on-site RFI level measurements on selected 'best' areas generated by the GIS. The intention is to find the best site for the purpose of establishing first radio quiet zones for radio telescope in Malaysia.

  15. The Nuclear Electromagnetic Graviton, Basis of Gravity-Gravitation and Nuclear Quantum Gravitation

    NASA Astrophysics Data System (ADS)

    Kotas, Ronald

    2003-04-01

    The basic attraction of two nuclei at an average .8546Angstroms apart, and the dynamic Electromagnetic factor included in the Newtonian formula equals Gq = 1.010334x10-48 Newtons. This is the basic Graviton function. This ALTERNATING ELECTROMAGNETIC DYNAMIC FORCE couples between the nuclei in masses according to the type of mass, the number of nuclei, and through the mass that produces a gravitating body. Nuclei linearly and dynamically couple in gravitating mass to produce maximum Gravity at the surface. Nucleon polar Electromagnetic build-up is what causes Gravity on a Gravitating Body. The Electromagnetic Graviton also propagates through space and produces Gravitation between Gravitating masses. Electromagnetic Graviton energy has to have a wavelength approximately the size of one nuclei, 2.98x10-15 meters and a frequency of 1.007 x10-23 Hertz. There are many proofs that Gravity and Gravitation are Electromagnetic. Clearly, there is ONE FORCE that acts at a distance in many ways. It is very apparent that this ONE FORCE is ELECTROMAGNETISM. This is the cause of the nuclear strong force, the nuclear weak force, Gravity and Gravitation. Gravity and Gravitation are Electromagnetic - NUCLEAR QUANTUM GRAVITATION. See: http://www.physicaloverviews.org

  16. Gravitational lensing in plasmic medium

    SciTech Connect

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

    2015-07-15

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  17. Gravitational lensing in plasmic medium

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  18. Gravitational Lensing: Einstein's unfinished symphony

    NASA Astrophysics Data System (ADS)

    Treu, Tommaso; Ellis, Richard S.

    2015-01-01

    Gravitational lensing - the deflection of light rays by gravitating matter - has become a major tool in the armoury of the modern cosmologist. Proposed nearly a hundred years ago as a key feature of Einstein's theory of general relativity, we trace the historical development since its verification at a solar eclipse in 1919. Einstein was apparently cautious about its practical utility and the subject lay dormant observationally for nearly 60 years. Nonetheless there has been rapid progress over the past twenty years. The technique allows astronomers to chart the distribution of dark matter on large and small scales thereby testing predictions of the standard cosmological model which assumes dark matter comprises a massive weakly-interacting particle. By measuring the distances and tracing the growth of dark matter structure over cosmic time, gravitational lensing also holds great promise in determining whether the dark energy, postulated to explain the accelerated cosmic expansion, is a vacuum energy density or a failure of general relativity on large scales. We illustrate the wide range of applications which harness the power of gravitational lensing, from searches for the earliest galaxies magnified by massive clusters to those for extrasolar planets which temporarily brighten a background star. We summarise the future prospects with dedicated ground and space-based facilities designed to exploit this remarkable physical phenomenon.

  19. Doppler-cancelled response to VLF gravitational waves

    NASA Technical Reports Server (NTRS)

    Caporali, A.

    1981-01-01

    The interaction of long periodic gravitational waves with a three link microwave system known as the Doppler Cancelling System is discussed. This system, which was developed for a gravitational redshift experiment, uses one-way and two-way Doppler informatin to construct the beat signal of two reference oscillators moving with respect to each other. The geometric optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational wave space-time. The signature left on the Doppler-cancelled beat by burst and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler Cancelling System and that of a Doppler tracking system which employs two-way, round-trip radio waves. A three-fold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.

  20. Gravitational lens time delays and gravitational waves

    SciTech Connect

    Frieman, J.A. Department of Astronomy Astrophysics, University of Chicago, Chicago, Illinois 60637 ); Harari, D.D.; Surpi, G.C. )

    1994-10-15

    Using Fermat's principle, we analyze the effects of very long wavelength gravitational waves upon the images of a gravitationally lensed quasar. We show that the lens equation in the presence of gravity waves is equivalent to that of a lens with a different alignment between source, deflector, and observer in the absence of gravity waves. Contrary to a recent claim, we conclude that measurements of time delays in gravitational lenses cannot serve as a method to detect or constrain a stochastic background of gravitational waves of cosmological wavelengths, because the wave-induced time delay is observationally indistinguishable from an intrinsic time delay due to the lens geometry.

  1. Approximation methods in gravitational-radiation theory

    NASA Technical Reports Server (NTRS)

    Will, C. M.

    1986-01-01

    The observation of gravitational-radiation damping in the binary pulsar PSR 1913 + 16 and the ongoing experimental search for gravitational waves of extraterrestrial origin have made the theory of gravitational radiation an active branch of classical general relativity. In calculations of gravitational radiation, approximation methods play a crucial role. Recent developments are summarized in two areas in which approximations are important: (a) the quadrupole approxiamtion, which determines the energy flux and the radiation reaction forces in weak-field, slow-motion, source-within-the-near-zone systems such as the binary pulsar; and (b) the normal modes of oscillation of black holes, where the Wentzel-Kramers-Brillouin approximation gives accurate estimates of the complex frequencies of the modes.

  2. High stability radio links

    NASA Technical Reports Server (NTRS)

    Kursinski, E. Robert

    1989-01-01

    Radio telecommunication links are used for communication with deep space probes. These links consist of sinusoidal carrier signals at radio frequencies (RF) modulated with information sent between the spacecraft and the earth. This carrier signal is a very pure and stable sinusoid, typically derived from an atomic frequency standard whose frequency and phase are used to measure the radial velocity of the probe and from this and other data types derive its trajectory. This same observable can be used to search for space-time distortions cased by low frequency (0.1 to 100 MHz) gravitation radiation. How such a system works, what its sensitivity limitations are, and what potential future improvements can be made are discussed.

  3. Radio astronomy - The next decade

    SciTech Connect

    Kellermann, K.I. )

    1991-09-01

    Discoveries made over the past several decades by radio astronomers include radio galaxies, quasars, pulsars, gravitational lenses, energetic bursts from the sun and Jupiter, the greenhouse effect on Venus, the rotation of Mercury, giant molecular clouds, violent activity in galactic nuclei, and cosmic background radiation. This paper discusses the development of ever more powerful radio telescopes, which include the VLA operated by NRAO near Socorro (New Mexico); the new NRAO's 100-m Green Bank Telescope being constructed in Green Bank (West Virginia); and the proposed Millimeter Array, which will consist of 40 antennas, each 8-m across, arranged in any of four different ways depending on the size of the region under study. Consideration is also given to methods for increasing the resolving power and image quality of radio telescopes, with special attention given to very-long-baseline interferometry.

  4. Gravitation in Material Media

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2011-01-01

    When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium…

  5. The Deep Space Network as an instrument for radio science research

    NASA Technical Reports Server (NTRS)

    Asmar, S. W.; Renzetti, N. A.

    1993-01-01

    Radio science experiments use radio links between spacecraft and sensor instrumentation that is implemented in the Deep Space Network. The deep space communication complexes along with the telecommunications subsystem on board the spacecraft constitute the major elements of the radio science instrumentation. Investigators examine small changes in the phase and/or amplitude of the radio signal propagating from a spacecraft to study the atmospheric and ionospheric structure of planets and satellites, planetary gravitational fields, shapes, masses, planetary rings, ephemerides of planets, solar corona, magnetic fields, cometary comae, and such aspects of the theory of general relativity as gravitational waves and gravitational redshift.

  6. Exploring the Dynamic Radio Sky

    NASA Astrophysics Data System (ADS)

    Mooley, Kunal P.; Hallinan, Gregg; Frail, Dale A.; Myers, Steven T.; Kulkarni, Shrinivas R.; Bourke, Stephen; Horesh, Assaf

    2015-01-01

    Most of what is currently known about slow radio transients (supernovae, gamma-ray bursts, tidal disruption events, stellar flares, etc.) has come via radio follow-up of objects identified by synoptic telescopes at optical, X-ray or gamma-ray wavelengths. However, with the ability to capture obscured, unbeamed and magnetically-driven phenomena, radio surveys offer unique discovery strong diagnostic for cosmic transients. For the first time, we are systematically exploring the dynamic radio sky on timescales between one day to several years using multi-epoch large surveys with the Karl G. Jansky Array (VLA). We have carried out surveys in the COSMOS deep field as well as wide fields like Stripe 82. I have developed a unique infrastructure for near-real-time calibration, imaging, transient search, transient vetting, rapid multiwavelength follow-up, and contemporaneous optical surveys to better characterize radio transient phenomena. A large part of my thesis includes the commissioning of a new observing mode at the VLA: On-The-Fly Mosaicking. This mode has significantly improved the survey efficiency of the VLA, and it is a driver for VLASS, the future all-sky survey planned with this telescope. Through our radio surveys we have discovered several fascinating transients that are unique to the radio. These surveys have established the VLA as an efficient transient discovery machine. My thesis has enormous implications for how to design efficient transient surveys for the next generation of radio interferometer facilities like ASKAP, MeerKAT, WSRT/Apertif and LOFAR. My work has also provided answers to key problems such as the rates of transients, demographics of variability of radio sources including AGN, and false-positive foreground for future searches for the radio counterparts of gravitational-wave (GW) sources.

  7. Optimizing SNAP for Weak Lensing

    NASA Astrophysics Data System (ADS)

    High, F. W.; Ellis, R. S.; Massey, R. J.; Rhodes, J. D.; Lamoureux, J. I.; SNAP Collaboration

    2004-12-01

    The Supernova/Acceleration Probe (SNAP) satellite proposes to measure weak gravitational lensing in addition to type Ia supernovae. Its pixel scale has been set to 0.10 arcsec per pixel as established by the needs of supernova observations. To find the optimal pixel scale for accurate weak lensing measurements we conduct a tradeoff study in which, via simulations, we fix the suvey size in total pixels and vary the pixel scale. Our preliminary results show that with a smaller scale of about 0.08 arcsec per pixel we can minimize the contribution of intrinsic shear variance to the error on the power spectrum of mass density distortion. Currently we are testing the robustness of this figure as well as determining whether dithering yields analogous results.

  8. Gravitational radiation and the ultimate speed in Rosen's bimetric theory of gravity

    NASA Technical Reports Server (NTRS)

    Caves, C. M.

    1980-01-01

    In Rosen's bimetric theory of gravity the (local) speed of gravitational radiation is determined by the combined effects of cosmological boundary values and nearby concentrations of matter. It is possible for the speed of gravitational radiation to be less than the speed of light. It is here shown that the emission of gravitational radiation prevents particles of nonzero rest mass from exceeding the speed of gravitational radiation. Observations of relativistic particles place limits on the speed of gravitational radiation and the cosmological boundary values today, and observations of synchroton radiation from compact radio sources place limits on the cosmological boundary values in the past.

  9. Experimental investigations of weak definite and weak indefinite noun phrases

    PubMed Central

    Klein, Natalie M.; Gegg-Harrison, Whitney M.; Carlson, Greg N.; Tanenhaus, Michael K.

    2013-01-01

    Definite noun phrases typically refer to entities that are uniquely identifiable in the speaker and addressee’s common ground. Some definite noun phrases (e.g. the hospital in Mary had to go the hospital and John did too) seem to violate this uniqueness constraint. We report six experiments that were motivated by the hypothesis that these “weak definite” interpretations arise in “incorporated” constructions. Experiments 1-3 compared nouns that seem to allow for a weak definite interpretation (e.g. hospital, bank, bus, radio) with those that do not (e.g. farm, concert, car, book). Experiments 1 and 2 used an instruction-following task and picture-judgment task, respectively, to demonstrate that a weak definite need not uniquely refer. In Experiment 3 participants imagined scenarios described by sentences such as The Federal Express driver had to go to the hospital/farm. The imagined scenarios following weak definite noun phrases were more likely to include conventional activities associated with the object, whereas following regular nouns, participants were more likely to imagine scenarios that included typical activities associated with the subject; similar effects were observed with weak indefinites. Experiment 4 found that object-related activities were reduced when the same subject and object were used with a verb that does not license weak definite interpretations. In Experiment 5, a science fiction story introduced an artificial lexicon for novel concepts. Novel nouns that shared conceptual properties with English weak definite nouns were more likely to allow weak reference in a judgment task. Experiment 6 demonstrated that familiarity for definite articles and anti- familiarity for indefinite articles applies to the activity associated with the noun, consistent with predictions made by the incorporation analysis. PMID:23685208

  10. Weathering the Largest Storms in the Universe : Understanding environmental effects on extended radio emission in clusters

    NASA Astrophysics Data System (ADS)

    Dehghan, S.

    2014-05-01

    This thesis presents an investigation of the habitat of extended radio sources, and the way in which the generation and properties of these radio sources are affected by environmental factors. We begin with a detailed structure analysis of the 0.3 deg2 area of the MUSYC-ACES field, generated by applying a density-based clustering method, known as DBSCAN, to our spectroscopic and photometric samples of the field. As a result, we identify 62 over-dense regions across the field. Based on the properties of the detected structures, we classify 13 as clusters, of which 90% are associated with diffuse soft-band X-ray emission. This provides a strong and independent confirmation that both the clustering and classification methodologies are reliable for use in investigation of the environment of the radio sources in the Chandra Deep Field South (CDFS). Using an interpolation-based method followed by a new calibration technique of using clusters of similar mass as standard candles, we are able to estimate the local environmental richness for a desired region. This methodology is applied to a sample of AGNs and star forming galaxies in the CDFS to probe whether or not the radio luminosity of the different radio sources is correlated to their environments. As a result, we do not find a significant correlation between the radio luminosity and the environment of star-forming galaxies and radio-quiet AGNs, however, a weak positive dependency is spotted for radio-loud AGNs. This may indicate that over-populated environments trigger or enhance the radio activity processes in the AGNs. We find that star-forming galaxies, unlike radio-loud AGNs, tend to avoid overpopulated environments especially at low redshifts. However, radio-loud AGN are found in both poor and rich environments. As a result, we find neither of these radio sources suitable for tracing the over-dense regions of the Universe, unlike tailed radio galaxies. It is believed that tailed radio galaxies reside in the dense

  11. Gravitational wave astrophysics with compact binary systems

    NASA Astrophysics Data System (ADS)

    Addison, Eric

    2014-10-01

    Gravitational waves are ripples in the fabric of spacetime that convey information about changing gravitational fields. Large-scale detection projects are currently in operation, and more advanced detectors are being designed and built. Though we have yet to make a direct detection of a gravitational wave signal, upgrades to current detectors are expected to bring the first detections within the next year or two. Gravitational waves will bring us information about astrophysical phenomena that is complementary to the information gained from photon-based observations (e.g., telescopes and radio receivers). One of the primary sources of gravitational waves are binary systems: two massive objects that orbit around each other due to their mutual gravitational attraction. These systems can have very predictable gravitational wave signatures due to their repetitive motions, making them ideal gravitational wave sources. In this dissertation, I present two research projects pertaining to gravitational wave astrophysics and compact binary systems. In the first, I explore interactions between compact binary systems near the center of our galaxy with the supermassive black hole that resides there. I am interested in the final state of the binary as a result of the interaction, ranging from small perturbations to the orbit up to total disruption. In the case of disruption, I characterize the new orbits formed between the binary components and the central black hole, known as extreme mass ratio inspirals. For binaries that survive the encounter, I examine the changes they experience, and find on average, they will merge together as a result of gravitational wave emission faster than before the encounter. In the second project, I propose a new method of measuring the radius of the swirling disc of gas and dust that encircles some stars in compact binary systems, known as the accretion disc. This method relies on the use of coupled electromagnetic and gravitational wave

  12. Gravitational Wave Propulsion

    NASA Astrophysics Data System (ADS)

    Fontana, Giorgio

    2005-02-01

    There is only one experimental proof that gravitational waves exist. With such a limitation, it may seem premature to suggest the possibility that gravitational waves can became a preferred space propulsion technique. The present understanding of the problem indicates that this is not the case. The emission of gravitational waves from astrophysical sources has been confirmed by observation, the respective detection at large distance from the source is difficult and actually we have no confirmation of a successful detection. Therefore the required preliminary discovery has been already made. This opinion is enforced by many different proposals for building the required powerful gravitational wave generators that have recently appeared in the literature and discussed at conferences. It is no longer reasonable to wait for additional confirmation of the existence of gravitational waves to start a program for building generators and testing their possible application to space travel. A vast literature shows that gravitational waves can be employed for space propulsion. Gravitational wave rockets have been proposed, non-linearity of Einstein equations allows the conversion of gravitational waves to a static gravitational field and ``artificial gravity assist'' may become a new way of travelling in space-time. Different approaches to gravitational wave propulsion are reviewed and compared. Gravitational wave propulsion is also compared to traditional rocket propulsion and an undeniable advantage can be demonstrated in terms of efficiency and performance. Testing the predictions will require gravitational wave generators with high power and wavelength short enough for producing high energy densities. Detectors designed for the specific application must be developed, taking into account that non-linearity effects are expected. The study and development of Gravitational wave propulsion is a very challenging endeavor, involving the most complex theories, sophisticated

  13. Radio wave.

    PubMed

    Elkin, V

    1992-01-01

    In developing countries with high rates of poverty and illiteracy, radio is emerging as an excellent medium for delivering information on health issues, family planning, nutrition, and agricultural development. Since radio does not require wired electricity, it can reach remote rural populations. Surveys have found that between 50-75% of poor rural households in developing countries own radios, and the majority listen to educational radio at least once a week. A program that reaches the urban poor outside of Lima, Peru, has been instrumental in controlling the spread of cholera. A Bolivian station broadcasts 8 hours of literacy, health, agricultural, and cultural programming a day to an audience of more than 2 million Aymara Indians. Small village radio stations with a broadcast range of 15 miles can be established for under US$400 and can generally achieve sustainability through local fundraising events such as raffles. In many cases, listeners have become broadcasters at their local radio stations.

  14. Unify the electromagnetic force and gravitation

    NASA Astrophysics Data System (ADS)

    Sheng Ming, Zheng

    2013-04-01

    In the process of mankind investigate natural rule: people know four kinds of force: electromagnetic force, gravitation, weak force, and strong force. Meanwhile people use these four kinds force to explain all phenomena in the Nature. Obviously people do not know their mechanism of origin until now. On the other hand, these four kinds force is the difference showing form of one force, is not it? For solve these questions and find their mechanism of origin, I do some experiments and discover that the moving photons produce gravitation. This discovery shows the origin of gravitation. Meanwhile I also do experiments show that light is a particle, but is not a wave-particle duality. My experiments show that the elementary particles moving produce gravitation and electromagnetic force, this effect also produce wave effect. That is to say my experiment and calculate not only reveal the origin of gravitation, but also reveal the origin of electric charge and magnetic force. Base on this I first unify the electromagnetic force and gravitation. The more detail see below website: https://www.lap-publishing.com/catalog/details/store/gb/book/978-3-8473-2658-8/mechanism-of-interaction-in-moving-matter.

  15. Unify the electromagnetic force and gravitation

    NASA Astrophysics Data System (ADS)

    Ming, Zheng Sheng

    2013-04-01

    In the process of mankind investigate natural rule: people know four kinds of force: electromagnetic force, gravitation, weak force, and strong force. Meanwhile people use these four kinds force to explain all phenomena in the Nature. Obviously people do not know their mechanism of origin until now. On the other hand, these four kinds force is the difference showing form of one force, is not it? For solve these questions and find their mechanism of origin, I do some experiments and discover that the moving photons produce gravitation. This discovery shows the origin of gravitation. Meanwhile I also do experiments show that light is a particle, but is not a wave-particle duality. My experiments show that the elementary particles moving produce gravitation and electromagnetic force, this effect also produce wave effect. That is to say my experiment and calculate not only reveal the origin of gravitation, but also reveal the origin of electric charge and magnetic force. Base on this I first unify the electromagnetic force and gravitation. The more detail see below website: https://www.lap-publishing.com/catalog/details/store/gb/book/978-3-8473-2658-8/mechanism-of-interaction-in-moving-matter

  16. Radio sociology

    NASA Astrophysics Data System (ADS)

    Swenson, George W., Jr.

    1996-04-01

    A work was conducted, using radio telemetry, to locate a migrating, radio-tagged, sharp-shinned hawk. The hawk was monitored through the noise radiation it created. The hawk was found. During this study, it was found that the concentration of population corresponds with areas of increased noise temperature. Through this study, a bigger study was planned. The study would involved the relationship between a place's radiation signature and its other attributes, such as economic type, population, geographic concentration. The method of radio sociology would be used to track the sources of radio noise.

  17. Weak lensing and cosmological investigation

    NASA Astrophysics Data System (ADS)

    Acquaviva, Viviana

    2005-03-01

    In the last few years the scientific community has been dealing with the challenging issue of identifying the dark energy component. We regard weak gravitational lensing as a brand new, and extremely important, tool for cosmological investigation in this field. In fact, the features imprinted on the Cosmic Microwave Background radiation by the lensing from the intervening distribution of matter represent a pretty unbiased estimator, and can thus be used for putting constraints on different dark energy models. This is true in particular for the magnetic-type B-modes of CMB polarization, whose unlensed spectrum at large multipoles (l ~= 1000) is very small even in presence of an amount of gravitational waves as large as currently allowed by the experiments: therefore, on these scales the lensing phenomenon is the only responsible for the observed power, and this signal turns out to be a faithful tracer of the dark energy dynamics. We first recall the formal apparatus of the weak lensing in extended theories of gravity, introducing the physical observables suitable to cast the bridge between lensing and cosmology, and then evaluate the amplitude of the expected effect in the particular case of a Non-Minimally-Coupled model, featuring a quadratic coupling between quintessence and Ricci scalar.

  18. Gravitational waves from inflation

    NASA Astrophysics Data System (ADS)

    Guzzetti, M. C.; Bartolo, N.; Liguori, M.; Matarrese, S.

    2016-09-01

    The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index nT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.

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

    SciTech Connect

    Seto, Naoki

    2009-11-15

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

  20. Galactic Internet made possible by star gravitational lensing

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2013-02-01

    In this paper we study how to create a radio bridge between the Sun and any other star made up by both the gravitational lenses of the Sun and that star. The alignment for this radio bridge to work is very strict, but the power-saving is enormous, due to the huge contributions of the two stars' lenses to the overall antenna gain of the system. In particular, we study in detail: The Sun-Alpha Centauri A radio bridge. The Sun-Barnard's star radio bridge. The Sun-Sirius A radio bridge. The radio bridge between the Sun and any Sun-like star located in the Galactic Bulge. The radio bridge between the Sun and a similar Sun-like star located inside the Andromeda galaxy (M31). Finally, we find the information channel capacity for each of the above radio bridges, putting thus a physical constraint to the maximum information transfer that will be enabled even by exploiting the stars as gravitational lenses. The conclusion is that a Galactic Internet is indeed physically possible. May be the Galactic Internet already is in existence, and was created long ago by civilizations more advanced than ours. But the potential for creating such a system has only recently been realized by Humans.

  1. College Radio.

    ERIC Educational Resources Information Center

    Sauls, Samuel J.

    As with commercial stations, the underlying premise of the college radio station is to serve the community, whether it be the campus community or the community at large, but in unique ways often geared to underserved niches of the population. Much of college radio's charm lies in its unpredictable nature and constant mutations. The stations give…

  2. Radio Astronomy

    NASA Technical Reports Server (NTRS)

    Shaffer, R. D.; Wolken, P. R.; Niell, A. E.

    1981-01-01

    The activities of the DSN in support of Radio and Radar Astronomy Operations during September through December 1980 are described. Emphasis is on a report of an experiment selected for use of the DSN by the radio Astronomy Experiment Selection Panel: that of VLBI observations of the energetic galactic object SS-433.

  3. Radio astronomy

    NASA Technical Reports Server (NTRS)

    Wolken, P. R.; Schaffer, R. D.; Gorenstein, M. V.

    1981-01-01

    The activities of the Deep Space Network in support of Radio Astronomy Operations during April and May 1981 are reported. Work in progres in support of an experiment selected for use of the DSN by the Radio Astronomy Experiment Selection Panel, Twin Quasi-Stellar Object VLBI, is reported.

  4. Radio astronomy

    NASA Technical Reports Server (NTRS)

    Shaffer, R. D.; Wolken, P. R.; Gulkis, S.

    1981-01-01

    The activities of the Deep Space Network in support of radio astronomy operations during the first quarter of 1981 are reported. Results of the use of a low noise maser are presented, as well as updates in DSN support of experiments sanctioned by the Radio Astronomy Experiment Selection Panel.

  5. Radio astronomy

    NASA Technical Reports Server (NTRS)

    Taylor, R. M.; Manchester, R. N.

    1980-01-01

    The activities of the Deep Space Network in support of radio and radar astronomy operations during July and August 1980 are reported. A brief update on the OSS-sponsored planetary radio astronomy experiment is provided. Also included are two updates, one each from Spain and Australia on current host country activities.

  6. Gravitation in material media

    NASA Astrophysics Data System (ADS)

    Ridgely, Charles T.

    2011-03-01

    When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium is herein derived on the basis of classical, Newtonian gravitational theory and by a general relativistic use of Archimedes' principle. It is envisioned that the techniques presented herein will be most useful to graduate students and those undergraduate students having prior experience with vector analysis and potential theory.

  7. WEAK LENSING MASS RECONSTRUCTION: FLEXION VERSUS SHEAR

    SciTech Connect

    Pires, S.

    2010-11-10

    Weak gravitational lensing has proven to be a powerful tool to map directly the distribution of dark matter in the universe. The technique, currently used, relies on the accurate measurement of the gravitational shear that corresponds to the first-order distortion of the background galaxy images. More recently, a new technique has been introduced that relies on the accurate measurement of the gravitational flexion that corresponds to the second-order distortion of the background galaxy images. This technique should probe structures on smaller scales than that of shear analysis. The goal of this paper is to compare the ability of shear and flexion to reconstruct the dark matter distribution by taking into account the dispersion in shear and flexion measurements. Our results show that the flexion is less sensitive than shear for constructing the convergence maps on scales that are physically feasible for mapping, meaning that flexion alone should not be used to do convergence map reconstruction, even on small scales.

  8. Vacuum entanglement enhancement by a weak gravitational field

    SciTech Connect

    Cliche, M.; Kempf, A.

    2011-02-15

    Separate regions in space are generally entangled, even in the vacuum state. It is known that this entanglement can be swapped to separated Unruh-DeWitt detectors, i.e., that the vacuum can serve as a source of entanglement. Here, we demonstrate that, in the presence of curvature, the amount of entanglement that Unruh-DeWitt detectors can extract from the vacuum can be increased.

  9. MAPPING THE DARK MATTER WITH POLARIZED RADIO SURVEYS

    SciTech Connect

    Brown, Michael L.; Battye, Richard A.

    2011-07-01

    In a recent paper, we proposed the use of integrated polarization measurements of background galaxies in radio weak gravitational lensing surveys and investigated the potential impact on the statistical measurement of cosmic shear. Here we extend this idea to reconstruct maps of the projected dark matter distribution or lensing convergence field. The addition of polarization can, in principle, greatly reduce shape noise due to the intrinsic dispersion in galaxy ellipticities. We show that maps reconstructed using this technique in the radio band can be competitive with those derived using standard lensing techniques which make use of many more galaxies. In addition, since the reconstruction noise is uncorrelated between these standard techniques and the polarization technique, their comparison can serve as a powerful check for systematics and their combination can reduce noise further. We examine the convergence reconstruction which could be achieved with two forthcoming facilities: (1) a deep survey, covering 1.75 deg{sup 2} using the e-MERLIN instrument currently being commissioned in the UK and (2) the high-resolution, deep wide-field surveys which will eventually be conducted with the Square Kilometre Array.

  10. Radio Telescopes

    NASA Astrophysics Data System (ADS)

    Ekers, Ron; Wilson, Thomas L.

    ``Radio Telescopes" starts with a brief historical introduction from Jansky's1931 discovery of radio emission from the Milky Way through the development ofradio telescope dishes and arrays to aperture synthesis imaging. It includessufficient basics of electromagnetic radiation to provide some understanding of thedesign and operation of radio telescopes. The criteria such as frequencyrange, sensitivity, survey speed, angular resolution, and field of view thatdetermine the design of radio telescopes are introduced. Because it is soeasy to manipulate the electromagnetic waves at radio frequencies, radiotelescopes have evolved into many different forms, sometimes with "wire"structures tuned to specific wavelengths, which look very different from anykind of classical telescope. To assist astronomers more familiar with otherwavelength domains, the appendix A.1. includes a comparison of radioand optical terminology. Some of the different types of radio telescopesincluding the filled aperture dishes, electronically steered phased arrays, andaperture synthesis radio telescopes are discussed, and there is a sectioncomparing the differences between dishes and arrays. Some of the morerecent developments including hierarchical beam forming, phased arrayfeeds, mosaicing, rotation measure synthesis, digital receivers, and longbaseline interferometers are included. The problem of increasing radiofrequency interference is discussed, and some possible mitigation strategies areoutlined.

  11. Multibaseline gravitational wave radiometry

    SciTech Connect

    Talukder, Dipongkar; Bose, Sukanta; Mitra, Sanjit

    2011-03-15

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

  12. Investigations of Galaxy Clusters Using Gravitational Lensing

    SciTech Connect

    Wiesner, Matthew P.

    2014-08-01

    In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

  13. Gravitationally coupled electroweak monopole

    NASA Astrophysics Data System (ADS)

    Cho, Y. M.; Kimm, Kyoungtae; Yoon, J. H.

    2016-10-01

    We present a family of gravitationally coupled electroweak monopole solutions in Einstein-Weinberg-Salam theory. Our result confirms the existence of globally regular gravitating electroweak monopole which changes to the magnetically charged black hole as the Higgs vacuum value approaches to the Planck scale. Moreover, our solutions could provide a more accurate description of the monopole stars and magnetically charged black holes.

  14. Advanced Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    Blair, D. G.; Howell, E. J.; Ju, L.; Zhao, C.

    2012-02-01

    Part I. An Introduction to Gravitational Wave Astronomy and Detectors: 1. Gravitational waves D. G. Blair, L. Ju, C. Zhao and E. J. Howell; 2. Sources of gravitational waves D. G. Blair and E. J. Howell; 3. Gravitational wave detectors D. G. Blair, L. Ju, C. Zhao, H. Miao, E. J. Howell, and P. Barriga; 4. Gravitational wave data analysis B. S. Sathyaprakash and B. F. Schutz; 5. Network analysis L. Wen and B. F. Schutz; Part II. Current Laser Interferometer Detectors: Three Case Studies: 6. The Laser Interferometer Gravitational-Wave Observatory P. Fritschel; 7. The VIRGO detector S. Braccini; 8. GEO 600 H. Lück and H. Grote; Part III. Technology for Advanced Gravitational Wave Detectors: 9. Lasers for high optical power interferometers B. Willke and M. Frede; 10. Thermal noise, suspensions and test masses L. Ju, G. Harry and B. Lee; 11. Vibration isolation: Part 1. Seismic isolation for advanced LIGO B. Lantz; Part 2. Passive isolation J-C. Dumas; 12. Interferometer sensing and control P. Barriga; 13. Stabilizing interferometers against high optical power effects C. Zhao, L. Ju, S. Gras and D. G. Blair; Part IV. Technology for Third Generation Gravitational Wave Detectors: 14. Cryogenic interferometers J. Degallaix; 15. Quantum theory of laser-interferometer GW detectors H. Miao and Y. Chen; 16. ET. A third generation observatory M. Punturo and H. Lück; Index.

  15. Those Elusive Gravitational Waves

    ERIC Educational Resources Information Center

    MOSAIC, 1976

    1976-01-01

    The presence of gravitational waves was predicted by Einstein in his theory of General Relativity. Since then, scientists have been attempting to develop a detector sensitive enough to measure these cosmic signals. Once the presence of gravitational waves is confirmed, scientists can directly study star interiors, galaxy cores, or quasars. (MA)

  16. Measuring neutrino masses with weak lensing

    SciTech Connect

    Wong, Yvonne Y. Y.

    2006-11-17

    Weak gravitational lensing of distant galaxies by large scale structure (LSS) provides an unbiased way to map the matter distribution in the low redshift universe. This technique, based on the measurement of small distortions in the images of the source galaxies induced by the intervening LSS, is expected to become a key cosmological probe in the future. We discuss how future lensing surveys can probe the sum of the neutrino masses at the 0 05 eV level.

  17. Gravitational Particle Production in Braneworld Cosmology

    SciTech Connect

    Bambi, C.; Urban, F. R.

    2007-11-09

    Gravitational particle production in a time variable metric of an expanding universe is efficient only when the Hubble parameter H is not too small in comparison with the particle mass. In standard cosmology, the huge value of the Planck mass M{sub Pl} makes the mechanism phenomenologically irrelevant. On the other hand, in braneworld cosmology, the expansion rate of the early Universe can be much faster, and many weakly interacting particles can be abundantly created. Cosmological implications are discussed.

  18. Gravitational particle production in braneworld cosmology.

    PubMed

    Bambi, C; Urban, F R

    2007-11-01

    Gravitational particle production in a time variable metric of an expanding universe is efficient only when the Hubble parameter H is not too small in comparison with the particle mass. In standard cosmology, the huge value of the Planck mass M{Pl} makes the mechanism phenomenologically irrelevant. On the other hand, in braneworld cosmology, the expansion rate of the early Universe can be much faster, and many weakly interacting particles can be abundantly created. Cosmological implications are discussed. PMID:18233059

  19. Gravitational particle production in braneworld cosmology.

    PubMed

    Bambi, C; Urban, F R

    2007-11-01

    Gravitational particle production in a time variable metric of an expanding universe is efficient only when the Hubble parameter H is not too small in comparison with the particle mass. In standard cosmology, the huge value of the Planck mass M{Pl} makes the mechanism phenomenologically irrelevant. On the other hand, in braneworld cosmology, the expansion rate of the early Universe can be much faster, and many weakly interacting particles can be abundantly created. Cosmological implications are discussed.

  20. Weak Lie symmetry and extended Lie algebra

    SciTech Connect

    Goenner, Hubert

    2013-04-15

    The concept of weak Lie motion (weak Lie symmetry) is introduced. Applications given exhibit a reduction of the usual symmetry, e.g., in the case of the rotation group. In this context, a particular generalization of Lie algebras is found ('extended Lie algebras') which turns out to be an involutive distribution or a simple example for a tangent Lie algebroid. Riemannian and Lorentz metrics can be introduced on such an algebroid through an extended Cartan-Killing form. Transformation groups from non-relativistic mechanics and quantum mechanics lead to such tangent Lie algebroids and to Lorentz geometries constructed on them (1-dimensional gravitational fields).

  1. Exact Relativistic Newtonian Representation of Gravitational static Spacetime Geometries

    NASA Astrophysics Data System (ADS)

    Ghosh, Shubhrangshu; Sarkar, Tamal; Bhadra, Arunava

    2016-09-01

    We construct a self-consistent relativistic Newtonian analogue corresponding to gravitational static spherical symmetric spacetime geometries, starting directly from a generalized scalar relativistic gravitational action in a Newtonian framework, which gives geodesic equations of motion identical to those of the parent metric. Consequently, the derived velocity-dependent relativistic scalar potential, which is a relativistic generalization of the Newtonian gravitational potential, exactly reproduces the relativistic gravitational features corresponding to any static spherical symmetric spacetime geometry in its entirety, including all the experimentally tested gravitational effects in the weak field up to the present. This relativistic analogous potential is expected to be quite useful in studying a wide range of astrophysical phenomena, especially in strong field gravity.

  2. Dense neuron system interacting with the gravitational potential.

    PubMed

    Thuraisingham, R A

    2015-10-01

    A theoretical model is developed to study the role of the gravitational potential between neurons in the brain under conditions of zero gravity. The model includes firing and non-firing neurons in a neural network where the source of interaction is the gravitational potential. The importance of this study is its ability to examine the role of the weak gravitational potential alone without the inclusion of other interactions between neurons. The results of the study show density fluctuations contain components from thermal effects and gravitational interactions. It also shows collective oscillatory behavior amongst neurons from gravitational interactions. The study provides a simple alternate mechanism to understand organized behavior of neurons in the brain under conditions of zero gravity.

  3. Radio Astronomy

    NASA Technical Reports Server (NTRS)

    Wolken, P. R.; Shaffer, R. D.

    1983-01-01

    Deep Space Network (DSN) 26- and 64-meter antenna stations were utilized in support of Radio Astronomy Experiment Selection Panel experiments. Within a time span of 10 days, in May 1983 (267.75 hours total), nine RAES experiments were supported. Most of these experiments involved multifacility interferometry using Mark 3 data recording terminals and as many as six non-DSN observatories. Investigations of black holes, quasars, galaxies, and radio sources are discussed.

  4. On propagation of electromagnetic and gravitational waves in the expanding Universe

    NASA Astrophysics Data System (ADS)

    Gladyshev, V. O.

    2016-07-01

    The purpose of this study was to obtain an equation for the propagation time of electromagnetic and gravitational waves in the expanding Universe. The velocity of electromagnetic waves propagation depends on the velocity of the interstellar medium in the observer's frame of reference. Gravitational radiation interacts weakly with the substance, so electromagnetic and gravitational waves propagate from a remote astrophysical object to the terrestrial observer at different time. Gravitational waves registration enables the inverse problem solution - by the difference in arrival time of electromagnetic and gravitational-wave signal, we can determine the characteristics of the emitting area of the astrophysical object.

  5. Peculiar galaxies and radio sources.

    PubMed

    Arp, H

    1966-03-11

    Pairs of radio sources which are separated by from 2 degrees to 6 degrees on the sky have been investigated. In a number of cases peculiar galaxies have been found approximately midway along a line joining the two radio sources. The central peculiar galaxies belong mainly to a certain class in the recently compiled Atlas of Peculiar Galaxies. Among the radio sources so far associated with the peculiar galaxies are at least five known quasars. These quasars are indicated to be not at cosmological distances (that is, red shifts not caused by expansion of the universe) because the central peculiar galaxies are only at distances of 10 to 100 megaparsecs. The absolute magnitudes of these quasars are indicated to be in the range of brightness of normal galaxies and downward. Some of the radio sources which have been found to be associated with peculiar galaxies are galaxies themselves. It is therefore implied that ejection of material took place within or near the parent peculiar galaxies with speeds between 10(2) and 10(4) kilometers per second. After traveling for times of the order of 10(7) to 10(9) years, the luminous matter (galaxies) and radio sources (plasma) have reached their observed separations from the central peculiar galaxy. The large red shifts measured for the quasars would seem to be either (i) gravitational, (ii) collapse velocities of clouds of material falling toward the center of these compact galaxies, or (iii) some as yet unknown cause.

  6. The gravitational wave decade

    NASA Astrophysics Data System (ADS)

    Conklin, John

    2016-03-01

    With the expected direct detection of gravitational waves by Advanced LIGO and pulsar timing arrays in the near future, and with the recent launch of LISA Pathfinder this can arguably be called the decade of gravitational waves. Low frequency gravitational waves in the mHz range, which can only be observed from space, provide the richest science and complement high frequency observatories on the ground. A space-based observatory will improve our understanding of the formation and growth of massive black holes, create a census of compact binary systems in the Milky Way, test general relativity in extreme conditions, and enable searches for new physics. LISA, by far the most mature concept for detecting gravitational waves from space, has consistently ranked among the nation's top priority large science missions. In 2013, ESA selected the science theme ``The Gravitational Universe'' for its third large mission, L3, under the Cosmic Visions Program, with a planned launch date of 2034. NASA has decided to join with ESA on the L3 mission as a junior partner and has recently assembled a study team to provide advice on how NASA might contribute to the European-led mission. This talk will describe these efforts and the activities of the Gravitational Wave Science Interest Group and the L3 Study Team, which will lead to the first space-based gravitational wave observatory.

  7. Astronomers Discover Six-Image Gravitational Lens

    NASA Astrophysics Data System (ADS)

    2001-08-01

    An international team of astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope and NASA's Hubble Space Telescope (HST) to discover the first gravitational lens in which the single image of a very distant galaxy has been split into six different images. The unique configuration is produced by the gravitational effect of three galaxies along the line of sight between the more-distant galaxy and Earth. Optical and Radio Images of Gravitational Lens "This is the first gravitational lens with more than four images of the background object that is produced by a small group of galaxies rather than a large cluster of galaxies," said David Rusin, who just received his Ph.D. from the University of Pennsylvania. "Such systems are expected to be extremely rare, so this discovery is an important stepping stone. Because this is an intermediate case between gravitational lenses produced by single galaxies and lenses produced by large clusters of galaxies, it will give us insights we can't get from other types of lenses," Rusin added. The gravitational lens, called CLASS B1359+154, consists of a galaxy more than 11 billion light-years away in the constellation Bootes, with a trio of galaxies more than 7 billion light-years away along the same line of sight. The more-distant galaxy shows signs that it contains a massive black hole at its core and also has regions in which new stars are forming. The gravitational effect of the intervening galaxies has caused the light and radio waves from the single, more-distant galaxy to be "bent" to form six images as seen from Earth. Four of these images appear outside the triangle formed by the three intermediate galaxies and two appear inside that triangle. "This lens system is a very interesting case to study because it is more complicated than lenses produced by single galaxies, and yet simpler than lenses produced by clusters of numerous galaxies," said Chris Kochanek of the Harvard

  8. Towards Gravitational Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Losurdo, Giovanni

    This chapter is meant to introduce the reader to the forthcoming network of second-generation interferometric detectors of gravitational waves, at a time when their construction is close to completion and there is the ambition to detect gravitational waves for the first time in the next few years and open the way to gravitational wave astronomy. The legacy of first-generation detectors is discussed before giving an overview of the technology challenges that have been faced to make advanced detectors possible. The various aspects outlined here are then discussed in more detail in the subsequent chapters of the book.

  9. Inverting Gravitational Lenses

    NASA Astrophysics Data System (ADS)

    Newbury, P. R.; Spiteri, R. J.

    2002-02-01

    Gravitational lensing provides a powerful tool to study a number of fundamental questions in astrophysics. Fortuitously, one can begin to explore some non-trivial issues associated with this phenomenon without a lot of very sophisticated mathematics, making an elementary treatment of this topic tractable even to senior undergraduates. In this paper, we give a relatively self-contained outline of the basic concepts and mathematics behind gravitational lensing as a recent and exciting topic for courses in mathematical modeling or scientific computing. To this end, we have designed and made available some interactive software to aid in the simulation and inversion of gravitational lenses in a classroom setting.

  10. Basic Radio Circuits and Vacuum Tube AM Troubleshooting; Radio and Television Service, Intermediate: 9785.03.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    The 135-hour quinmester course covers study of basic radio circuits as applied to vacuum tube radios in six blocks of instruction: orientation; AM receivers with tubes; no signal, audio failure; distortion; weak, noisy signals; and a post-test. Each block is subdivided into several units, and block objectives are outlined. Completion of AC…

  11. Astronomers Discover Six-Image Gravitational Lens

    NASA Astrophysics Data System (ADS)

    2001-08-01

    An international team of astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope and NASA's Hubble Space Telescope (HST) to discover the first gravitational lens in which the single image of a very distant galaxy has been split into six different images. The unique configuration is produced by the gravitational effect of three galaxies along the line of sight between the more-distant galaxy and Earth. Optical and Radio Images of Gravitational Lens "This is the first gravitational lens with more than four images of the background object that is produced by a small group of galaxies rather than a large cluster of galaxies," said David Rusin, who just received his Ph.D. from the University of Pennsylvania. "Such systems are expected to be extremely rare, so this discovery is an important stepping stone. Because this is an intermediate case between gravitational lenses produced by single galaxies and lenses produced by large clusters of galaxies, it will give us insights we can't get from other types of lenses," Rusin added. The gravitational lens, called CLASS B1359+154, consists of a galaxy more than 11 billion light-years away in the constellation Bootes, with a trio of galaxies more than 7 billion light-years away along the same line of sight. The more-distant galaxy shows signs that it contains a massive black hole at its core and also has regions in which new stars are forming. The gravitational effect of the intervening galaxies has caused the light and radio waves from the single, more-distant galaxy to be "bent" to form six images as seen from Earth. Four of these images appear outside the triangle formed by the three intermediate galaxies and two appear inside that triangle. "This lens system is a very interesting case to study because it is more complicated than lenses produced by single galaxies, and yet simpler than lenses produced by clusters of numerous galaxies," said Chris Kochanek of the Harvard

  12. Rosetta Radio Science Investigations (RSI)

    NASA Astrophysics Data System (ADS)

    Pätzold, Martin; Häusler, Bernd; Aksnes, Kaare; Anderson, John D.; Asmar, Sami W.; Barriot, Jean-Pierre; Bird, Michael K.; Boehnhardt, Hermann; Eidel, Werner; Grün, Eberhardt; Ip, Wing H.; Marouf, Essam; Morley, Trevor; Neubauer, Fritz M.; Rickman, Hans; Thomas, Nicolas; Tsurutani, Bruce T.; Wallis, Max K.; Wickramasinghe, N. C.; Mysen, Eirik; Olson, Oystein; Remus, Stefan; Tellmann, Silvia; Andert, Thomas; Carone, Ludmila; Fels, Markus; Stanzel, Christina; Audenrieth-Kersten, Iris; Gahr, Alexander; Müller, Anna-Liane; Stupar, Dusan; Walter, Christina

    2007-02-01

    The Rosetta spacecraft has been successfully launched on 2nd March 2004 to its new target comet 67 P/Churyumov-Gerasimenko. The science objectives of the Rosetta Radio Science Investigations (RSI) experiment address fundamental aspects of cometary physics such as the mass and bulk density of the nucleus, its gravity field, its interplanetary orbit perturbed by nongravitational forces, its size and shape, its internal structure, the composition and roughness of the nucleus surface, the abundance of large dust grains, the plasma content in the coma and the combined dust and gas mass flux. The masses of two asteroids, Steins and Lutetia, shall be determined during flybys in 2008 and 2010, respectively. Secondary objectives are the radio sounding of the solar corona during the superior conjunctions of the spacecraft with the Sun during the cruise phase. The radio carrier links of the spacecraft Telemetry, Tracking and Command (TT&C) subsystem between the orbiter and the Earth will be used for these investigations. An Ultrastable oscillator (USO) connected to both transponders of the radio subsystem serves as a stable frequency reference source for both radio downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) in the one-way mode. The simultaneous and coherent dual-frequency downlinks via the High Gain Antenna (HGA) permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarization and propagation times of radio signals transmitted from the spacecraft and received with ground station antennas on Earth. The radio signals are affected by the medium through which the signals propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and

  13. Gravitational lenses, cosmology, and galaxy structure

    NASA Astrophysics Data System (ADS)

    Winn, J.

    2002-05-01

    Gravitational lenses can be used to study dark matter in galaxies and to measure the Hubble constant. The statistics of lensing can be used to measure the cosmological constant. I have been conducting a survey of the southern sky for new lenses at radio wavelengths, which has resulted in 4 confirmed lenses and 3 strong candidates that require further follow-up. I will describe the survey and the scientific results that have been obtained from the new lenses. I will also describe my other life as a science journalist.

  14. Gravitational-wave joy

    NASA Astrophysics Data System (ADS)

    seyithocuk; jjeherrera; eltodesukane; GrahamRounce; rloldershaw; Beaker, Dr; Sandhu, G. S.; Ophiuchi

    2016-03-01

    In reply to the news article on the LIGO collaboration's groundbreaking detection of gravitational waves, first predicted by Einstein 100 years ago, from two black holes colliding (pp5, 6-7 and http://ow.ly/Ylsyt).

  15. Gravitational clustering: an overview

    NASA Astrophysics Data System (ADS)

    Labini, Francesco Sylos

    2008-01-01

    We discuss the differences and analogies of gravitational clustering in finite and infinite systems. The process of collective, or violent, relaxation leading to the formation of quasi-stationary states is one of the distinguished features in the dynamics of self-gravitating systems. This occurs, in different conditions, both in a finite than in an infinite system, the latter embedded in a static or in an expanding background. We then discuss, by considering some simple and paradigmatic examples, the problems related to the definition of a mean-field approach to gravitational clustering, focusing on role of discrete fluctuations. The effect of these fluctuations is a basic issue to be clarified to establish the range of scales and times in which a collision-less approximation may describe the evolution of a self-gravitating system and for the theoretical modeling of the non-linear phase.

  16. Radio astronomy

    NASA Technical Reports Server (NTRS)

    Kellermann, Kenneth I.; Heeschen, David; Backer, Donald C.; Cohen, Marshall H.; Davis, Michael; Depater, Imke; Deyoung, David; Dulk, George A.; Fisher, J. R.; Goss, W. Miller

    1991-01-01

    The following subject areas are covered: (1) scientific opportunities (millimeter and sub-millimeter wavelength astronomy; meter to hectometer astronomy; the Sun, stars, pulsars, interstellar masers, and extrasolar planets; the planets, asteroids, and comets; radio galaxies, quasars, and cosmology; and challenges for radio astronomy in the 1990's); (2) recommendations for new facilities (the millimeter arrays, medium scale instruments, and small-scale projects); (3) continuing activities and maintenance, upgrading of telescopes and instrumentation; (4) long range programs and technology development; and (5) social, political, and organizational considerations.

  17. The double quasar 0957+561: a radio study at 6-centimeters wavelength.

    PubMed

    Roberts, D H; Greenfield, P E; Burke, B F

    1979-08-31

    The optical double quasar 0957+561 has been interpreted as the gravitational double image of a single object. A radio map made with the Very Large Array of the National Radio Astronomy Observatory shows unresolved sources coincident With the optical images as well as a complex of related extended emission. Although the results cannot rule out the gravitational lens hypothesis, the complex radio structure is more easily interpreted as two separate quasars. The optical and radio properties of the two quasars are so similar that the two must have been formed at the same time with similar initial conditions.

  18. Mass ejection from neutron star mergers: different components and expected radio signals

    NASA Astrophysics Data System (ADS)

    Hotokezaka, Kenta; Piran, Tsvi

    2015-06-01

    In addition to producing a strong gravitational signal, a short gamma-ray burst (GRB), and a compact remnant, neutron star mergers eject significant masses (up to a few per cent of M⊙) at significant kinetic energies. The different components of the ejected mass include a dynamical ejected mass, a GRB jet and also a shock-breakout material, a cocoon resulting from the interaction of the jet with other ejecta, and viscous- and neutrino-driven winds. The interaction of these ejecta with the surrounding interstellar medium will produce a long-lasting radio flare. We estimate here the expected radio flares arising from these outflows. The flares are rather weak and uncertainties in the kinetic energy, the velocity, and the external density make exact estimates of these signals difficult. The relative strength of the different signals depends strongly on the viewing angle. An observer along the jet axis or close to it will detect a strong signal at a few dozen days from the radio afterglow (or the orphan radio afterglow) produced by the highly relativistic GRB jet. A generic observer at larger viewing angles will generally observe the dynamical ejecta, whose contribution peaks a year or so after the event. Depending on the observed frequency and the external density, other components may also give rise to a significant contribution. If the short GRB 130603B was a merger event, its radio flare from the dynamical ejecta might be detectable with the EVLA and the LOFAR for the higher range of external densities n ≳ 0.5 cm-3

  19. Weak scale supersymmetry

    SciTech Connect

    Hall, L.J. California Univ., Berkeley, CA . Dept. of Physics)

    1990-11-12

    An introduction to the ideas and current state of weak scale supersymmetry is given. It is shown that LEP data on Z decays has already excluded two of the most elegant models of weak scale supersymmetry. 14 refs.

  20. Simulating Weak Lensing by Large-Scale Structure

    NASA Astrophysics Data System (ADS)

    Vale, Chris; White, Martin

    2003-08-01

    We model weak gravitational lensing of light by large-scale structure using ray tracing through N-body simulations. The method is described with particular attention paid to numerical convergence. We investigate some of the key approximations in the multiplane ray-tracing algorithm. Our simulated shear and convergence maps are used to explore how well standard assumptions about weak lensing hold, especially near large peaks in the lensing signal.

  1. A Xylophone Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo

    1997-01-01

    We discuss spacecraft Doppler tracking searches for gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we describe a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. This technique provides also a way for reducing by several orders of magnitude, at selected Fourier components, the frequency fluctuations due to other noise sources, such as the clock on board the spacecraft or the antenna and buffeting of the probe by nongravitational forces. In this respect spacecraft Doppler tracking can be regarded as a xylophone detector of gravitational radiation. In the assumption of calibrating the frequency fluctuations induced by the interplanetary plasma, a strain sensitivity equal to 4.7 x 10(exp -18) at 10(exp -3) Hz is estimated. This experimental technique could be extended to other tests of the theory of relativity, and to radio science experiments that rely on high-precision Doppler measurements.

  2. HST Observations of New Class Gravitational Lenses

    NASA Astrophysics Data System (ADS)

    Jackson, Neal

    1995-07-01

    We propose to examine a few of the very best lens candidates from a new gravitational lens survey, the Cosmic Lens All-Sky Survey (CLASS) made with the VLA. We are virtually certain that we have one new lens system (1600+434) and another (1609+655) has a radio configuration which almost invariably indicates gravitational lensing. The other cases are systems which have a high probability of being lenses (statistically we would expect at least 5 of the 10 objects should be lensed, since we have imaged >3000 radio sources and experience shows that 1 in 500 are lensed). All have separations which make them difficult to study from the ground and therefore uniquely suited to the capabilities of the HST. In this investigation we will study 1600+434 and 1609+655 and attempt to image the lensing galaxy. We will image the remainder in an attempt to confirm their lens status (which requires 0.1" resolution imaging typically) and search for lensing galaxies and/or clusters in those found to be lensed systems.

  3. Cosmic matter-antimatter asymmetry and gravitational force

    NASA Technical Reports Server (NTRS)

    Hsu, J. P.

    1980-01-01

    Cosmic matter-antimatter asymmetry due to the gravitational interaction alone is discussed, considering the gravitational coupling of fermion matter related to the Yang-Mills (1954) gauge symmetry with the unique generalization of the four-dimensional Poincare group. Attention is given to the case of weak static fields which determines the space-time metric where only large source terms are retained. In addition, considering lowest-order Feynman diagrams, there are presented gravitational potential energies between fermions, between antifermions, and between a fermion and an antifermion. It is concluded that the gravitational force between matter is different from that between antimatter; implications from this concerning the evolution of the universe are discussed.

  4. Sources of gravitational waves

    NASA Technical Reports Server (NTRS)

    Schutz, Bernard F.

    1989-01-01

    Sources of low frequency gravitational radiation are reviewed from an astrophysical point of view. Cosmological sources include the formation of massive black holes in galactic nuclei, the capture by such holes of neutron stars, the coalescence of orbiting pairs of giant black holes, and various means of producing a stochastic background of gravitational waves in the early universe. Sources local to our Galaxy include various kinds of close binaries and coalescing binaries. Gravitational wave astronomy can provide information that no other form of observing can supply; in particular, the positive identification of a cosmological background originating in the early universe would be an event as significant as was the detection of the cosmic microwave background.

  5. Modeling Gravitational Radiation Waveforms from Black Hole Mergers

    NASA Technical Reports Server (NTRS)

    Baker, J. G.; Centrelia, J. M.; Choi, D.; Koppitz, M.; VanMeter, J.

    2006-01-01

    Gravitational radiation from merging binary black hole systems is anticipated as a key source for gravitational wave observations. Ground-based instruments, such as the Laser Interferometer Gravitational-wave Observatory (LIGO) may observe mergers of stellar-scale black holes, while the space-based Laser Interferometer Space Antenna (LISA) observatory will be sensitive to mergers of massive galactic-center black holes over a broad range of mass scales. These cataclysmic events may emit an enormous amount of energy in a brief time. Gravitational waves from comparable mass mergers carry away a few percent of the system's mass-energy in just a few wave cycles, with peak gravitational wave luminosities on the order of 10^23 L_Sun. Optimal analysis and interpretation of merger observation data will depend on developing a detailed understanding, based on general relativistic modeling, of the radiation waveforms. We discuss recent progress in modeling radiation from equal mass mergers using numerical simulations of Einstein's gravitational field equations, known as numerical relativity. Our simulations utilize Adaptive Mesh Refinement (AMR) to allow high-resolution near the black holes while simultaneously keeping the outer boundary of the computational domain far from the black holes, and making it possible to read out gravitational radiation waveforms in the weak-field wave zone. We discuss the results from simulations beginning with the black holes orbiting near the system's innermost stable orbit, comparing the recent simulations with earlier "Lazarus" waveform estimates based on an approximate hybrid numerical/perturbative technique.

  6. On the gravitational redshift

    NASA Astrophysics Data System (ADS)

    Wilhelm, Klaus; Dwivedi, Bhola N.

    2014-08-01

    The study of the gravitational redshift-a relative wavelength increase of ≈2×10-6 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 ratio of 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 in such an atom is approximately 3×10-21. A comparison of this ratio with the predicted and observed solar redshift indicates a discrepancy of many orders of magnitude. With Einstein’s early assumption that the frequencies of spectral lines depend only on the generating ions themselves as starting point, we show 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.

  7. The Radio JOVE Project - Shoestring Radio Astronomy

    NASA Technical Reports Server (NTRS)

    Thieman, J.; Flagg, R.; Greenman, W.; Higgins, C.; Reyes, F.; Sky, J.

    2010-01-01

    Radio JOVE is an education and outreach project intended to give students and other interested individuals hands-on experience in learning radio astronomy. They can do this through building a radio telescope from a relatively inexpensive kit that includes the parts for a receiver and an antenna as well as software for a computer chart recorder emulator (Radio Skypipe) and other reference materials

  8. Response of a Doppler canceling system to plane gravitational waves

    NASA Technical Reports Server (NTRS)

    Caporali, A.

    1982-01-01

    This paper discusses the interaction of long periodic gravitational waves with a three-link microwave system known as the Doppler canceling system. This system, which was developed for a gravitational red-shift experiment, uses one-way and two-way Doppler information to construct the beat signal of two reference oscillators moving with respect to each other. The geometric-optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational-wave space-time. The signature left on the Doppler-cancelled beat by bursts and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler canceling system and that of a (NASA) Doppler tracking system which employs two-way, round-trip radio waves. A threefold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.

  9. Gravitational-Wave Astronomy

    NASA Technical Reports Server (NTRS)

    Kelly, Bernard J.

    2010-01-01

    Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.

  10. Supersymmetry and gravitational duality

    SciTech Connect

    Argurio, Riccardo; Dehouck, Francois; Houart, Laurent

    2009-06-15

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

  11. Galaxies as gravitational lenses.

    PubMed

    Barnothy, J; Barnothy, M F

    1968-10-18

    Of all the galaxies in the visible part of the universe, 500 million are seen through intervening galaxies. In some instances the foreground galaxy will act as a gravitational lens and produce distorted and (in brightness) greatly amplified images of the galaxy behind it; such images may simulate starlike superluminous objects such as quasars (quasi-stellar objects). The number of gravitational lenses is several times greater than the number of quasars yet observed. In other instances the superposition of the image upon a visible foreground galaxy may simulate morphological configurations resembling N-type, dumbbell, spiral, or barred-spiral galaxies. PMID:17836654

  12. Gravitation: Foundations and Frontiers

    NASA Astrophysics Data System (ADS)

    Padmanabhan, T.

    2010-01-01

    1. Special relativity; 2. Scalar and electromagnetic fields in special relativity; 3. Gravity and spacetime geometry: the inescapable connection; 4. Metric tensor, geodesics and covariant derivative; 5. Curvature of spacetime; 6. Einstein's field equations and gravitational dynamics; 7. Spherically symmetric geometry; 8. Black holes; 9. Gravitational waves; 10. Relativistic cosmology; 11. Differential forms and exterior calculus; 12. Hamiltonian structure of general relativity; 13. Evolution of cosmological perturbations; 14. Quantum field theory in curved spacetime; 15. Gravity in higher and lower dimensions; 16. Gravity as an emergent phenomenon; Notes; Index.

  13. Scalar Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Mottola, Emil

    2016-03-01

    General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degree of freedom in the extended effective field theory (EFT) of gravity generated by the trace anomaly of massless quantum fields in curved space. Linearized around flat space this quantum scalar degree of freedom combines with the conformal part of the metric and predicts the existence of scalar spin-0 ``breather'' propagating gravitational waves in addition to the transverse tensor spin-2 waves of classical General Relativity. Estimates of the expected strength of scalar gravitational radiation from compact astrophysical sources are given.

  14. Space Telecommunications Radio System STRS Cognitive Radio

    NASA Technical Reports Server (NTRS)

    Briones, Janette C.; Handler, Louis M.

    2013-01-01

    Radios today are evolving from awareness toward cognition. A software defined radio (SDR) provides the most capability for integrating autonomic decision making ability and allows the incremental evolution toward a cognitive radio. This cognitive radio technology will impact NASA space communications in areas such as spectrum utilization, interoperability, network operations, and radio resource management over a wide range of operating conditions. NASAs cognitive radio will build upon the infrastructure being developed by Space Telecommunication Radio System (STRS) SDR technology. This paper explores the feasibility of inserting cognitive capabilities in the NASA STRS architecture and the interfaces between the cognitive engine and the STRS radio. The STRS architecture defines methods that can inform the cognitive engine about the radio environment so that the cognitive engine can learn autonomously from experience, and take appropriate actions to adapt the radio operating characteristics and optimize performance.

  15. Postselected weak measurement beyond the weak value

    SciTech Connect

    Geszti, Tamas

    2010-04-15

    Closed expressions are derived for the quantum measurement statistics of pre- and postselected Gaussian particle beams. The weakness of the preselection step is shown to compete with the nonorthogonality of postselection in a transparent way. The approach is shown to be useful in analyzing postselection-based signal amplification, allowing measurements to be extended far beyond the range of validity of the well-known Aharonov-Albert-Vaidman limit. Additionally, the present treatment connects postselected weak measurement to the topic of phase-contrast microscopy.

  16. Exploring the nature of radio relics and halos in galaxy clusters through GHz radio observations

    NASA Astrophysics Data System (ADS)

    Trasatti, M.

    2014-11-01

    Clusters of galaxies are the largest gravitationally bound systems in the Universe. A fraction of them hosts diffuse Mpc-scale synchrotron sources (referred to as radio relics and radio halos) not related to any discrete cluster member, but rather to the diffuse medium. The emission from these sources helps in unambiguously prove the presence of weak magnetic fields and non-thermal plasma in the intra-cluster medium (ICM) of galaxy clusters, coexisting with the hot thermal component emitting X-rays. The radio emitting electrons, given their relatively short lifetime respect to the extent of these sources, must have undergone some form of acceleration. It is widely believed that they are connected to the most energetic phenomena in the Universe, mergers between clusters, during which shocks and turbulence may develop in the ICM leading eventually to the acceleration of particles through Fermi mechanisms. Both phenomena are, indeed, mostly observed in galaxy clusters with a disturbed dynamical state. However, the details of the acceleration mechanisms are still greatly debated. According to the proposed models, the currently known radio relics and halos are the most energetic cases, for which relatively high-frequency observations are necessary in order to test the models expectations. However, for most of them the highest studied frequency is 1.4 GHz. In this thesis we studied the properties of this kind of sources at frequencies > 1 GHz. We mainly focused on two clusters, Abell 1656 (best known as the Coma cluster) and Abell 2256, known to possess both a radio relic and a radio halo. We observed a wide field on the Coma cluster, covering both the peripheral relic and the central halo, with the Effelsberg 100-m telescope at 1400 MHz. Moreover, the Coma relic field and the Coma halo field have been covered separately with respectively a 3-pointing and a 9-pointing mosaics performed with the WSRT at 2273 MHz. We have observed the cluster Abell 2256 with the Effelsberg

  17. Astronomers Get New Tools for Gravitational-Wave Detection

    NASA Astrophysics Data System (ADS)

    2010-01-01

    Teamwork between gamma-ray and radio astronomers has produced a breakthrough in finding natural cosmic tools needed to make the first direct detections of the long-elusive gravitational waves predicted by Albert Einstein nearly a century ago. An orbiting gamma-ray telescope has pointed radio astronomers to specific locations in the sky where they can discover new millisecond pulsars. Millisecond pulsars, rapidly-spinning superdense neutron stars, can serve as extremely precise and stable natural clocks. Astronomers hope to detect gravitational waves by measuring tiny changes in the pulsars' rotation caused by the passage of the gravitational waves. To do this, they need a multitude of millisecond pulsars dispersed widely throughout the sky. However, nearly three decades after the discovery of the first millisecond pulsar, only about 150 of them had been found, some 90 of those clumped tightly in globular star clusters and thus unusable for detecting gravitational waves. The problem was that millisecond pulsars could only be discovered through arduous, computing-intensive searches of small portions of sky. "We've probably found far less than one percent of the millisecond pulsars in the Milky Way Galaxy," said Scott Ransom of the National Radio Astronomy Observatory (NRAO). The breakthrough came when an instrument aboard NASA's Fermi Gamma-Ray Space Telescope began surveying the sky in 2008. This instrument located hundreds of gamma-ray-emitting objects throughout our Galaxy, and astronomers suspected many of these could be millisecond pulsars. Paul Ray of the Naval Research Laboratory initiated an international collaboration to use radio telescopes to confirm the identity of these objects as millisecond pulsars. "The data from Fermi were like a buried-treasure map," Ransom said. "Using our radio telescopes to study the objects located by Fermi, we found 17 millisecond pulsars in three months. Large-scale searches had taken 10-15 years to find that many," Ransom

  18. Gravitational Waves: The Evidence Mounts

    ERIC Educational Resources Information Center

    Wick, Gerald L.

    1970-01-01

    Reviews the work of Weber and his colleagues in their attempts at detecting extraterrestial gravitational waves. Coincidence events recorded by special detectors provide the evidence for the existence of gravitational waves. Bibliography. (LC)

  19. Gravitational lenses and particle properties

    NASA Technical Reports Server (NTRS)

    Turner, Edwin L.

    1986-01-01

    The potential of observations of gravitational lens systems for the determination of cosmological constants and for tests of the nature and distribution of dark matter is illustrated. The advantages and disadvantages of gravitational lenses as cosmological probes are evaluated.

  20. The Search for HI Emission at z ≈ 0.4 in Gravitationally Lensed Galaxies with the Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Hunt, L. R.; Pisano, D. J.; Edel, S.

    2016-08-01

    Neutral hydrogen (Hi) provides a very important fuel for star formation, but is difficult to detect at high redshift due to weak emission, limited sensitivity of modern instruments, and terrestrial radio frequency interference (RFI) at low frequencies. We report the first attempt to use gravitational lensing to detect Hi line emission from three gravitationally lensed galaxies behind the cluster Abell 773, two at redshifts of 0.398 and one at z = 0.487, using the Green Bank Telescope. We find that a 3σ upper limit for a galaxy with a rotation velocity of 200 km s‑1 is M H i = 6.58 × 109 and 1.5 × 1010 M ⊙ at z = 0.398 and z = 0.487. The estimated Hi masses of the sources at z = 0.398 and z = 0.487 are factors of 3.7 and ˜30 times lower than our detection limits at the respective redshifts. To facilitate these observations we have used sigma-clipping to remove both narrow- and wideband RFI but retain the signal from the source. We are able to reduce the noise of the spectrum by ˜25% using our routine instead of discarding observations with too much RFI. The routine is most effective when ˜10% of the integrations or fewer contain RFI. These techniques can be used to study Hi in highly magnified distant galaxies that are otherwise too faint to detect.

  1. The Search for HI Emission at z ≈ 0.4 in Gravitationally Lensed Galaxies with the Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Hunt, L. R.; Pisano, D. J.; Edel, S.

    2016-08-01

    Neutral hydrogen (Hi) provides a very important fuel for star formation, but is difficult to detect at high redshift due to weak emission, limited sensitivity of modern instruments, and terrestrial radio frequency interference (RFI) at low frequencies. We report the first attempt to use gravitational lensing to detect Hi line emission from three gravitationally lensed galaxies behind the cluster Abell 773, two at redshifts of 0.398 and one at z = 0.487, using the Green Bank Telescope. We find that a 3σ upper limit for a galaxy with a rotation velocity of 200 km s-1 is M H i = 6.58 × 109 and 1.5 × 1010 M ⊙ at z = 0.398 and z = 0.487. The estimated Hi masses of the sources at z = 0.398 and z = 0.487 are factors of 3.7 and ˜30 times lower than our detection limits at the respective redshifts. To facilitate these observations we have used sigma-clipping to remove both narrow- and wideband RFI but retain the signal from the source. We are able to reduce the noise of the spectrum by ˜25% using our routine instead of discarding observations with too much RFI. The routine is most effective when ˜10% of the integrations or fewer contain RFI. These techniques can be used to study Hi in highly magnified distant galaxies that are otherwise too faint to detect.

  2. Numerical solution of an elastic and viscoelastic gravitational models by the finite element method

    NASA Astrophysics Data System (ADS)

    Arjona Almodóvar, A.; Chacón Rebollo, T.; Gómez Marmol, M.

    2014-12-01

    Volcanic areas present a lower effective viscosity than usually in the Earth's crust. Both the elastic-gravitational and the viscoelastic-gravitational models allow the computation of gravity, deformation, and gravitational potential changes in order to investigate crustal deformations of Earth (see for instance Battaglia & Segall, 2004; Fernández et al. 1999, 2001; Rundle 1980 and 1983). These models can be represented by a coupled system of linear parabolic (for the elastic deformations), hyperbolic (for the viscoelastic deformations) and elliptic partial differential equations (for gravitational potential changes) (see for instance Arjona et al. 2008 and 2010). The existence and uniqueness of weak solutions for both the elastic-gravitational and viscoelastic-gravitational problem was demonstrated in Arjona et al. (2008 and 2014). The stabilization to solutions of the associated stationary system was proved in Arjona and Díaz (2007). Here we consider the internal source as response to the effect of a pressurized magma reservoir into a multilayered, elastic-gravitational and viscoelastic-gravitational earth model. We introduce the numerical analysis of a simplified steady elastic-gravitational model, solved by means of the finite element method. We also present some numerical tests in realistic situations that confirm the predictions of theoretical order of convergence. Finally, we describe the methodology for both the elastic-gravitational and the viscoelastic-gravitational models using 2D and 3D test examples performed with FreeFEM++.

  3. Research on gravitational physiology

    NASA Technical Reports Server (NTRS)

    Brown, A. H.; Dahl, A. O.

    1974-01-01

    The topic of gravitational plant physiology was studied through aspects of plant development (in ARABIDOPSIS) and of behavior (in HELIANTHUS) as these were affected by altered g experience. The effect of increased g levels on stem polarity (in COLEUS) was also examined.

  4. Criteria for observation of the gravitational lens effect

    SciTech Connect

    Mitskevich, N.V.

    1980-11-01

    In connection with the possible interpretation of observations of the double quasar 0957+561 as a manifestation of the gravitational lens effect, the problem of testing the coherence of the emission of the two sources in the optical and radio ranges and possible distortions of the interference pattern due to such coherence is discussed. The importance of observing time variations in the appearance of the sources is also noted.

  5. Retro gravitational lensing for Sgr A* with Radiastron

    NASA Astrophysics Data System (ADS)

    Zakharov, A. F.; Nucita, A. A.; de Paolis, F.; Ingrosso, G.

    2005-03-01

    Recently Holz & Wheeler (2002) have considered a very attractive possibility to detect retro-MACHOs, i.e. retro-images of the Sun by a Schwarzschild black hole. We analyze the case of a Kerr black hole with an arbitrary spin for some selected positions of a distant observer with respect to the equatorial plane of a Kerr black hole. We discuss glories (mirages) formed near rapidly rotating Kerr black hole horizons and propose a procedure to measure masses and rotation parameters by analyzing these forms of mirages. In some sense, that is a manifestation of gravitational lens effect in the strong gravitational field near the black hole horizon and a generalization of the retro-gravitational lens phenomenon. We also propose to use future radio interferometer Radioastron facilities to measure shapes of mirages (glories) and to evaluate the black hole spin as a function of the position angle of a distant observer.

  6. Detecting stochastic backgrounds of gravitational waves with pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Siemens, Xavier

    2016-03-01

    For the past decade the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has been using the Green Bank Telescope and the Arecibo Observatory to monitor millisecond pulsars. NANOGrav, along with two other international collaborations, the European Pulsar Timing Array and the Parkes Pulsar Timing Array in Australia, form a consortium of consortia: the International Pulsar Timing Array (IPTA). The goal of the IPTA is to directly detect low-frequency gravitational waves which cause small changes to the times of arrival of radio pulses from millisecond pulsars. In this talk I will discuss the work of NANOGrav and the IPTA, as well as our sensitivity to stochastic backgrounds of gravitational waves. I will show that a detection of the background produced by supermassive black hole binaries is possible by the end of the decade. Supported by the NANOGrav Physics Frontiers Center.

  7. Nanohertz gravitational wave searches with interferometric pulsar timing experiments.

    PubMed

    Tinto, Massimo

    2011-05-13

    We estimate the sensitivity to nano-Hertz gravitational waves of pulsar timing experiments in which two highly stable millisecond pulsars are tracked simultaneously with two neighboring radio telescopes that are referenced to the same timekeeping subsystem (i.e., "the clock"). By taking the difference of the two time-of-arrival residual data streams we can exactly cancel the clock noise in the combined data set, thereby enhancing the sensitivity to gravitational waves. We estimate that, in the band (10(-9)-10(-8))  Hz, this "interferometric" pulsar timing technique can potentially improve the sensitivity to gravitational radiation by almost 2 orders of magnitude over that of single-telescopes. Interferometric pulsar timing experiments could be performed with neighboring pairs of antennas of the NASA's Deep Space Network and the forthcoming large arraying projects.

  8. Nanohertz gravitational wave searches with interferometric pulsar timing experiments.

    PubMed

    Tinto, Massimo

    2011-05-13

    We estimate the sensitivity to nano-Hertz gravitational waves of pulsar timing experiments in which two highly stable millisecond pulsars are tracked simultaneously with two neighboring radio telescopes that are referenced to the same timekeeping subsystem (i.e., "the clock"). By taking the difference of the two time-of-arrival residual data streams we can exactly cancel the clock noise in the combined data set, thereby enhancing the sensitivity to gravitational waves. We estimate that, in the band (10(-9)-10(-8))  Hz, this "interferometric" pulsar timing technique can potentially improve the sensitivity to gravitational radiation by almost 2 orders of magnitude over that of single-telescopes. Interferometric pulsar timing experiments could be performed with neighboring pairs of antennas of the NASA's Deep Space Network and the forthcoming large arraying projects. PMID:21668135

  9. Aperiodic Weak Topological Superconductors

    NASA Astrophysics Data System (ADS)

    Fulga, I. C.; Pikulin, D. I.; Loring, T. A.

    2016-06-01

    Weak topological phases are usually described in terms of protection by the lattice translation symmetry. Their characterization explicitly relies on periodicity since weak invariants are expressed in terms of the momentum-space torus. We prove the compatibility of weak topological superconductors with aperiodic systems, such as quasicrystals. We go beyond usual descriptions of weak topological phases and introduce a novel, real-space formulation of the weak invariant, based on the Clifford pseudospectrum. A nontrivial value of this index implies a nontrivial bulk phase, which is robust against disorder and hosts localized zero-energy modes at the edge. Our recipe for determining the weak invariant is directly applicable to any finite-sized system, including disordered lattice models. This direct method enables a quantitative analysis of the level of disorder the topological protection can withstand.

  10. Aperiodic Weak Topological Superconductors.

    PubMed

    Fulga, I C; Pikulin, D I; Loring, T A

    2016-06-24

    Weak topological phases are usually described in terms of protection by the lattice translation symmetry. Their characterization explicitly relies on periodicity since weak invariants are expressed in terms of the momentum-space torus. We prove the compatibility of weak topological superconductors with aperiodic systems, such as quasicrystals. We go beyond usual descriptions of weak topological phases and introduce a novel, real-space formulation of the weak invariant, based on the Clifford pseudospectrum. A nontrivial value of this index implies a nontrivial bulk phase, which is robust against disorder and hosts localized zero-energy modes at the edge. Our recipe for determining the weak invariant is directly applicable to any finite-sized system, including disordered lattice models. This direct method enables a quantitative analysis of the level of disorder the topological protection can withstand. PMID:27391744

  11. LensTools: Weak Lensing computing tools

    NASA Astrophysics Data System (ADS)

    Petri, A.

    2016-02-01

    LensTools implements a wide range of routines frequently used in Weak Gravitational Lensing, including tools for image analysis, statistical processing and numerical theory predictions. The package offers many useful features, including complete flexibility and easy customization of input/output formats; efficient measurements of power spectrum, PDF, Minkowski functionals and peak counts of convergence maps; survey masks; artificial noise generation engines; easy to compute parameter statistical inferences; ray tracing simulations; and many others. It requires standard numpy and scipy, and depending on tools used, may require Astropy (ascl:1304.002), emcee (ascl:1303.002), matplotlib, and mpi4py.

  12. Foundations for a theory of gravitation theories

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.; Lee, D. L.; Lightman, A. P.

    1972-01-01

    A foundation is laid for future analyses of gravitation theories. This foundation is applicable to any theory formulated in terms of geometric objects defined on a 4-dimensional spacetime manifold. The foundation consists of (1) a glossary of fundamental concepts; (2) a theorem that delineates the overlap between Lagrangian-based theories and metric theories; (3) a conjecture (due to Schiff) that the Weak Equivalence Principle implies the Einstein Equivalence Principle; and (4) a plausibility argument supporting this conjecture for the special case of relativistic, Lagrangian-based theories.

  13. The Importance of Site Selection for Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Umar, Roslan; Zainal Abidin, Zamri; Abidin Ibrahim, Zainol

    2014-10-01

    Radio sources are very weak since this object travel very far from outer space. Radio astronomy studies are limited due to radio frequency interference (RFI) that is made by man. If the harassment is not stopped, it will provide critical problems in their radio astronomy scientists research. The purpose of this study is to provide RFI map Peninsular Malaysia with a minimum mapping techniques RFI interference. RFI mapping technique using GIS is proposed as a tool in mapping techniques. Decision-making process for the selection requires gathering information from a variety of parameters. These factors affecting the selection process are also taken account. In this study, various factors or parameters involved such as availability of telecommunications transmission (including radio and television), rainfall, water line and human activity. This study will benefit radio astronomy research especially in the RFI profile in Malaysia. Keywords: Radio Astronomy, Radio Frequency Interference (RFI), RFI mapping technique : GIS.

  14. The Future of Radio astronomy

    NASA Astrophysics Data System (ADS)

    Ekers, R. D.

    2001-12-01

    Five decades ago, astronomers finally broke free of the boundaries of light when a new science, radio astronomy, was born. This new way of "seeing" rapidly uncovered a range of unexpected objects in the cosmos. This was our first view of the non-thermal universe, and our first unobscured view of the universe. In its short life, radio astronomy has had an unequalled record of discovery, including four Nobel prizes: Big-Bang radiation, neutron stars, aperture synthesis and gravitational radiation. Radio telescopes have followed the pattern of exponential growth generally seen in flourishing areas of science and technology and there is no technical reason for this not to continue, but to do so will require a shift in technology that will set new challenges. New technologies have made it possible to construct an affordable radio telescope with collecting area of one square km the SKA. Such a telescope would be so powerful that we could expand our knowledge of the universe from the earliest stages of its formation through to planetary exploration with greatly enhanced spacecraft communications. The SKA will join the new generation of telescopes at other wavebands with the sensitivity and resolution to image the earliest phases of galaxy formation, as well as greatly extending the range of unique science accessible at radio wavelengths. We already know how to build an SKA, the issue is how to build the most cost effective SKA, and how to maximize the science we can do with it. The path we have chosen to achieve this vision is through international collaboration. Following the pattern of other successful international collaborations in science we have started this process early, and we are already benefiting from the level of innovation generated by our international interactions.

  15. Bayesian analysis on gravitational waves and exoplanets

    NASA Astrophysics Data System (ADS)

    Deng, Xihao

    constraints on the function space that may be reasonably thought to characterize the range of gravitational wave signals. For example, focus attention on the detection of a gravitational wave burst, by which we mean a signal that begins and ends over the course of an observational epoch. The burst may result from a source that we know how to model - e.g., a near-unity mass ratio black hole binary system - or it may be the result of a process, which we have not imagined and, so, have no model for. Similarly, a gravitational wave background resulting from a superposition of a number of weak sources may be difficult to characterize if the number of weak sources is sufficiently large that none can be individually resolved, but not so large that their superposition leads to a reasonably Gaussian distribution. The fourth part develops Bayesian analysis methods that can be used to detect gravitational waves generated from circular-orbit supermassive black hole binaries with a pulsar timing array. PTA response to such gravitational waves can be modeled as the difference between two sinusoidal terms --- the one with a coherent phase among different pulsars called "Earth term" and the other one with incoherent phases among different pulsars called "pulsar term". For gravitational waves from slowly evolving binaries, the two terms in the PTA response model have the same frequency. Previous methods aimed at detecting gravitational waves from circular-orbit binaries ignored pulsar terms in data analysis since those terms were considered to be negligible when averaging over all the pulsars. However, it is found that we can incorporate the contributions of pulsar terms into data analysis in the case of slowly evolving binaries by treating the incoherent phases in pulsar terms as unknown parameters to be marginalized. The final part of this thesis applies Bayesian analysis to search for the evidence of a planetary system around the K0 giant star HD 102103 detected by the Penn State

  16. DIFFUSIVE SHOCK ACCELERATION SIMULATIONS OF RADIO RELICS

    SciTech Connect

    Kang, Hyesung; Ryu, Dongsu; Jones, T. W. E-mail: ryu@canopus.cnu.ac.kr

    2012-09-01

    Recent radio observations have identified a class of structures, so-called radio relics, in clusters of galaxies. The radio emission from these sources is interpreted as synchrotron radiation from GeV electrons gyrating in {mu}G-level magnetic fields. Radio relics, located mostly in the outskirts of clusters, seem to associate with shock waves, especially those developed during mergers. In fact, they seem to be good structures to identify and probe such shocks in intracluster media (ICMs), provided we understand the electron acceleration and re-acceleration at those shocks. In this paper, we describe time-dependent simulations for diffusive shock acceleration at weak shocks that are expected to be found in ICMs. Freshly injected as well as pre-existing populations of cosmic-ray (CR) electrons are considered, and energy losses via synchrotron and inverse Compton are included. We then compare the synchrotron flux and spectral distributions estimated from the simulations with those in two well-observed radio relics in CIZA J2242.8+5301 and ZwCl0008.8+5215. Considering that CR electron injection is expected to be rather inefficient at weak shocks with Mach number M {approx}< a few, the existence of radio relics could indicate the pre-existing population of low-energy CR electrons in ICMs. The implication of our results on the merger shock scenario of radio relics is discussed.

  17. RADIO ALTIMETERS

    DOEpatents

    Bogle, R.W.

    1960-11-22

    A radio ranging device is described which utilizes a superregenerative oscillator having alternate sending and receiving phases with an intervening ranging interval between said phases, means for varying said ranging interval, means responsive to an on-range noise reduction condition for stopping said means for varying the ranging interval and indicating means coupled to the ranging interval varying means and calibrated in accordance with one-half the product of the ranging interval times the velocity of light whereby the range is indicated.

  18. The Parkes Pulsar Timing Array and detection of gravitational waves

    NASA Astrophysics Data System (ADS)

    Manchester, R.

    Gravitational waves are an important prediction of Einstein s general theory of relativity Evidence for their existence has come from observations of orbit decay in double-neutron-star binary systems but up to now despite huge efforts there has been no direct detection of these waves In collaboration with groups from the Swinburne University of Technology Melbourne and the University of Texas Brownsville we have embarked on a major project to establish the Parkes Pulsar Timing Array PPTA with the principal goal of making a direct detection of gravitational waves of astronomical origin The project involves making precision timing observations of 20 millisecond pulsars at intervals of 2 -- 3 weeks using the Parkes 64-m radio telescope Observations are made at three radio frequencies 685 1400 and 3100 MHz to allow correction for interstellar propagation effects The PPTA is most sensitive to gravitational waves with frequencies in the nanoHertz range and hence is complementary to ground- and space-based laser interferometer systems Simulations suggest that if timing precisions of order 100 nanoseconds can be reached for most of the observed sample over a 5-year data span the stochastic background of gravitational waves from super-massive binary black holes in the cores of galaxies should be detectable Currently we have achieved this level of precision for 3 or 4 pulsars and sub-microsecond precision for a further 8 or 9 pulsars Improved hardware and software systems under development will hopefully allow us to reach our goal The PPTA

  19. Analysis of the Capability and Limitations of Relativistic Gravity Measurements Using Radio Astronomy Methods

    NASA Technical Reports Server (NTRS)

    Shapiro, I. I.; Counselman, C. C., III

    1975-01-01

    The uses of radar observations of planets and very-long-baseline radio interferometric observations of extragalactic objects to test theories of gravitation are described in detail with special emphasis on sources of error. The accuracy achievable in these tests with data already obtained, can be summarized in terms of: retardation of signal propagation (radar), deflection of radio waves (interferometry), advance of planetary perihelia (radar), gravitational quadrupole moment of sun (radar), and time variation of gravitational constant (radar). The analyses completed to date have yielded no significant disagreement with the predictions of general relativity.

  20. Definition phase of Grand Tour missions/radio science investigations study for outer planets missions

    NASA Technical Reports Server (NTRS)

    Tyler, G. L.

    1972-01-01

    Scientific instrumentation for satellite communication and radio tracking systems in the outer planet exploration mission is discussed. Mission planning considers observations of planetary and satellite-masses, -atmospheres, -magnetic fields, -surfaces, -gravitational fields, solar wind composition, planetary radio emissions, and tests of general relativity in time delay and ray bending experiments.

  1. Gravitational mass of positron from LEP synchrotron losses

    DOE PAGESBeta

    Kalaydzhyan, Tigran

    2016-07-27

    General relativity(GR) is the current description of gravity in modern physics. One of the cornerstones of GR, as well as Newton’s theory of gravity, is the weak equivalence principle (WEP), stating that the trajectory of a freely falling test body is independent of its internal structure and composition. WEP is known to be valid for the normal matter with a high precision. However, due to the rarity of antimatter and weakness of the gravitational forces, the WEP has never been confirmed for antimatter. The current direct bounds on the ratio between the gravitational and inertial masses of the antihydrogen domore » not rule out a repulsive nature for the antimatter gravity. Here we establish an indirect bound of 0.13% on the difference between the gravitational and inertial masses of the positron (antielectron) from the analysis of synchrotron losses at the Large Electron-Positron collider (LEP). As a result, this serves as a confirmation of the conventional gravitational properties of antimatter without common assumptions such as, e.g., coupling of gravity to virtual particles, dynamics of distant astrophysical sources and the nature of absolute gravitational potentials.« less

  2. Gravitational mass of positron from LEP synchrotron losses

    PubMed Central

    Kalaydzhyan, Tigran

    2016-01-01

    General relativity(GR) is the current description of gravity in modern physics. One of the cornerstones of GR, as well as Newton’s theory of gravity, is the weak equivalence principle (WEP), stating that the trajectory of a freely falling test body is independent of its internal structure and composition. WEP is known to be valid for the normal matter with a high precision. However, due to the rarity of antimatter and weakness of the gravitational forces, the WEP has never been confirmed for antimatter. The current direct bounds on the ratio between the gravitational and inertial masses of the antihydrogen do not rule out a repulsive nature for the antimatter gravity. Here we establish an indirect bound of 0.13% on the difference between the gravitational and inertial masses of the positron (antielectron) from the analysis of synchrotron losses at the Large Electron-Positron collider (LEP). This serves as a confirmation of the conventional gravitational properties of antimatter without common assumptions such as, e.g., coupling of gravity to virtual particles, dynamics of distant astrophysical sources and the nature of absolute gravitational potentials. PMID:27461548

  3. Gravitational mass of positron from LEP synchrotron losses

    NASA Astrophysics Data System (ADS)

    Kalaydzhyan, Tigran

    2016-07-01

    General relativity(GR) is the current description of gravity in modern physics. One of the cornerstones of GR, as well as Newton’s theory of gravity, is the weak equivalence principle (WEP), stating that the trajectory of a freely falling test body is independent of its internal structure and composition. WEP is known to be valid for the normal matter with a high precision. However, due to the rarity of antimatter and weakness of the gravitational forces, the WEP has never been confirmed for antimatter. The current direct bounds on the ratio between the gravitational and inertial masses of the antihydrogen do not rule out a repulsive nature for the antimatter gravity. Here we establish an indirect bound of 0.13% on the difference between the gravitational and inertial masses of the positron (antielectron) from the analysis of synchrotron losses at the Large Electron-Positron collider (LEP). This serves as a confirmation of the conventional gravitational properties of antimatter without common assumptions such as, e.g., coupling of gravity to virtual particles, dynamics of distant astrophysical sources and the nature of absolute gravitational potentials.

  4. Gravitational mass of positron from LEP synchrotron losses.

    PubMed

    Kalaydzhyan, Tigran

    2016-07-27

    General relativity(GR) is the current description of gravity in modern physics. One of the cornerstones of GR, as well as Newton's theory of gravity, is the weak equivalence principle (WEP), stating that the trajectory of a freely falling test body is independent of its internal structure and composition. WEP is known to be valid for the normal matter with a high precision. However, due to the rarity of antimatter and weakness of the gravitational forces, the WEP has never been confirmed for antimatter. The current direct bounds on the ratio between the gravitational and inertial masses of the antihydrogen do not rule out a repulsive nature for the antimatter gravity. Here we establish an indirect bound of 0.13% on the difference between the gravitational and inertial masses of the positron (antielectron) from the analysis of synchrotron losses at the Large Electron-Positron collider (LEP). This serves as a confirmation of the conventional gravitational properties of antimatter without common assumptions such as, e.g., coupling of gravity to virtual particles, dynamics of distant astrophysical sources and the nature of absolute gravitational potentials.

  5. Gravitational mass of positron from LEP synchrotron losses.

    PubMed

    Kalaydzhyan, Tigran

    2016-01-01

    General relativity(GR) is the current description of gravity in modern physics. One of the cornerstones of GR, as well as Newton's theory of gravity, is the weak equivalence principle (WEP), stating that the trajectory of a freely falling test body is independent of its internal structure and composition. WEP is known to be valid for the normal matter with a high precision. However, due to the rarity of antimatter and weakness of the gravitational forces, the WEP has never been confirmed for antimatter. The current direct bounds on the ratio between the gravitational and inertial masses of the antihydrogen do not rule out a repulsive nature for the antimatter gravity. Here we establish an indirect bound of 0.13% on the difference between the gravitational and inertial masses of the positron (antielectron) from the analysis of synchrotron losses at the Large Electron-Positron collider (LEP). This serves as a confirmation of the conventional gravitational properties of antimatter without common assumptions such as, e.g., coupling of gravity to virtual particles, dynamics of distant astrophysical sources and the nature of absolute gravitational potentials. PMID:27461548

  6. Weak cosmic censorship: as strong as ever.

    PubMed

    Hod, Shahar

    2008-03-28

    Spacetime singularities that arise in gravitational collapse are always hidden inside of black holes. This is the essence of the weak cosmic censorship conjecture. The hypothesis, put forward by Penrose 40 years ago, is still one of the most important open questions in general relativity. In this Letter, we reanalyze extreme situations which have been considered as counterexamples to the weak cosmic censorship conjecture. In particular, we consider the absorption of scalar particles with large angular momentum by a black hole. Ignoring back reaction effects may lead one to conclude that the incident wave may overspin the black hole, thereby exposing its inner singularity to distant observers. However, we show that when back reaction effects are properly taken into account, the stability of the black-hole event horizon is irrefutable. We therefore conclude that cosmic censorship is actually respected in this type of gedanken experiments.

  7. Weak cosmic censorship: as strong as ever.

    PubMed

    Hod, Shahar

    2008-03-28

    Spacetime singularities that arise in gravitational collapse are always hidden inside of black holes. This is the essence of the weak cosmic censorship conjecture. The hypothesis, put forward by Penrose 40 years ago, is still one of the most important open questions in general relativity. In this Letter, we reanalyze extreme situations which have been considered as counterexamples to the weak cosmic censorship conjecture. In particular, we consider the absorption of scalar particles with large angular momentum by a black hole. Ignoring back reaction effects may lead one to conclude that the incident wave may overspin the black hole, thereby exposing its inner singularity to distant observers. However, we show that when back reaction effects are properly taken into account, the stability of the black-hole event horizon is irrefutable. We therefore conclude that cosmic censorship is actually respected in this type of gedanken experiments. PMID:18517851

  8. Weak Cosmic Censorship: As Strong as Ever

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2008-03-01

    Spacetime singularities that arise in gravitational collapse are always hidden inside of black holes. This is the essence of the weak cosmic censorship conjecture. The hypothesis, put forward by Penrose 40 years ago, is still one of the most important open questions in general relativity. In this Letter, we reanalyze extreme situations which have been considered as counterexamples to the weak cosmic censorship conjecture. In particular, we consider the absorption of scalar particles with large angular momentum by a black hole. Ignoring back reaction effects may lead one to conclude that the incident wave may overspin the black hole, thereby exposing its inner singularity to distant observers. However, we show that when back reaction effects are properly taken into account, the stability of the black-hole event horizon is irrefutable. We therefore conclude that cosmic censorship is actually respected in this type of gedanken experiments.

  9. Spacecraft Radio Scintillation and Solar System Exploration

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    1993-01-01

    When a wave propagates through a turbulent medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena that have been the subject of extensive study. The observed scattering effects include amplitude or intensity scintillation, phase scintillation, angular broadening, and spectral broadening, among others. In this paper, I will refer to these scattering effects collectively as scintillation. Although the most familiar example is probably the twinkling of stars (light wave intensity scintillation by turbulence in the Earth's atmosphere), scintillation has been encountered and investigated in such diverse fields as ionospheric physics, oceanography, radio astronomy, and radio and optical communications. Ever since planetary spacecraft began exploring the solar system, scintillation has appeared during the propagation of spacecraft radio signals through planetary atmospheres, planetary ionospheres, and the solar wind. Early studies of these phenomena were motivated by the potential adverse effects on communications and navigation, and on experiments that use the radio link to conduct scientific investigations. Examples of the latter are radio occultation measurements (described below) of planetary atmospheres to deduce temperature profiles, and the search for gravitational waves. However,these concerns soon gave way to the emergence of spacecraft radio scintillation as a new scientific tool for exploring small-scale dynamics in planetary atmospheres and structure in the solar wind, complementing in situ and other remote sensing spacecraft measurements, as well as scintillation measurements using natural (celestial) radio sources. The purpose of this paper is to briefly describe and review the solar system spacecraft radio scintillation observations, to summarize the salient features of wave propagation analyses employed in interpreting them, to underscore the unique remote sensing capabilities and scientific relevance of

  10. Gravitational Microlensing by the Ellis Wormhole

    NASA Astrophysics Data System (ADS)

    Abe, F.

    2010-12-01

    A method to calculate light curves of the gravitational microlensing of the Ellis wormhole is derived in the weak-field limit. In this limit, lensing by the wormhole produces one image outside the Einstein ring and another image inside. The weak-field hypothesis is a good approximation in Galactic lensing if the throat radius is less than 1011 km. The light curves calculated have gutters of approximately 4% immediately outside the Einstein ring crossing times. The magnification of the Ellis wormhole lensing is generally less than that of Schwarzschild lensing. The optical depths and event rates are calculated for the Galactic bulge and Large Magellanic Cloud fields according to bound and unbound hypotheses. If the wormholes have throat radii between 100 and 107 km, are bound to the galaxy, and have a number density that is approximately that of ordinary stars, detection can be achieved by reanalyzing past data. If the wormholes are unbound, detection using past data is impossible.

  11. Modeling a nonperturbative spinor vacuum interacting with a strong gravitational wave

    NASA Astrophysics Data System (ADS)

    Dzhunushaliev, Vladimir; Folomeev, Vladimir

    2015-07-01

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

  12. Radio Jove: Jupiter Radio Astronomy for Citizens

    NASA Astrophysics Data System (ADS)

    Higgins, Charles; Thieman, J. R.; Flagg, R.; Reyes, F. J.; Sky, J.; Greenman, W.; Brown, J.; Typinski, D.; Ashcraft, T.; Mount, A.

    2014-01-01

    Radio JOVE is a hands-on educational activity that brings the radio sounds of the Sun, Jupiter, the Milky Way Galaxy, and terrestrial radio noise to students, teachers, and the general public. Participants may build a simple radio telescope kit, make scientific observations, and interact with professional radio observatories in real-time over the Internet. Our website (http://radiojove.gsfc.nasa.gov) includes science information, construction manuals, observing guides, and education resources for teachers and students. Radio Jove is continually expanding its participants with over 1800 kits sold to more than 70 countries worldwide. Recently some of our most dedicated observers have upgraded their Radio Jove antennas to semi-professional observatories. We have spectrographs and wide band antennas, some with 8 MHz bandwidth and some with dual polarization capabilities. In an effort to add to the science literature, these observers are coordinating their efforts to pursue some basic questions about Jupiter’s radio emissions (radio source locations, spectral structure, long term changes, etc.). We can compare signal and ionosphere variations using the many Radio Jove observers at different locations. Observers are also working with members of the Long Wavelength Array Station 1 (LWA1) radio telescope to coordinate observations of Jupiter; Radio Jove is planning to make coordinated observations while the Juno Mission is active beginning in 2015. The Radio Jove program is overviewed, its hardware and software are highlighted, recent sample observations are shown, and we demonstrate that we are capable of real citizen science.

  13. Dumbbell galaxies and precessing radio jets

    NASA Astrophysics Data System (ADS)

    Wirth, A.; Smarr, L.; Gallagher, J. S.

    1982-04-01

    It is suggested that a subclass of inversion-symmetric distorted extended radio sources (Z-shapes) have shapes produced by effects on large scales compared with the central engine. The subclass is defined by those sources whose underlying galaxies have a dumbbell or multiple nuclei optical morphology. New optical observations are presented which indicate that in one well-studied Z-shape source, NGC 326, there are two galaxies passing at a projected distance of about 10 kpc and that the gravitational coupling of the nonradio galaxy on the radio galaxy's atmosphere may be the mechanism which has realigned the jet direction. If the proposed interpretation is correct, some large-scale jet properties of double radio sources reveal more about properties of the gas distribution in galaxies and less about the central engine than heretofore supposed.

  14. Quantum gravitational decoherence of light and matter

    NASA Astrophysics Data System (ADS)

    Oniga, Teodora; Wang, Charles H.-T.

    2016-02-01

    Real world quantum systems are open to perpetual influence from the wider environment. Quantum gravitational fluctuations provide a most fundamental source of the environmental influence through their universal interactions with all forms of energy and matter causing decoherence. This may have subtle implications on precision laboratory experiments and astronomical observations and could limit the ultimate capacities for quantum technologies prone to decoherence. To establish the essential physical mechanism of decoherence under weak spacetime fluctuations, we carry out a sequence of analytical steps utilizing the Dirac constraint quantization and gauge invariant influence functional techniques resulting in a general master equation of a compact form that describes an open quantum gravitational system with arbitrary bosonic fields. An initial application of the theory is illustrated by the implied quantum gravitational dissipation of light as well as (non)relativistic massive or massless scalar particles. Related effects could eventually lead to important physical consequences including those on a cosmological scale and for a large number of correlated particles.

  15. Gravitational mass of relativistic matter and antimatter

    NASA Astrophysics Data System (ADS)

    Kalaydzhyan, Tigran

    2015-12-01

    The universality of free fall, the weak equivalence principle (WEP), is a cornerstone of the general theory of relativity, the most precise theory of gravity confirmed in all experiments up to date. The WEP states the equivalence of the inertial, m, and gravitational, mg, masses and was tested in numerous occasions with normal matter at relatively low energies. However, there is no confirmation for the matter and antimatter at high energies. For the antimatter the situation is even less clear - current direct observations of trapped antihydrogen suggest the limits - 65 gravitational mass of relativistic electrons and positrons coming from the absence of the vacuum Cherenkov radiation at the Large Electron-Positron Collider (LEP) and stability of photons at the Tevatron collider in presence of the annual variations of the solar gravitational potential. Our result clearly rules out the speculated antigravity. By considering the absolute potential of the Local Supercluster (LS), we also predict the bounds 1 - 4 ×10-7

  16. The gravitational analog of Faraday's induction law

    NASA Astrophysics Data System (ADS)

    Zile, Daniel; Overduin, James

    2015-04-01

    Michael Faraday, the discoverer of electromagnetic induction, was convinced that there must also be a gravitational analog of this law, and he carried out drop-tower experiments in 1849 to look for the electric current induced in a coil by changes in gravitational flux through the coil. This work, now little remembered, was in some ways the first investigation of what we would now call a unified-field theory. We revisit Faraday's experiments in the light of current knowledge and ask what might be learned if they were to be performed today. We then review the gravitational analog for Faraday's law that arises within the vector (or gravito-electromagnetic) approximation to Einstein's theory of general relativity in the weak-field, low-velocity limit. This law relates spinning masses and induced ``mass currents'' rather than spinning charges and electric currents, but is otherwise remarkably similar to its electromagnetic counterpart. The predicted effects are completely unobservable in everyday settings like those envisioned by Faraday, but are thought to be relevant in astrophysical contexts like the accretion disks around collapsed stars, thus bearing out Faraday's remarkable intuition. Undergraduate student.

  17. 21 centimeter HI absorption at z = 0. 437 against the extended radio structure of 3c 196

    SciTech Connect

    Brown, R.L.; Mitchell, K.J.

    1983-01-01

    We report the detection of an absorption line at 988.7. MHz toward the quasar 3C 196. We identify this line as the lambda21 cm line of neutral atomic hydrogen seen at a redshift of z/sub abs/ = 0.4366. No optical absorption lines have been noted in the z/sub em/ = 0.871 quasar 3C 196 heretofore. All the radio emission of 3C 196 is contained in two thetaroughly-equal3'' extended lobes symmetrically placed (position angle approx.26/sup 0/) about the optical object. The optical QSO itself is an extremely weak, <1 mJy, radio source. Thus to account for the approx.0.5 Jy seen in the absorption line we infer that the diameter of the absorbing region must be at least as large as 750 pc and perhaps as large as, or larger than, 30 kpc. We note further than an optical wisp is seen extending approx.3'' x 1'' from the QSO at position angle approx.120/sup 0/, that is in a direction perpendicular to the separation of the radio lobes. If this wisp is the disk of an intervening galaxy, then the H i absorption is direct evidence for absorption in a galactic halo. Puzzles abound; (1) If the optical wisp seen superposed on the QSO is an intervening galaxy then what aspects, if any, of the emission from 3C 196 are gravitational lens effects. (2) If the wisp is associated with the QSO, why is it radio quiet and why is it orthogonal to the extended radio structure of 3C 196. (3) Is it significant that z/sub abs/ is one-half z/sub em/ within the errors.

  18. Gravitational lensing by gravastars

    NASA Astrophysics Data System (ADS)

    Kubo, Tomohiro; Sakai, Nobuyuki

    2016-04-01

    As a possible method to detect gravastars (gravitational-vacuum-star), which was originally proposed by Mazur and Mottola, we study their gravitational lensing effects. Specifically, we adopt a spherical thin-shell model of a gravastar developed by Visser and Wiltshire, which connects interior de Sitter geometry and exterior Schwarzschild geometry, and assume that its surface is optically transparent. We calculate the image of a companion which rotates around the gravastar; we find that some characteristic images appear, depending on whether the gravastar possess unstable circular orbits of photons (Model 1) or not (Model 2). For Model 2, we calculate the total luminosity change, which is called microlensing effects; the maximal luminosity could be considerably larger than the black hole with the same mass.

  19. Gravitational coset models

    NASA Astrophysics Data System (ADS)

    Cook, Paul P.; Fleming, Michael

    2014-07-01

    The algebra A {/D - 3 + + +} dimensionally reduces to the E D-1 symmetry algebra of (12 - D)-dimensional supergravity. An infinite set of five-dimensional gravitational objects embedded in D-dimensions is constructed by identifying the null geodesic motion on cosets embedded in the generalised Kac-Moody algebra A {/D - 3 + + +}. By analogy with super-gravity these are bound states of dual gravitons. The metric interpolates continuously between exotic gravitational solutions generated by the action of an affine sub-group. We investigate mixed-symmetry fields in the brane sigma model, identify actions for the full interpolating bound state and investigate the dualisation of the bound state to a solution of the Einstein-Hilbert action via the Hodge dual on multiforms. We conclude that the Hodge dual is insufficient to reconstruct solutions to the Einstein-Hilbert action from mixed-symmetry tensors.

  20. Applications of gravitational lensing

    NASA Astrophysics Data System (ADS)

    Dalal, Neal

    I derive the basic principles of gravitational lensing, and proceed to describe several astrophysical applications. First, invariants in gravitational lensing magnification are derived using techniques of multidimensional residue calculus, and illustrated with example calculations. Then I discuss how these invariant quantities may be useful for measuring the properties of lenses. Next, I discuss the use of astrometric microlensing for studying extrasolar planets. Finally, the use of lensing for the study of substructure in dark matter halos is presented, along with ramifications for the small-scale power spectrum of matter fluctuations. The strongest bounds to date are placed on the mass of the dark matter particle, as well as bounds on the neutrino mass and slope of the primordial power spectrum.

  1. Self-gravitating skyrmions

    NASA Astrophysics Data System (ADS)

    Ayón-Beato, Eloy; Canfora, Fabrizio; Zanelli, Jorge

    2016-05-01

    A self-gravitating Skyrmion is an analytic and globally regular solution of the Einstein-Skyrme system with nonvanishing topological charge. The spacetime is the direct product R × S3 and the Skyrmion is the self-gravitating generalization of the static hedgehog solution of Manton and Ruback. This solution can be promoted to a dynamical one in which the spacetime is a cosmology of the Bianchi type-IX and, through an analytic continuation, it can also be turned into a transversable asymptotically AdS Lorentzian wormhole. The stress-energy of this wormhole satisfies physically realistic energy conditions and the only “exotic matter” required by it is a negative cosmological constant.

  2. Linked Gravitational Radiation

    NASA Astrophysics Data System (ADS)

    Thompson, Amy; Swearngin, Joseph; Wickes, Alexander; Willem Dalhuisen, Jan; Bouwmeester, Dirk

    2013-04-01

    The electromagnetic knot is a topologically nontrivial solution to the vacuum Maxwell equations with the property that any two field lines belonging to either the electric, magnetic, or Poynting vector fields are closed and linked exactly once [1]. The relationship between the vacuum Maxwell and linearized Einstein equations, as expressed in the form of the spin-N massless field equations, suggests that gravitational radiation possesses analogous topologically nontrivial field configurations. Using twistor methods we find the analogous spin-2 solutions of Petrov types N, D, and III. Aided by the concept of tendex and vortex lines as recently developed for the physical interpretation of solutions in general relativity [2], we investigate the physical properties of these knotted gravitational fields by characterizing the topology of their associated tendex and vortex lines.[4pt] [1] Ranada, A. F. and Trueba, J. L., Mod. Nonlinear Opt. III, 119, 197 (2002).[2] Nichols, D. A., et al., Phys. Rev. D, 84 (2011).

  3. Gravitationally induced quantum transitions

    NASA Astrophysics Data System (ADS)

    Landry, A.; Paranjape, M. B.

    2016-06-01

    In this paper, we calculate the probability for resonantly inducing transitions in quantum states due to time-dependent gravitational perturbations. Contrary to common wisdom, the probability of inducing transitions is not infinitesimally small. We consider a system of ultracold neutrons, which are organized according to the energy levels of the Schrödinger equation in the presence of the Earth's gravitational field. Transitions between energy levels are induced by an oscillating driving force of frequency ω . The driving force is created by oscillating a macroscopic mass in the neighborhood of the system of neutrons. The neutron lifetime is approximately 880 sec while the probability of transitions increases as t2. Hence, the optimal strategy is to drive the system for two lifetimes. The transition amplitude then is of the order of 1.06 ×10-5, and hence with a million ultracold neutrons, one should be able to observe transitions.

  4. Gravitational wave astronomy.

    NASA Astrophysics Data System (ADS)

    Finn, L. S.

    Astronomers rely on a multiplicity of observational perspectives in order to infer the nature of the Universe. Progress in astronomy has historically been associated with new or improved observational perspectives. Gravitational wave detectors now under construction will provide us with a perspective on the Universe fundamentally different from any we have come to know. With this new perspective comes the hope of new insights and understanding, not just of exotic astrophysical processes, but of "bread-and-butter" astrophysics: e.g., stars and stellar evolution, galaxy formation and evolution, neutron star structure, and cosmology. In this report the author discusses briefly a small subset of the areas of conventional, "bread-and-butter" astrophysics where we can reasonably hope that gravitational wave observations will provide us with valuable new insights and understandings.

  5. Spacetime and gravitation.

    NASA Astrophysics Data System (ADS)

    Kopczyński, W.; Trautman, A.

    This book is a revised translation of the Polish original "Czasoprzestrzeń i grawitacja", Warszawa (Poland), Państwowe Wydawnictwo Naukowe, 1984. Ideas about space and time are at the root of one's understanding of nature, both at the intuitive level of everyday experience and in the framework of sophisticated physical theories. These ideas have led to the development of geometry and its applications to physics. The contemporary physical theory of space and time, including its extention to the phenomena of gravitation, is Einstein's theory of relativity. The book is a short introduction to this theory. A great deal of emphasis is given to the geometrical aspects of relativity theory and its comparison with the Newtonian view of the world. There are short chapters on the origins of Einstein's theory, gravitational waves, cosmology, spinors and the Einstein-Cartan theory.

  6. Four Poission-Laplace Theory of Gravitation (I)

    NASA Astrophysics Data System (ADS)

    Nyambuya, Golden Gadzirayi

    2015-08-01

    The Poisson-Laplace equation is a working and acceptable equation of gravitation which is mostly used or applied in its differential form in Magneto-Hydro-Dynamic (MHD) modelling of e.g. molecular clouds. From a general relativistic standpoint, it describes gravitational fields in the region of low spacetime curvature as it emerges in the weak field limit. For non-static gravitational fields, this equation is not generally covariant. On the requirements of general covariance, this equation can be extended to include a time-dependent component, in which case one is led to the Four Poisson-Laplace equation. We solve the Four Poisson-Laplace equation for radial solutions, and apart from the Newtonian gravitational component, we obtain four new solutions leading to four new gravitational components capable (in-principle) of explaining e.g. the Pioneer anomaly, the Titius-Bode Law and the formation of planetary rings. In this letter, we focus only on writing down these solutions. The task showing that these new solutions might explain the aforesaid gravitational anomalies has been left for separate future readings.

  7. Learning radio astronomy by doing radio astronomy

    NASA Astrophysics Data System (ADS)

    Vaquerizo Gallego, J. A.

    2011-11-01

    PARTNeR (Proyecto Académico con el Radio Telescopio de NASA en Robledo, Academic Project with the NASA Radio Telescope at Robledo) is an educational program that allows high school and undergraduate students to control a 34 meter radio telescope and conduct radio astronomical observations via the internet. High-school teachers who join the project take a course to learn about the science of radio astronomy and how to use the antenna as an educational resource. Also, teachers are provided with learning activities they can do with their students and focused on the classroom implementation of the project within an interdisciplinary framework. PARTNeR provides students with firsthand experience in radio astronomy science. Thus, remote radio astronomical observations allow students to learn with a first rate scientific equipment the basics of radio astronomy research, aiming to arouse scientific careers and positive attitudes toward science. In this contribution we show the current observational programs and some recent results.

  8. Undulator Gravitational Deflection

    SciTech Connect

    Bowden, G.

    2005-01-31

    This note estimates distortions imposed by gravity on LCLS undulator strong-backs. Because of the strongback's asymmetric cross section, gravitational forces cause both torsion as well as simple bending. The superposition of these two effects yields a 4.4 {micro}m maximum deflection and a 0.16 milli radian rotation of the undulator axis. The choice of titanium is compared to aluminum.

  9. Kolmogorov-Zakharov spectrum in AdS gravitational collapse.

    PubMed

    de Oliveira, H P; Pando Zayas, Leopoldo A; Rodrigues, E L

    2013-08-01

    We study black hole formation during the gravitational collapse of a massless scalar field in asymptotically D-dimensional anti-de Sitter AdS(D) spacetimes for D = 4, 5. We conclude that spherically symmetric gravitational collapse in asymptotically AdS spaces is turbulent and characterized by a Kolmogorov-Zakharov spectrum. Namely, we find that after an initial period of weakly nonlinear evolution, there is a regime where the power spectrum of the Ricci scalar evolves as ω(-s) with the frequency, ω, and s ≈ 1.7 ± 0.1.

  10. The generation of gravitational waves. II - The postlinear formalism revisited

    NASA Technical Reports Server (NTRS)

    Crowley, R. J.; Thorne, K. S.

    1977-01-01

    Two different versions of the Green's function for the scalar wave equation in weakly curved spacetime (one due to DeWitt and DeWitt, the other to Thorne and Kovacs) are compared and contrasted; and their mathematical equivalence is demonstrated. Then the DeWitt-DeWitt Green's function is used to construct several alternative versions of the Thorne-Kovacs postlinear formalism for gravitational-wave generation. Finally it is shown that, in calculations of gravitational bremsstrahlung radiation, some of our versions of the postlinear formalism allow one to treat the interacting bodies as point masses, while others do not.

  11. General relativistic theory of light propagation in the field of gravitational multipoles

    NASA Astrophysics Data System (ADS)

    Korobkov, Pavel

    We consider propagation of electromagnetic signals through the time-dependent gravitational field of an isolated astronomical system emitting gravitational waves. The system is assumed to possess multipole moments of arbitrary order. Working in the linear, weak-field approximation of general relativity, we obtain analytical expressions for light-ray trajectory and observable effects of bending of light, time delay, and gravitational rotation of the polarization plane. The relative positions of the source of light, the isolated system, and the observer are not restricted, which makes our formalism quite general and applicable for most practical situations. Asymptotic expressions for observable effects are obtained in two limiting cases of arrangement of light source, observer, and the source of gravitational waves: the gravitational-lens approximation and the approximation of plane gravitational waves. It is shown that in the gravitational-lens approximation the leading contributions to the effects due to multipole moments of arbitrary order fall off with the impact parameter as 1/d2 and 1/d3 for time delay and deflection of light respectively. Such, stronger than it could be a priori expected, dependance on impact parameter hinders observation of time-dependent effects in gravitational lensing. In the plane-gravitational-wave approximation the expressions for observable effects due to gravitational waves of arbitrary multipolarity are obtained in terms of the transverse-traceless (TT) part of the spacial components of the metric tensor.

  12. Impact of Gravitational Variations on Aging

    NASA Astrophysics Data System (ADS)

    Goradia, Shantilal

    2006-04-01

    Einstein's 1919 removal of the cosmological constant as a consequence of his analysis suggests a synonymy between gravitation and nuclear force, which is complimentary and supplementary to my suggestion of the synonymy between nuclear force and gravitation supporting the inflationary universe in version 2 of http://www.arXiv.org/physics/0210040 and vice versa. In version 1 of the same article, I am going a step deeper to suggest that all coupling constants are increasing with time consistent with Dirac's LNH and an observation that the universal constant of gravity is decreasing with time. The variations of coupling constants must inevitably impact the binding energy of organic particles resulting in an impact on the chemical energy output of the power plants of biological cells (DNA of Mitochondria). The web site http://home.comcast.net/ ˜ neardeath/science/001/pages/28.htm'' suggests a link between such energy outputs and aging. If the changes in the chemical energy output can be compensated by some means, it may be possible to reverse the aging process. This makes it important to establish weather the universal constant of gravity is changing as once reported. Gravity cannot be discounted as weak as done in the past, because the coupling constants it generates are not weak, nor fixed.

  13. Electromagnetic Counterparts of Gravitational Wave Sources: Mergers of Compact Objects

    NASA Astrophysics Data System (ADS)

    Kamble, Atish; Kaplan, David L. A.

    2013-01-01

    Mergers of compact objects are considered prime sources of gravitational waves (GW) and will soon be targets of GW observatories such as the Advanced-LIGO and VIRGO. Finding electromagnetic counterparts of these GW sources will be important to understand their nature. We discuss possible electromagnetic signatures of the mergers. We show that the BH-BH mergers could have luminosities which exceed Eddington luminosity from unity to several orders of magnitude depending on the masses of the merging BHs. As a result these mergers could be explosive, release up to 1051 erg of energy and shine as radio transients. At any given time we expect about a few such transients in the sky at GHz frequencies, which could be detected to be about 300 Mpc. It has also been argued that these radio transients would look alike radio supernovae with comparable detection rates. Multi-band follow-up could, however, distinguish between the mergers and supernovae.

  14. Observing cosmic string loops with gravitational lensing surveys

    SciTech Connect

    Mack, Katherine J.; Wesley, Daniel H.; King, Lindsay J.

    2007-12-15

    We show that the existence of cosmic strings can be strongly constrained by the next generation of gravitational lensing surveys at radio frequencies. We focus on cosmic string loops, which simulations suggest would be far more numerous than long (horizon-sized) strings. Using simple models of the loop population and minimal assumptions about the lensing cross section per loop, we estimate the optical depth to lensing and show that extant radio surveys such as CLASS have already ruled out a portion of the cosmic string model parameter space. Future radio interferometers, such as LOFAR and especially SKA, may constrain G{mu}/c{sup 2}<10{sup -9} in some regions of parameter space, outperforming current constraints from pulsar timing and the cosmic microwave backgound by up to two orders of magnitude. This method relies on direct detections of cosmic strings, and so is less sensitive to the theoretical uncertainties in string network evolution that weaken other constraints.

  15. Weak measure expansive flows

    NASA Astrophysics Data System (ADS)

    Lee, Keonhee; Oh, Jumi

    2016-01-01

    A notion of measure expansivity for flows was introduced by Carrasco-Olivera and Morales in [3] as a generalization of expansivity, and they proved that there were no measure expansive flows on closed surfaces. In this paper we introduce a concept of weak measure expansivity for flows which is really weaker than that of measure expansivity, and show that there is a weak measure expansive flow on a closed surface. Moreover we show that any C1 stably weak measure expansive flow on a C∞ closed manifold M is Ω-stable, and any C1 stably measure expansive flow on M satisfies both Axiom A and the quasi-transversality condition.

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

    SciTech Connect

    Demorest, P. B.; Ransom, S.; Ferdman, R. D.; Kaspi, V. M.; Gonzalez, M. E.; Stairs, I. H.; Nice, D.; Arzoumanian, Z.; Brazier, A.; Cordes, J. M.; Burke-Spolaor, S.; Lazio, J.; Chamberlin, S. J.; Ellis, J.; Giampanis, S.; Finn, L. S.; Freire, P.; Jenet, F.; Lommen, A. N.; McLaughlin, M.; and others

    2013-01-10

    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.

  17. Lunar Farside Radio Lab

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2005-03-01

    It is proposed that the Farside of the Moon should be protected legally against man-made radio pollution and uncontrolled exploitation. In fact, only by establishing a radiotelescope on the Farside of the Moon it will finally be possible to cope with the Radio Frequency Interference (RFI) that is now increasingly plaguing all of Radioastronomy, Bioastronomy and Search for Extraterrestrial Intelligence (SETI) Searches done from the surface of the Earth. It is suggested to partition the Farside into 3 sectors, each 60°wide, to ensurethe creation of a future “Lunar Farside Radio Lab” inside crater Daedalus (at 180°E) with our planned Radiotelescope (in practice a Phased Array),complete freedom to exploit the Nearside as well as the four Lagrangian points L1, L3, L4 and L5 of the Earth Moon system by allowing even some International Space Stations to be located there. It is also claimed, however, thatthe “opposite” Lagrangian point L2 should possibly be kept free of spacecrafts that would flood the Farside by the RFI they produce. Realistically, it might be difficult to comply with the latter request in view of the far-future development of a Space Base located there in order to depart towards the Asteroids and the Outer Planets at very reduced fuel consumption. A more reasonable request about any future space station located at the Earth Moon L2 point is thus that this future space station should be shielded to prevent its RFI from reaching the Farside of the Moon.A number of further astrophysical, astronautical and technical issues could just be highlighted in this study and deserve much more elaboration. To mention a few:the precise size of the “Quiet Cone” extending into space above the Farside of the Moon. Also, the experimental measurement of how quiet this Cone actually is by letting a radiometer orbit the Moon (see the web site www.rli.it);the mathematical modelling of the weak ionosphere of the Moon and its possible diffraction effects at very

  18. Observation of local radio emission associated with type III radio bursts and Langmuir waves

    NASA Technical Reports Server (NTRS)

    Reiner, M. J.; Stone, R. G.; Fainberg, J.

    1992-01-01

    The first clear detection of fundamental and harmonic radiation from the type III radio source region is presented. This radiation is characterized by its lack of frequency drift, its short rise and decay times, its relative weakness compared to the remotely observed radiation and its temporal coincidence with observed Langmuir waves. The observations were made with the radio and plasma frequency (URAP) receivers on the Ulysses spacecraft between about 1 and 2 AU from the Sun.

  19. Gravitational lensing by rotating naked singularities

    SciTech Connect

    Gyulchev, Galin N.; Yazadjiev, Stoytcho S.

    2008-10-15

    We model massive compact objects in galactic nuclei as stationary, axially symmetric naked singularities in the Einstein-massless scalar field theory and study the resulting gravitational lensing. In the weak deflection limit we study analytically the position of the two weak field images, the corresponding signed and absolute magnifications as well as the centroid up to post-Newtonian order. We show that there are static post-Newtonian corrections to the signed magnification and their sum as well as to the critical curves, which are functions of the scalar charge. The shift of the critical curves as a function of the lens angular momentum is found, and it is shown that they decrease slightly for the weakly naked and vastly for the strongly naked singularities with the increase of the scalar charge. The pointlike caustics drift away from the optical axis and do not depend on the scalar charge. In the strong deflection limit approximation, we compute numerically the position of the relativistic images and their separability for weakly naked singularities. All of the lensing quantities are compared to particular cases as Schwarzschild and Kerr black holes as well as Janis-Newman-Winicour naked singularities.

  20. The Deep Space Network: An instrument for radio science research

    NASA Technical Reports Server (NTRS)

    Renzetti, N. A.

    1981-01-01

    Doppler and ranging data routinely generated at the Deep Space Stations of the California Institute of Technology-Jet Propulsion Laboratory Deep Space Network serve as an excellent source of radio science information. Important radio science experiments based on Deep Space Network generated radio metric data have included confirmation of Einstein's Theory of Relativity, measurement of the masses and gravitational harmonics of the planets out to Saturn, and measurement of electron density distribution and turbulence in the solar corona. In response to an increased level of radio science requirements, the Deep Space Network chose in 1976 to implement a new radio science system, which was completed in late 1978. Key features include (1) highly phase stable open loop receivers, (2) reduction of recorded data bandwidth through use of programmed local oscillators, and (3) real time digitization and recording on computer compatible tape.

  1. Quantum Emulation of Gravitational Waves

    PubMed Central

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

    2015-01-01

    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. PMID:26169801

  2. Quantum Emulation of Gravitational Waves

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  3. Quantum Emulation of Gravitational Waves.

    PubMed

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

    2015-07-14

    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.

  4. Quantum Emulation of Gravitational Waves.

    PubMed

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

    2015-01-01

    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. PMID:26169801

  5. Solar-System Tests of Gravitational Theories

    NASA Technical Reports Server (NTRS)

    Shapiro, Irwin

    1997-01-01

    We are engaged in testing gravitational theory by means of observations of objects in the solar system. These tests include an examination of the Principle Of Equivalence (POE), the Shapiro delay, the advances of planetary perihelia, the possibility of a secular variation G in the "gravitational constant" G, and the rate of the de Sitter (geodetic) precession of the Earth-Moon system. These results are consistent with our preliminary results focusing on the contribution of Lunar Laser Ranging (LLR), which were presented at the seventh Marcel Grossmann meeting on general relativity. The largest improvement over previous results comes in the uncertainty for (eta): a factor of five better than our previous value. This improvement reflects the increasing strength of the LLR data. A similar analysis presented at the same meeting by a group at the Jet Propulsion Laboratory gave a similar result for (eta). Our value for (beta) represents our first such result determined simultaneously with the solar quadrupole moment from the dynamical data set. These results are being prepared for publication. We have shown how positions determined from different planetary ephemerides can be compared and how the combination of VLBI and pulse timing information can yield a direct tie between planetary and radio frames. We have continued to include new data in our analysis as they became available. Finally, we have made improvement in our analysis software (PEP) and ported it to a network of modern workstations from its former home on a "mainframe" computer.

  6. Gravitational collapse of Vaidya spacetime

    NASA Astrophysics Data System (ADS)

    Vertogradov, Vitalii

    2016-03-01

    The gravitational collapse of generalized Vaidya spacetime is considered. It is known that the endstate of gravitational collapse, as to whether a black hole or a naked singularity is formed, depends on the mass function M(v,r). Here we give conditions for the mass function which corresponds to the equation of the state P = αρ where α ∈ (0, 1 3] and according to these conditions we obtain either a black hole or a naked singularity at the endstate of gravitational collapse. Also we give conditions for the mass function when the singularity is gravitationally strong.

  7. The Detection of Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Blair, David G.

    2005-10-01

    Part I. An Introduction to Gravitational Waves and Methods for their Detection: 1. Gravitational waves in general relativity D. G. Blair; 2. Sources of gravitational waves D. G. Blair; 3. Gravitational wave detectors D. G. Blair; Part II. Gravitational Wave Detectors: 4. Resonant-bar detectors D. G. Blair; 5. Gravity wave dewars W. O. Hamilton; 6. Internal friction in high Q materials J. Ferreirinko; 7. Motion amplifiers and passive transducers J. P. Richard; 8. Parametric transducers P. J. Veitch; 9. Detection of continuous waves K. Tsubono; 10. Data analysis and algorithms for gravitational wave-antennas G. V. Paalottino; Part III. Laser Interferometer Antennas: 11. A Michelson interferometer using delay lines W. Winkler; 12. Fabry-Perot cavity gravity-wave detectors R. W. P. Drever; 13. The stabilisation of lasers for interferometric gravitational wave detectors J. Hough; 14. Vibration isolation for the test masses in interferometric gravitational wave detectors N. A. Robertson; 15. Advanced techniques A. Brillet; 16. Data processing, analysis and storage for interferometric antennas B. F. Schutz; 17. Gravitational wave detection at low and very low frequencies R. W. Hellings.

  8. Gravitational Physics Research

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    Gravitational physics research at ISPAE is connected with NASA's Relativity Mission (Gravity Probe B (GP-B)) which will perform a test of Einstein's General Relativity Theory. GP-B will measure the geodetic and motional effect predicted by General Relativity Theory with extremely stable and sensitive gyroscopes in an earth orbiting satellite. Both effects cause a very small precession of the gyroscope spin axis. The goal of the GP-B experiment is the measurement of the gyroscope precession with very high precision. GP-B is being developed by a team at Stanford University and is scheduled for launch in the year 2001. The related UAH research is a collaboration with Stanford University and MSFC. This research is focussed primarily on the error analysis and data reduction methods of the experiment but includes other topics concerned with experiment systems and their performance affecting the science measurements. The hydrogen maser is the most accurate and stable clock available. It will be used in future gravitational physics missions to measure relativistic effects such as the second order Doppler effect. The HMC experiment, currently under development at the Smithsonian Astrophysical Observatory (SAO), will test the performance and capability of the hydrogen maser clock for gravitational physics measurements. UAH in collaboration with the SAO science team will study methods to evaluate the behavior and performance of the HMC. The GP-B data analysis developed by the Stanford group involves complicated mathematical operations. This situation led to the idea to investigate alternate and possibly simpler mathematical procedures to extract the GP-B measurements form the data stream. Comparison of different methods would increase the confidence in the selected scheme.

  9. Gravitational violation of R parity and its cosmological signatures

    SciTech Connect

    Berezinsky, V. |; Joshipura, A.S.; Valle, J.W.

    1998-01-01

    Discrete R parity (R{sub P}) is usually imposed in the minimal supersymmetric standard model (MSSM) as an unbroken symmetry. In this paper we study very weak gravitationally induced R-parity breaking, described by nonrenormalizable terms inversely proportional to the Planck mass. The lightest supersymmetric particle, a neutralino, is unstable but its lifetime exceeds the age of the Universe and thus it can serve as a dark matter (DM) particle. The neutralino lifetime is severely constrained from below due to the production of positrons and antiprotons, diffuse gamma radiation, etc. The violation of R{sub P} generated gravitationally by dimension-five operators in the MSSM is shown to violate these constraints if they are suppressed only by the Planck scale. A general theoretical analysis of gravitationally induced R{sub P} violation is performed and two plausible and astrophysically consistent scenarios for achieving the required suppression are identified and discussed. {copyright} {ital 1997} {ital The American Physical Society}

  10. Does lunisolar gravitational tide affect the activity of animals?

    NASA Astrophysics Data System (ADS)

    Deshcherevskii, A. V.; Sidorin, A. Ya.

    2010-12-01

    Multiyear time series obtained by the continuous instrumental monitoring of the electrical activity (EA) of weakly electric fish Gnathonemus leopoldianus and the motor activity (MA) of the freshwater catfish Hoplosternum thoracatum and the cockroach Blaberus craniifer are compared to the parameters of the lunisolar gravitational tide. These curves are observed to be very similar for a large number of time intervals. However, a more detailed analysis shows this to be only a superficial resemblance caused by the closeness of the periods of diurnal and semidiurnal rhythms of bioindicator activity (the dominant rhythms in EA and MA patterns) and the periods of main gravitational tidal waves. It is concluded that the lunisolar gravitational tide has no significant effect on animal behavior in our experiment.

  11. Plasma Emission by Weak Turbulence Processes

    NASA Astrophysics Data System (ADS)

    Ziebell, L. F.; Yoon, P. H.; Gaelzer, R.; Pavan, J.

    2014-11-01

    The plasma emission is the radiation mechanism responsible for solar type II and type III radio bursts. The first theory of plasma emission was put forth in the 1950s, but the rigorous demonstration of the process based upon first principles had been lacking. The present Letter reports the first complete numerical solution of electromagnetic weak turbulence equations. It is shown that the fundamental emission is dominant and unless the beam speed is substantially higher than the electron thermal speed, the harmonic emission is not likely to be generated. The present findings may be useful for validating reduced models and for interpreting particle-in-cell simulations.

  12. The Properties of the Radio-Selected 1 Jy Sample of BL Lacertae Objects

    NASA Astrophysics Data System (ADS)

    Rector, Travis A.; Stocke, John T.

    2001-08-01

    We present new optical and near-IR spectroscopy, as well as new high dynamic range, arcsecond-resolution VLA radio maps, of BL Lacertae objects from the complete radio-selected ``1 jansky'' (1 Jy) sample (RBLs) for which such data were not previously available. Redshift information is now available for all but six of the 37 BL Lac objects in the 1 Jy sample. Of the 31 with redshift information, four redshifts are only minimum values based on absorption lines, and four other objects have uncertain redshifts based on the detection of only a single emission line. Unlike BL Lac objects from the complete X-ray-selected Einstein Medium Sensitivity Survey (EMSS) sample (XBLs), most RBLs possess weak but moderately luminous emission lines. The emission-line luminosities of RBLs are several orders of magnitude lower than flat-spectrum radio quasars (FSRQs); however, there is significant overlap in the luminosity distributions of the two classes. All but one object in the 1 Jy sample has now been observed with the VLA, and extended flux was detected for all but three of the observed objects. Whereas nearly all XBLs have extended power levels consistent with FR 1s, more than half of the RBLs have extended radio power levels too luminous to be beamed FR 1 radio galaxies. In fact, we find evidence for and examples of three distinct mechanisms for creating the BL Lac phenomenon in the 1 Jy sample: beamed FR 1s, beamed FR 2s, and possibly a few gravitationally lensed quasars. The value determined for the 1 Jy sample is 0.614+/-0.047, which is markedly different from the negative evolution seen in the EMSS and other XBL samples. A correlation between logarithmic X-ray-to-radio flux ratio and value is observed across the EMSS and 1 Jy samples from negative evolution in the more extreme XBLs to positive evolution in the more extreme RBLs. There is evidence that the selection criteria chosen by Stickel et al. eliminates some BL Lac objects from the 1 Jy sample

  13. Development of a direct experimental test for any violation of the equivalence principle by the weak interaction

    NASA Technical Reports Server (NTRS)

    Parker, P. D. M.

    1981-01-01

    Violation of the equivalence principle by the weak interaction is tested. Any variation of the weak interaction coupling constant with gravitational potential, i.e., a spatial variation of the fundamental constants is investigated. The level of sensitivity required for such a measurement is estimated on the basis of the size of a change in the gravitational potential which is accessible. The alpha particle spectrum is analyzed, and the counting rate was improved by a factor of approximately 100.

  14. Gravitinos from gravitational collapse

    SciTech Connect

    Grifols, J.A.; Masso, E.; Toldra, R.

    1998-01-01

    We reanalyze the limits on the gravitino mass m{sub 3/2} in superlight gravitino scenarios derived from arguments on energy loss during gravitational collapse. We conclude that the mass range 10{sup {minus}6} eV{le}m{sub 3/2}{le}2.3{times}10{sup {minus}5} eV is excluded by SN 1987A data. In terms of the scale of supersymmetry breaking {Lambda}, the range 70 GeV {le}{Lambda}{le}300 GeV is not allowed. {copyright} {ital 1997} {ital The American Physical Society}

  15. Regular gravitational lagrangians

    NASA Astrophysics Data System (ADS)

    Dragon, Norbert

    1992-02-01

    The Einstein action with vanishing cosmological constant is for appropriate field content the unique local action which is regular at the fixed point of affine coordinate transformations. Imposing this regularity requirement one excludes also Wess-Zumino counterterms which trade gravitational anomalies for Lorentz anomalies. One has to expect dilatational and SL (D) anomalies. If these anomalies are absent and if the regularity of the quantum vertex functional can be controlled then Einstein gravity is renormalizable. On leave of absence from Institut für Theoretische Physik, Universität Hannover, W-3000 Hannover 1, FRG.

  16. Weak bond screening system

    NASA Astrophysics Data System (ADS)

    Chuang, S. Y.; Chang, F. H.; Bell, J. R.

    Consideration is given to the development of a weak bond screening system which is based on the utilization of a high power ultrasonic (HPU) technique. The instrumentation of the prototype bond strength screening system is described, and the adhesively bonded specimens used in the system developmental effort are detailed. Test results obtained from these specimens are presented in terms of bond strength and level of high power ultrasound irradiation. The following observations were made: (1) for Al/Al specimens, 2.6 sec of HPU irradiation will screen weak bond conditions due to improper preparation of bonding surfaces; (2) for composite/composite specimens, 2.0 sec of HPU irradiation will disrupt weak bonds due to under-cured conditions; (3) for Al honeycomb core with composite skin structure, 3.5 sec of HPU irradiation will disrupt weak bonds due to bad adhesive or oils contamination of bonding surfaces; and (4) for Nomex honeycomb with Al skin structure, 1.3 sec of HPU irradiation will disrupt weak bonds due to bad adhesive.

  17. Gravitating lepton bag model

    NASA Astrophysics Data System (ADS)

    Burinskii, A.

    2015-08-01

    The Kerr-Newman (KN) black hole (BH) solution exhibits the external gravitational and electromagnetic field corresponding to that of the Dirac electron. For the large spin/mass ratio, a ≫ m, the BH loses horizons and acquires a naked singular ring creating two-sheeted topology. This space is regularized by the Higgs mechanism of symmetry breaking, leading to an extended particle that has a regular spinning core compatible with the external KN solution. We show that this core has much in common with the known MIT and SLAC bag models, but has the important advantage of being in accordance with the external gravitational and electromagnetic fields of the KN solution. A peculiar two-sheeted structure of Kerr's gravity provides a framework for the implementation of the Higgs mechanism of symmetry breaking in configuration space in accordance with the concept of the electroweak sector of the Standard Model. Similar to other bag models, the KN bag is flexible and pliant to deformations. For parameters of a spinning electron, the bag takes the shape of a thin rotating disk of the Compton radius, with a ring-string structure and a quark-like singular pole formed at the sharp edge of this disk, indicating that the considered lepton bag forms a single bag-string-quark system.

  18. General Relativity and Gravitation

    NASA Astrophysics Data System (ADS)

    Ashtekar, Abhay; Berger, Beverly; Isenberg, James; MacCallum, Malcolm

    2015-07-01

    Part I. Einstein's Triumph: 1. 100 years of general relativity George F. R. Ellis; 2. Was Einstein right? Clifford M. Will; 3. Cosmology David Wands, Misao Sasaki, Eiichiro Komatsu, Roy Maartens and Malcolm A. H. MacCallum; 4. Relativistic astrophysics Peter Schneider, Ramesh Narayan, Jeffrey E. McClintock, Peter Mészáros and Martin J. Rees; Part II. New Window on the Universe: 5. Receiving gravitational waves Beverly K. Berger, Karsten Danzmann, Gabriela Gonzalez, Andrea Lommen, Guido Mueller, Albrecht Rüdiger and William Joseph Weber; 6. Sources of gravitational waves. Theory and observations Alessandra Buonanno and B. S. Sathyaprakash; Part III. Gravity is Geometry, After All: 7. Probing strong field gravity through numerical simulations Frans Pretorius, Matthew W. Choptuik and Luis Lehner; 8. The initial value problem of general relativity and its implications Gregory J. Galloway, Pengzi Miao and Richard Schoen; 9. Global behavior of solutions to Einstein's equations Stefanos Aretakis, James Isenberg, Vincent Moncrief and Igor Rodnianski; Part IV. Beyond Einstein: 10. Quantum fields in curved space-times Stefan Hollands and Robert M. Wald; 11. From general relativity to quantum gravity Abhay Ashtekar, Martin Reuter and Carlo Rovelli; 12. Quantum gravity via unification Henriette Elvang and Gary T. Horowitz.

  19. Gravitational Neurobiology of Fish

    NASA Astrophysics Data System (ADS)

    Rahmann, H.; Anken, R. H.

    In vertebrates (including man), altered gravitational environments such as weightlessness can induce malfunctions of the inner ears, based on irregular movements of the semicircular cristae or on dislocations of the inner ear otoliths from the corresponding sensory epithelia. This will lead to illusionary tilts, since the vestibular inputs are not confirmed by the other sensory organs, which results in an intersensory conflict. Vertebrates in orbit therefore face severe orientation problems. In humans, the intersensory conflict may additionally lead to a malaise, commonly referred to as space motion sickness (SMS), a kinetosis. During the first days at weightlessness, the orientation problems (and SMS) disappear, since the brain develops a new compensatory interpretation of the available sensory data. The present review reports on the neurobiological responses - particularly of fish - observed at altered gravitational states, concerning behaviour and neuroplastic reactivities. Recent investigations employing microgravity (spaceflight, parabolic aircraft flights, clinostat) and hyper-gravity (laboratory centrifuges as ground based research tools) yielded clues and insights into the understanding of the respective basic phenomena

  20. Gravitating lepton bag model

    SciTech Connect

    Burinskii, A.

    2015-08-15

    The Kerr–Newman (KN) black hole (BH) solution exhibits the external gravitational and electromagnetic field corresponding to that of the Dirac electron. For the large spin/mass ratio, a ≫ m, the BH loses horizons and acquires a naked singular ring creating two-sheeted topology. This space is regularized by the Higgs mechanism of symmetry breaking, leading to an extended particle that has a regular spinning core compatible with the external KN solution. We show that this core has much in common with the known MIT and SLAC bag models, but has the important advantage of being in accordance with the external gravitational and electromagnetic fields of the KN solution. A peculiar two-sheeted structure of Kerr’s gravity provides a framework for the implementation of the Higgs mechanism of symmetry breaking in configuration space in accordance with the concept of the electroweak sector of the Standard Model. Similar to other bag models, the KN bag is flexible and pliant to deformations. For parameters of a spinning electron, the bag takes the shape of a thin rotating disk of the Compton radius, with a ring–string structure and a quark-like singular pole formed at the sharp edge of this disk, indicating that the considered lepton bag forms a single bag–string–quark system.

  1. Monitoring Radio Frequency Interference in Southwest Virginia

    NASA Astrophysics Data System (ADS)

    Rapp, Steve

    2010-01-01

    The radio signals received from astronomical objects are extremely weak. Because of this, radio sources are easily shrouded by interference from devices such as satellites and cell phone towers. Radio astronomy is very susceptible to this radio frequency interference (RFI). Possibly even worse than complete veiling, weaker interfering signals can contaminate the data collected by radio telescopes, possibly leading astronomers to mistaken interpretations. To help promote student awareness of the connection between radio astronomy and RFI, an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project_the result of a collaboration between the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the National Radio Astronomy Observatory (NRAO)_encourages students to collect and analyze RFI data and develop conclusions as a team. Because the project focuses on electromagnetic radiation, it is appropriate for physics, physical science, chemistry, or general science classes. My class-about 50 students from 15 southwest Virginia high schools-participated in the Quiet Skies Project and were pioneers in the use of the beta version of the Quiet Skies Detector (QSD), which is used to detect RFI. Students have been involved with the project since 2005 and have collected and shared data with NRAO. In analyzing the data they have noted some trends in RFI in Southwest Virginia.

  2. Pixelation Effects in Weak Lensing

    NASA Astrophysics Data System (ADS)

    High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

    2007-11-01

    Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, & Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09" for a 0.14" FWHM point-spread function (PSF). The pixel scale could be increased to ~0.16" if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape

  3. Gravitational radiation from neutron stars deformed by crustal Hall drift

    NASA Astrophysics Data System (ADS)

    Suvorov, A. G.; Mastrano, A.; Geppert, U.

    2016-07-01

    A precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. Their creation can proceed via crustal Hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined completely to the crust and another which penetrates the whole star. The aim of this study is to explore whether these magnetic structures in the crust can deform the star sufficiently to make it an observable source of gravitational waves. We model the evolution of these field configurations, which can develop, within ˜104-105 yr, magnetic spots with local surface field strengths ˜1014 G maintained over ≳106 yr. Deformations caused by the magnetic forces are calculated. We show that, under favourable initial conditions, a star undergoing crustal Hall drift can have ellipticity ɛ ˜ 10-6, even with sub-magnetar polar field strengths, after ˜105 yr. A pulsar rotating at ˜102 Hz with such ɛ is a promising gravitational wave source candidate. Since such large deformations can be caused only by a particular magnetic field configuration that penetrates the whole star and whose maximum magnetic energy is concentrated in the outer core region, gravitational wave emission observed from radio pulsars can thus inform us about the internal field structures of young neutron stars.

  4. Gravitational Microlensing Events as a Target for the SETI project

    NASA Astrophysics Data System (ADS)

    Rahvar, Sohrab

    2016-09-01

    The detection of signals from a possible extrasolar technological civilization is one of the most challenging efforts of science. In this work, we propose using natural telescopes made of single or binary gravitational lensing systems to magnify leakage of electromagnetic signals from a remote planet that harbors Extraterrestrial Intelligent (ETI) technology. Currently, gravitational microlensing surveys are monitoring a large area of the Galactic bulge to search for microlensing events, finding more than 2000 events per year. These lenses are capable of playing the role of natural telescopes, and, in some instances, they can magnify radio band signals from planets orbiting around the source stars in gravitational microlensing systems. Assuming that the frequency of electromagnetic waves used for telecommunication in ETIs is similar to ours, we propose follow-up observation of microlensing events with radio telescopes such as the Square Kilometre Array (SKA), the Low Frequency Demonstrators, and the Mileura Wide-Field Array. Amplifying signals from the leakage of broadcasting by an Earth-like civilization will allow us to detect them as far as the center of the Milky Way galaxy. Our analysis shows that in binary microlensing systems, the probability of amplification of signals from ETIs is more than that in single microlensing events. Finally, we propose the use of the target of opportunity mode for follow-up observations of binary microlensing events with SKA as a new observational program for searching ETIs. Using optimistic values for the factors of the Drake equation provides detection of about one event per year.

  5. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    NASA Astrophysics Data System (ADS)

    Mingarelli, Chiara; Levin, Janna; Lazio, Joseph

    2016-03-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs), NS-BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak. The main burst is from the peak luminosity before merger, while the post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS-BH pairs are desirable for ground-based gravitational wave (GW) observatories since the pair might not be detected any other way, with EM counterparts augmenting the scientific leverage beyond the GW signal. Valuably, EM signal can break degeneracies in the parameters encoded in the GW as well as probe the NS magnetic field strength, yielding insights into open problems in NS magnetic field decay.

  6. String pair production in a time-dependent gravitational field

    SciTech Connect

    Tolley, Andrew J.; Wesley, Daniel H.

    2005-12-15

    We study the pair creation of point particles and strings in a time-dependent, weak gravitational field. We find that, for massive string states, there are surprising and significant differences between the string and point-particle results. Central to our approach is the fact that a weakly curved spacetime can be represented by a coherent state of gravitons, and therefore we employ standard techniques in string perturbation theory. String and point-particle pairs are created through tree-level interactions between the background gravitons. In particular, we focus on the production of excited string states and perform explicit calculations of the production of a set of string states of arbitrary excitation level. The differences between the string and point-particle results may contain important lessons for the pair production of strings in the strong gravitational fields of interest in cosmology and black hole physics.

  7. Gravitational waves from binary supermassive black holes missing in pulsar observations.

    PubMed

    Shannon, R M; Ravi, V; Lentati, L T; Lasky, P D; Hobbs, G; Kerr, M; Manchester, R N; Coles, W A; Levin, Y; Bailes, M; Bhat, N D R; Burke-Spolaor, S; Dai, S; Keith, M J; Osłowski, S; Reardon, D J; van Straten, W; Toomey, L; Wang, J-B; Wen, L; Wyithe, J S B; Zhu, X-J

    2015-09-25

    Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems would modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrained the characteristic amplitude of this background, A(c,yr), to be <1.0 × 10(-15) with 95% confidence. This limit excludes predicted ranges for A(c,yr) from current models with 91 to 99.7% probability. We conclude that binary evolution is either stalled or dramatically accelerated by galactic-center environments and that higher-cadence and shorter-wavelength observations would be more sensitive to gravitational waves.

  8. Gravitational waves from binary supermassive black holes missing in pulsar observations.

    PubMed

    Shannon, R M; Ravi, V; Lentati, L T; Lasky, P D; Hobbs, G; Kerr, M; Manchester, R N; Coles, W A; Levin, Y; Bailes, M; Bhat, N D R; Burke-Spolaor, S; Dai, S; Keith, M J; Osłowski, S; Reardon, D J; van Straten, W; Toomey, L; Wang, J-B; Wen, L; Wyithe, J S B; Zhu, X-J

    2015-09-25

    Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems would modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrained the characteristic amplitude of this background, A(c,yr), to be <1.0 × 10(-15) with 95% confidence. This limit excludes predicted ranges for A(c,yr) from current models with 91 to 99.7% probability. We conclude that binary evolution is either stalled or dramatically accelerated by galactic-center environments and that higher-cadence and shorter-wavelength observations would be more sensitive to gravitational waves. PMID:26404832

  9. Weak shock reflection

    NASA Astrophysics Data System (ADS)

    Hunter, John K.; Brio, Moysey

    2000-05-01

    We present numerical solutions of a two-dimensional inviscid Burgers equation which provides an asymptotic description of the Mach reflection of weak shocks. In our numerical solutions, the incident, reflected, and Mach shocks meet at a triple point, and there is a supersonic patch behind the triple point, as proposed by Guderley for steady weak-shock reflection. A theoretical analysis indicates that there is an expansion fan at the triple point, in addition to the three shocks. The supersonic patch is extremely small, and this work is the first time it has been resolved.

  10. Constraints on gravitational properties of antimatter from cyclotron-frequency measurements

    NASA Astrophysics Data System (ADS)

    Holzscheiter, Michael H.

    2014-05-01

    A fundamental question in physics that has yet to be addressed experimentally is whether particles of antimatter, such as the antiproton or positron, obey the weak equivalence principle (WEP). Several theoretical arguments have been put forward arguing limits for possible violations of WEP. No direct `classical' gravitational experiment, the measurement of the free fall of an antiparticle, has been performed to date to determine if a particle of antimatter would experience a force in the gravitational potential of a normal matter body that is different from normal gravity. 30 years ago we proposed a free fall experiment using protons and antiprotons, modeled after the experiment to measure the gravitational acceleration of a free electron. At that time we gave consideration to yet another possible observation of gravitational differences between matter and antimatter based on the gravitational red shift of clocks. I will recall the original arguments and make a number of comments pertaining to the technical problems and other issues that prevented the execution of the antiproton free fall measurement. Note that a different gravitational force on antimatter in the gravitational field of matter would not constitute a violation of CPT, as this is only concerned with the gravitational acceleration of antimatter in the gravitational field of an antimatter body.

  11. Radio frequency detection assembly and method for detecting radio frequencies

    DOEpatents

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  12. Gravitational Instability of Cylindrical Viscoelastic Medium Permeated with Non Uniform Magnetic Field and Rotation

    NASA Astrophysics Data System (ADS)

    Dhiman, Joginder Singh; Sharma, Rajni

    2016-03-01

    The self-gravitating instability of an infinitely extending axisymmetric cylinder of viscoelastic medium permeated with non uniform magnetic field and rotation is studied for both the strongly coupled plasma (SCP) and weakly coupled plasma (WCP). The non uniform magnetic field and rotation are considered to act along the axial direction of the cylinder. The normal mode method of perturbations is applied to obtain the dispersion relation. The condition for the onset of gravitational instability has been derived from the dispersion relation under both strongly and weakly coupling limits. It is found that the Jeans criterion for gravitational collapse gets modified due to the presence of shear and bulk viscosities for the SCP, however, the magnetic field and rotation whether uniform or non uniform has no effect on the Jeans criterion of an infinitely extending axisymmetric cylinder of a self-gravitating viscoelastic medium.

  13. Numerical simulations of self-gravitating magnetized disks

    NASA Astrophysics Data System (ADS)

    Fromang, S.; de Villiers, J.-P.; Balbus, S.

    In the early phases of their evolution, protoplanetary disks are massive enough for self-gravitating effects to be important. This is for example the case of disks around Class 0 and some Class I protostars, but other peculiar and more evolved cases may exist, like the circumbinary disk of GG Tau. On larger scales, the central parts of our galaxy show an m=1 density wave, and the disks feeding supermassive black holes in the heart of AGNs are certainly self-gravitating. At the same time, these objects are prone to the development of the magnetorotational instability (MRI) if a weak magnetic field is present. It is therefore relevant to address the question of the evolution of a system under the simultaneous effects of the MRI and gravitational instabilities. These instabilities may dramatically influence the early evolution of protoplanetary disks, and, as a result, planet formation itself. In this talk, I will present a first view on these issues, by means of 2D and 3D MHD numerical simulations of self-gravitating magnetized torii. To date, these simulations are the first examples of the behaviour of the MRI in a self-gravitating environment.

  14. Quantum states of neutrons in the Earth's gravitational field.

    PubMed

    Nesvizhevsky, Valery V; Börner, Hans G; Petukhov, Alexander K; Abele, Hartmut; Baessler, Stefan; Ruess, Frank J; Stöferle, Thilo; Westphal, Alexander; Gagarski, Alexei M; Petrov, Guennady A; Strelkov, Alexander V

    2002-01-17

    The discrete quantum properties of matter are manifest in a variety of phenomena. Any particle that is trapped in a sufficiently deep and wide potential well is settled in quantum bound states. For example, the existence of quantum states of electrons in an electromagnetic field is responsible for the structure of atoms, and quantum states of nucleons in a strong nuclear field give rise to the structure of atomic nuclei. In an analogous way, the gravitational field should lead to the formation of quantum states. But the gravitational force is extremely weak compared to the electromagnetic and nuclear force, so the observation of quantum states of matter in a gravitational field is extremely challenging. Because of their charge neutrality and long lifetime, neutrons are promising candidates with which to observe such an effect. Here we report experimental evidence for gravitational quantum bound states of neutrons. The particles are allowed to fall towards a horizontal mirror which, together with the Earth's gravitational field, provides the necessary confining potential well. Under such conditions, the falling neutrons do not move continuously along the vertical direction, but rather jump from one height to another, as predicted by quantum theory.

  15. Self-gravitating disc candidates around massive young stars

    NASA Astrophysics Data System (ADS)

    Forgan, D. H.; Ilee, J. D.; Cyganowski, C. J.; Brogan, C. L.; Hunter, T. R.

    2016-11-01

    There have been several recent detections of candidate Keplerian discs around massive young protostars. Given the relatively large disc-to-star mass ratios in these systems, and their young ages, it is worth investigating their propensity to becoming self-gravitating. To this end, we compute self-consistent, semi-analytic models of putative self-gravitating discs for five candidate disc systems. Our aim is not to fit exactly the observations, but to demonstrate that the expected dust continuum emission from marginally unstable self-gravitating discs can be quite weak, due to high optical depth at the mid-plane even at millimetre wavelengths. In the best cases, the models produce `observable' disc masses within a factor of <1.5 of those observed, with mid-plane dust temperatures comparable to measured temperatures from molecular line emission. We find in two cases that a self-gravitating disc model compares well with observations. If these discs are self-gravitating, they satisfy the conditions for disc fragmentation in their outer regions. These systems may hence have as-yet-unresolved low-mass stellar companions, and are thus promising targets for future high angular resolution observations.

  16. Constraints on primordial density perturbations from induced gravitational waves

    SciTech Connect

    Assadullahi, Hooshyar; Wands, David

    2010-01-15

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

  17. Gravitational Repulsion and Dirac Antimatter

    NASA Astrophysics Data System (ADS)

    Kowitt, Mark E.

    1996-03-01

    Based on an analogy with electron and hole dynamics in semiconductors, Dirac's relativistic electron equation is generalized to include a gravitational interaction using an electromagnetic-type approximation of the gravitational potential. With gravitational and inertial masses decoupled, the equation serves to extend Dirac's deduction of antimatter parameters to include the possibility of gravitational repulsion between matter and antimatter. Consequences for general relativity and related “antigravity” issues are considered, including the nature and gravitational behavior of virtual photons, virtual pairs, and negative-energy particles. Basic cosmological implications of antigravity are explored—in particular, potential contributions to inflation, expansion, and the general absence of detectable antimatter. Experimental and observational tests are noted, and new ones suggested.

  18. FAST RADIO BURSTS AND RADIO TRANSIENTS FROM BLACK HOLE BATTERIES

    SciTech Connect

    Mingarelli, Chiara M. F.; Levin, Janna; Lazio, T. Joseph W.

    2015-12-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally, the luminosity was expected to be in high-energy X-rays or gamma-rays, however, we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs; millisecond-scale radio transients) NS–BH coalescence rates are too low to make these a primary FRB source. Instead, we propose that the transients form a FRB sub-population, distinguishable by a double peak with a precursor. The rapid ramp-up in luminosity manifests as a precursor to the burst which is 20%–80% as luminous given 0.5 ms timing resolution. The main burst arises from the peak luminosity before the merger. The post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS–BH pairs are especially desirable for ground-based gravitational wave (GW) observatories since the pair might not otherwise be detected, with EM counterparts greatly augmenting the scientific leverage beyond the GW signal. The EM signal’s ability to break degeneracies in the parameters encoded in the GW and probe the NS magnetic field strength is quite valuable, yielding insights into open problems in NS magnetic field decay.

  19. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    NASA Astrophysics Data System (ADS)

    Mingarelli, Chiara M. F.; Levin, Janna; Lazio, T. Joseph W.

    2015-12-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally, the luminosity was expected to be in high-energy X-rays or gamma-rays, however, we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs; millisecond-scale radio transients) NS–BH coalescence rates are too low to make these a primary FRB source. Instead, we propose that the transients form a FRB sub-population, distinguishable by a double peak with a precursor. The rapid ramp-up in luminosity manifests as a precursor to the burst which is 20%–80% as luminous given 0.5 ms timing resolution. The main burst arises from the peak luminosity before the merger. The post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS–BH pairs are especially desirable for ground-based gravitational wave (GW) observatories since the pair might not otherwise be detected, with EM counterparts greatly augmenting the scientific leverage beyond the GW signal. The EM signal’s ability to break degeneracies in the parameters encoded in the GW and probe the NS magnetic field strength is quite valuable, yielding insights into open problems in NS magnetic field decay.

  20. In praise of weakness

    NASA Astrophysics Data System (ADS)

    Steinberg, Aephraim; Feizpour, Amir; Rozema; Mahler; Hayat

    2013-03-01

    Quantum physics is being transformed by a radical new conceptual and experimental approach known as weak measurement that can do everything from tackling basic quantum mysteries to mapping the trajectories of photons in a Young's double-slit experiment. Aephraim Steinberg, Amir Feizpour, Lee Rozema, Dylan Mahler and Alex Hayat unveil the power of this new technique.

  1. The radio sources CTA 21 and OF+247: The hot spots of radio galaxies

    NASA Astrophysics Data System (ADS)

    Artyukh, V. S.; Tyul'bashev, S. A.; Chernikov, P. A.

    2013-06-01

    The physical conditions in the radio sources CTA 21 and OF+247 are studied assuming that the low-frequency spectral turnovers are due to synchrotron self-absorption. The physical parameters of the radio sources are estimated using a technique based on a nonuniform synchrotron source model. It is shown that the magnetic-field distributions in the dominant compact components of these radio sources are strongly inhomogeneous. The magnetic fields at the center of the sources are B ˜ 10-1 G, and the fields are two to three orders of magnitude weaker at the periphery. The magnetic field averaged over the compact component is B ˜ 10-3 G, and the density of relativistic electrons is n e ˜ 10-3 cm-3. Assuming that there is equipartition of the energies of the magnetic field and relativistic particles, averaged over the source, < E H > = < E e > ˜ 10-7-10-6 erg cm-3. The energy density of the magnetic field exceeds that of the relativistic electrons at the centers of the radio sources. The derived parameters of CTA 21 and OF+247 are close to those of the hot spots in the radio galaxy Cygnus A. On this basis, it is suggested that CTA 21 and OF+247 are radio galaxies at an early stage of their evolution, when the hot spots (dominant compact radio components) have appeared, and the radio lobes (weak extended components) are still being formed.

  2. Hypernuclear Weak Decays

    NASA Astrophysics Data System (ADS)

    Itonaga, K.; Motoba, T.

    The recent theoretical studies of Lambda-hypernuclear weak decaysof the nonmesonic and pi-mesonic ones are developed with the aim to disclose the link between the experimental decay observables and the underlying basic weak decay interactions and the weak decay mechanisms. The expressions of the nonmesonic decay rates Gamma_{nm} and the decay asymmetry parameter alpha_1 of protons from the polarized hypernuclei are presented in the shell model framework. We then introduce the meson theoretical Lambda N -> NN interactions which include the one-meson exchanges, the correlated-2pi exchanges, and the chiral-pair-meson exchanges. The features of meson exchange potentials and their roles on the nonmesonic decays are discussed. With the adoption of the pi + 2pi/rho + 2pi/sigma + omega + K + rhopi/a_1 + sigmapi/a_1 exchange potentials, we have carried out the systematic calculations of the nonmesonic decay observables for light-to-heavy hypernuclei. The present model can account for the available experimental data of the decay rates, Gamma_n/Gamma_p ratios, and the intrinsic asymmetry parameters alpha_Lambda (alpha_Lambda is related to alpha_1) of emitted protons well and consistently within the error bars. The hypernuclear lifetimes are evaluated by converting the total weak decay rates Gamma_{tot} = Gamma_pi + Gamma_{nm} to tau, which exhibit saturation property for the hypernuclear mass A ≥ 30 and agree grossly well with experimental data for the mass range from light to heavy hypernuclei except for the very light ones. Future extensions of the model and the remaining problems are also mentioned. The pi-mesonic weak processes are briefly surveyed, and the calculations and predictions are compared and confirmed by the recent high precision FINUDA pi-mesonic decay data. This shows that the theoretical basis seems to be firmly grounded.

  3. Tests of the weak equivalence principle

    NASA Astrophysics Data System (ADS)

    Speake, C. C.; Will, C. M.

    2012-09-01

    The Einstein equivalence principle is the foundation for general relativity and all metric theories of gravity. Of its three tenets—the equality of acceleration of test bodies, or weak equivalence principle; the validity of Lorentz invariance in local freely falling frames; and the position invariance of local physical laws—the weak equivalence principle has played the most important role historically, and continues to be a focus of intense theoretical and experimental investigation. From the probably apocryphal 16th century demonstrations by Galileo at Pisa's leaning tower to the sensitive torsion-balance measurements of today (both pictured on the cover of this issue), this principle, dubbed WEP, has been crucial to the development of gravitation theory. The universality of the rate of acceleration of all types of matter in a gravitational field can be taken as evidence that gravitation is fundamentally determined by the geometry, or metric, of spacetime. Newton began his magnum opus 'The Principia' with a discussion of WEP and his experiments to verify it, while Einstein took WEP for granted in his construction of general relativity, never once referring to the epochal experiments by Baron Eötvös. The classic 1964 experiment of Roll, Krotkov and Dicke ushered in the modern era of high-precision tests, and the search for a 'fifth force' during the late 1980s (instigated, ironically, by purported anomalies in Eötvös's old data) caused the enterprise to pivot from pure tests of the foundation of GR to searches for new physics beyond the standard model of the non-gravitational interactions. Today, the next generation of experimental tests of WEP are being prepared for launch or are being developed, with the goal of reaching unprecedented levels of sensitivity, in search of signatures of interactions inspired by string theory, extra dimensions and other concepts from the world of high-energy physics. At the same time observations continue using lunar laser

  4. Limits on gravitational-wave emission from selected pulsars using LIGO data.

    PubMed

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

    2005-05-13

    We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars. PMID:15904354

  5. The deflection of light induced by the Sun's gravitational field and measured with geodetic VLBI

    NASA Astrophysics Data System (ADS)

    Titov, O.; Girdiuk, A.

    2015-08-01

    The Sun's gravitational field deflects the apparent positions of close objects in accordance with the formulae of general relativity. Optical astrometry is used to test the prediction, but only with the stars close to the Sun and only during total Solar eclipses. Geodetic Very Long Baseline Interferometry (VLBI) is capable of measuring the deflection of the light from distant radio sources anytime and across the whole sky. We show that the effect of light deflection is equivalent to the gravitational delay calculated during the reduction of VLBI data. All reference radio sources display an annual circular motion with the magnitude proportional to their ecliptic latitude. In particular, radio sources near the ecliptic pole draw an annual circle with magnitude of 4~mas. This effect could be easily measured with the current precision of the geodetic VLBI data.

  6. Galaxies as gravitational lenses.

    PubMed

    Sadeh, D

    1967-12-01

    The probability that a galaxy gathers light from another remote galaxy, and deflects and focuses it toward an observer on Earth, is calculated according to various cosmologic models. I pose the question of whether an object called a quasar is a single, intrinsically luminous entity or the result of accidental alignment, along the line of sight, of two normal galaxies, the more distant of which has its light amplified by the gravitational-lens effect of the nearer galaxy. If galaxies are distributed at random in the universe, the former alternative is true. But, if we assume that most galaxies exist in pairs, we can find about 30 galaxies occurring exactly one behind the other in such a way as to enable amplification of the order of 50. This model explains also the variations in intensity in quasars, but fails to explain others of their observed properties. PMID:17734305

  7. Bubble collision with gravitation

    SciTech Connect

    Hwang, Dong-il; Lee, Bum-Hoon; Lee, Wonwoo; Yeom, Dong-han E-mail: bhl@sogang.ac.kr E-mail: innocent.yeom@gmail.com

    2012-07-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  8. Frontiers in gravitational physics

    NASA Astrophysics Data System (ADS)

    Dutta, Koushik

    In this thesis we present three research projects in classical General Relativity and Cosmology. In the first part of the thesis we investigate the definition of gravitational charge corresponding to the asymptotic boost symmetry of a spacetime and derive its role in the first law of black hole thermodynamics. In the cosmology part, we investigate the role of a scalar field in the early and late time evolution of the Universe. We find out observational constraints on the pseudo Nambu Goldstone Boson quintessence model using the latest supernova and Cosmic Microwave Background (CMB) data. In an attempt to explain a particular anomaly in the latest CMB data, we propose a modification to the standard single field inflation based on the initial kinetic energy domination with anisotropic initial conditions. Predictions of this mechanism can be tested in future data analysis.

  9. Atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Goldman, I.

    1982-01-01

    Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity, respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous - whose rates are related by a non-constant function beta sub a - is demonstrated. The cosmological character of beta sub a is also discussed.

  10. Gravitational adaptation of animals

    NASA Technical Reports Server (NTRS)

    Smith, A. H.; Burton, R. R.

    1982-01-01

    The effect of gravitational adaptation is studied in a group of five Leghorn cocks which had become physiologically adapted to 2 G after 162 days of centrifugation. After this period of adaptation, they are periodically exposed to a 2 G field, accompanied by five previously unexposed hatch-mates, and the degree of retained acceleration adaptation is estimated from the decrease in lymphocyte frequency after 24 hr at 2 G. Results show that the previously adapted birds exhibit an 84% greater lymphopenia than the unexposed birds, and that the lymphocyte frequency does not decrease to a level below that found at the end of 162 days at 2 G. In addition, the capacity for adaptation to chronic acceleration is found to be highly heritable. An acceleration tolerant strain of birds shows lesser mortality during chronic acceleration, particularly in intermediate fields, although the result of acceleration selection is largely quantitative (a greater number of survivors) rather than qualitative (behavioral or physiological changes).

  11. Earth Gravitational Model 2020

    NASA Astrophysics Data System (ADS)

    Barnes, D.; Factor, J. K.; Holmes, S. A.; Ingalls, S.; Presicci, M. R.; Beale, J.; Fecher, T.

    2015-12-01

    The National Geospatial-Intelligence Agency [NGA], in conjunction with its U.S. and international partners, has begun preliminary work on its next Earth Gravitational Model, to replace EGM2008. The new 'Earth Gravitational Model 2020' [EGM2020] has an expected public release date of 2020, and will likely retain the same harmonic basis and resolution as EGM2008. As such, EGM2020 will be essentially an ellipsoidal harmonic model up to degree (n) and order (m) 2159, but will be released as a spherical harmonic model to degree 2190 and order 2159. EGM2020 will benefit from new data sources and procedures. Updated satellite gravity information from the GOCE and GRACE mission, will better support the lower harmonics, globally. Multiple new acquisitions (terrestrial, airborne and shipborne) of gravimetric data over specific geographical areas, will provide improved global coverage and resolution over the land, as well as for coastal and some ocean areas. Ongoing accumulation of satellite altimetry data as well as improvements in the treatment of this data, will better define the marine gravity field, most notably in polar and near-coastal regions. NGA and partners are evaluating different approaches for optimally combining the new GOCE/GRACE satellite gravity models with the terrestrial data. These include the latest methods employing a full covariance adjustment. NGA is also working to assess systematically the quality of its entire gravimetry database, towards correcting biases and other egregious errors where possible, and generating improved error models that will inform the final combination with the latest satellite gravity models. Outdated data gridding procedures have been replaced with improved approaches. For EGM2020, NGA intends to extract maximum value from the proprietary data that overlaps geographically with unrestricted data, whilst also making sure to respect and honor its proprietary agreements with its data-sharing partners.

  12. Gravitational waves from rotating and precessing rigid bodies. 2: General solutions and computationally useful formulae

    NASA Technical Reports Server (NTRS)

    Zimmerman, M.

    1979-01-01

    The classical mechanics results for free precession which are needed in order to calculate the weak field, slow-motion, quadrupole-moment gravitational waves are reviewed. Within that formalism, algorithms are given for computing the exact gravitational power radiated and waveforms produced by arbitrary rigid-body freely-precessing sources. The dominant terms are presented in series expansions of the waveforms for the case of an almost spherical object precessing with a small wobble angle. These series expansions, which retain the precise frequency dependence of the waves, may be useful for gravitational astronomers when freely-precessing sources begin to be observed.

  13. Beyond concordance cosmology with magnification of gravitational-wave standard sirens.

    PubMed

    Camera, Stefano; Nishizawa, Atsushi

    2013-04-12

    We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe's large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer. PMID:25167243

  14. The perturbation of gravitational waves in plasma in the FRW space-time

    NASA Astrophysics Data System (ADS)

    Youssef, Manal H.

    2016-01-01

    In this paper we study the perturbation of gravitational waves in plasma,using the relativistic hydro-magnetic equation in the so-called Cowling approximation considering a Friedman-Robertson-Walker (FRW) cosmological model. It has been assumed the gravitational field and the weak magnetic field do not break the homogeneity and isotropy of the considered FRW space time. Applying the formalism proposed for Zel'dovich and Novikov (The structure and evolution of the universe, Volume II, 1983), Brandenburg et al. (Phys. Rev. D 54:1291, 1996) and Weinberg (Gravitation and Cosmology, 1972). We verify that density fluctuation may be obtained.

  15. On the unreasonable effectiveness of the post-Newtonian approximation in gravitational physics.

    PubMed

    Will, Clifford M

    2011-04-12

    The post-Newtonian approximation is a method for solving Einstein's field equations for physical systems in which motions are slow compared to the speed of light and where gravitational fields are weak. Yet it has proven to be remarkably effective in describing certain strong-field, fast-motion systems, including binary pulsars containing dense neutron stars and binary black hole systems inspiraling toward a final merger. The reasons for this effectiveness are largely unknown. When carried to high orders in the post-Newtonian sequence, predictions for the gravitational-wave signal from inspiraling compact binaries will play a key role in gravitational-wave detection by laser-interferometric observatories.

  16. Beyond concordance cosmology with magnification of gravitational-wave standard sirens.

    PubMed

    Camera, Stefano; Nishizawa, Atsushi

    2013-04-12

    We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe's large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer.

  17. Beyond Concordance Cosmology with Magnification of Gravitational-Wave Standard Sirens

    NASA Astrophysics Data System (ADS)

    Camera, Stefano; Nishizawa, Atsushi

    2013-04-01

    We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe’s large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer.

  18. DETECTION, LOCALIZATION, AND CHARACTERIZATION OF GRAVITATIONAL WAVE BURSTS IN A PULSAR TIMING ARRAY

    SciTech Connect

    Finn, Lee Samuel; Lommen, Andrea N.

    2010-08-01

    Efforts to detect gravitational waves by timing an array of pulsars have traditionally focused on stationary gravitational waves, e.g., stochastic or periodic signals. Gravitational wave bursts-signals whose duration is much shorter than the observation period-will also arise in the pulsar timing array waveband. Sources that give rise to detectable bursts include the formation or coalescence of supermassive black holes (SMBHs), the periapsis passage of compact objects in highly elliptic or unbound orbits about an SMBH, or cusps on cosmic strings. Here, we describe how pulsar timing array data may be analyzed to detect and characterize these bursts. Our analysis addresses, in a mutually consistent manner, a hierarchy of three questions. (1) What are the odds that a data set includes the signal from a gravitational wave burst? (2) Assuming the presence of a burst, what is the direction to its source? (3) Assuming the burst propagation direction, what is the burst waveform's time dependence in each of its polarization states? Applying our analysis to synthetic data sets, we find that we can detect gravitational waves even when the radiation is too weak to either localize the source or infer the waveform, and detect and localize sources even when the radiation amplitude is too weak to permit the waveform to be determined. While the context of our discussion is gravitational wave detection via pulsar timing arrays, the analysis itself is directly applicable to gravitational wave detection using either ground- or space-based detector data.

  19. Spherical gravitational collapse in N dimensions

    SciTech Connect

    Goswami, Rituparno; Joshi, Pankaj S.

    2007-10-15

    We investigate here spherically symmetric gravitational collapse in a space-time with an arbitrary number of dimensions and with a general type I matter field, which is a broad class that includes most of the physically reasonable matter forms. We show that given the initial data for matter in terms of the initial density and pressure profiles at an initial surface t=t{sub i} from which the collapse evolves, there exist the rest of the initial data functions and classes of solutions of Einstein equations which we construct here, such that the space-time evolution goes to a final state which is either a black hole or a naked singularity, depending on the nature of initial data and evolutions chosen, and subject to validity of the weak energy condition. The results are discussed and analyzed in the light of the cosmic censorship hypothesis in black hole physics. The formalism here combines the earlier results on gravitational collapse in four dimensions in a unified treatment. Also the earlier work is generalized to higher-dimensional space-times to allow a study of the effect of the number of dimensions on the possible final outcome of the collapse in terms of either a black hole or naked singularity. No restriction is adopted on the number of dimensions, and other limiting assumptions such as self-similarity of space-time are avoided, in order to keep the treatment general. Our methodology allows us to consider to an extent the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse.

  20. Spherical gravitational collapse in N dimensions

    NASA Astrophysics Data System (ADS)

    Goswami, Rituparno; Joshi, Pankaj S.

    2007-10-01

    We investigate here spherically symmetric gravitational collapse in a space-time with an arbitrary number of dimensions and with a general type I matter field, which is a broad class that includes most of the physically reasonable matter forms. We show that given the initial data for matter in terms of the initial density and pressure profiles at an initial surface t=ti from which the collapse evolves, there exist the rest of the initial data functions and classes of solutions of Einstein equations which we construct here, such that the space-time evolution goes to a final state which is either a black hole or a naked singularity, depending on the nature of initial data and evolutions chosen, and subject to validity of the weak energy condition. The results are discussed and analyzed in the light of the cosmic censorship hypothesis in black hole physics. The formalism here combines the earlier results on gravitational collapse in four dimensions in a unified treatment. Also the earlier work is generalized to higher-dimensional space-times to allow a study of the effect of the number of dimensions on the possible final outcome of the collapse in terms of either a black hole or naked singularity. No restriction is adopted on the number of dimensions, and other limiting assumptions such as self-similarity of space-time are avoided, in order to keep the treatment general. Our methodology allows us to consider to an extent the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse.

  1. The Transient Radio Sky

    NASA Astrophysics Data System (ADS)

    Keane, E. F.

    2010-11-01

    The high time-resolution radio sky represents unexplored astronomical territory where the discovery potential is high. In this thesis I have studied the transient radio sky, focusing on millisecond scales. As such, this work is concerned primarily with neutron stars, the mostpopulous member of the radio transient parameter space. In particular, I have studied the well known radio pulsars and the recently identified group of neutron stars which show erratic radio emission, known as RRATs, which show radio bursts every few minutes to every few hours. When RRATs burst onto the scene in 2006, it was thought that they represented a previously unknown, distinct class of sporadically emitting sources. The difficulty in their identification implies a large underlying population, perhaps larger than the radio pulsars. The first question investigated in this thesis was whether the large projected population of RRATs posed a problem, i.e. could the observed supernova rate account for so many sources. In addition to pulsars and RRATs, the various other known neutron star manifestations were considered, leading to the conclusion that distinct populations would result in a `birthrate problem'. Evolution between the classes could solve this problem -- the RRATs are not a distinct population ofneutron stars.Alternatively, perhaps the large projected population of RRATs is an overestimate. To obtain an improved estimate, the best approach is to find more sources. The Parkes Multi-beam Pulsar Survey, wherein the RRATs were initially identified, offered an opportunity to do just this. Abouthalf of the RRATs showing bursts during the survey were thought to have been missed, due to the deleterious effects of impulsive terrestrial interference signals. To remove these unwanted signals, so that we could identify the previously shrouded RRATs, we developed newinterference mitigation software and processing techniques. Having done this, the survey was completely re-processed, resulting in

  2. Tests of general relativity using Starprobe radio metric tracking data

    NASA Technical Reports Server (NTRS)

    Mease, K. D.; Anderson, J. D.; Wood, L. J.; White, L. K.

    1982-01-01

    The potential of a proposed spacecraft mission, called Starprobe, for testing general relativity and providing information on the interior structure and dynamics of the sun is investigated. Parametric, gravitational perturbation terms are derived which represent relativistic effects and effects due to spatial and temporal variations in the solar potential at a given radial distance. A covariance analysis based on Kalman filtering theory predicts the accuracies with which the free parameters in the perturbation terms can be estimated with radio metric tracking data through the process of trajectory reconstruction. It is concluded that Starprobe can contribute significant information on both the nature of gravitation and the structure and dynamics of the solar interior.

  3. Weight, gravitation, inertia, and tides

    NASA Astrophysics Data System (ADS)

    Pujol, Olivier; Lagoute, Christophe; Pérez, José-Philippe

    2015-11-01

    This paper deals with the factors that influence the weight of an object near the Earth's surface. They are: (1) the Earth's gravitational force, (2) the centrifugal force due to the Earth's diurnal rotation, and (3) tidal forces due to the gravitational field of the Moon and Sun, and other solar system bodies to a lesser extent. Each of these three contributions is discussed and expressions are derived. The relationship between weight and gravitation is thus established in a direct and pedagogical manner readily understandable by undergraduate students. The analysis applies to the Newtonian limit of gravitation. The derivation is based on an experimental (or operational) definition of weight, and it is shown that it coincides with the Earth’s gravitational force modified by diurnal rotation around a polar axis and non-uniformity of external gravitational bodies (tidal term). Two examples illustrate and quantify these modifications, respectively the Eötvös effect and the oceanic tides; tidal forces due to differential gravitation on a spacecraft and an asteroid are also proposed as examples. Considerations about inertia are also given and some comments are made about a widespread, yet confusing, explanation of tides based on a centrifugal force. Finally, the expression of the potential energy of the tide-generating force is established rigorously in the appendix.

  4. Gravitational wave astronomy: needle in a haystack.

    PubMed

    Cornish, Neil J

    2013-02-13

    A worldwide array of highly sensitive ground-based interferometers stands poised to usher in a new era in astronomy with the first direct detection of gravitational waves. The data from these instruments will provide a unique perspective on extreme astrophysical objects, such as neutron stars and black holes, and will allow us to test Einstein's theory of gravity in the strong field, dynamical regime. To fully realize these goals, we need to solve some challenging problems in signal processing and inference, such as finding rare and weak signals that are buried in non-stationary and non-Gaussian instrument noise, dealing with high-dimensional model spaces, and locating what are often extremely tight concentrations of posterior mass within the prior volume. Gravitational wave detection using space-based detectors and pulsar timing arrays bring with them the additional challenge of having to isolate individual signals that overlap one another in both time and frequency. Promising solutions to these problems will be discussed, along with some of the challenges that remain. PMID:23277598

  5. Collective Baryon Decay and Gravitational Collapse

    NASA Astrophysics Data System (ADS)

    Chapline, George; Barbieri, James

    2014-01-01

    While it is widely believed that the gravitational collapse of a sufficiently large mass will lead to a density singularity and an event horizon, we propose that this never happens when quantum effects are taken into account. In particular, we propose that when the conditions become ripe for the formation of a trapped surface, a quantum critical firewall sweeps over the collapsing body, transforming the nucleons in the collapsing matter into a lepton/photon gas together with droplets of a positive vacuum energy. This will happen regardless of the matter density at the time a trapped surface starts to form, and as a result, we predict that at least in all cases of gravitational collapse involving ordinary matter, a large fraction of the rest mass of the collapsing matter will be converted into a burst of neutrinos and γ-rays. We predict that the peak luminosity of these bursts is only weakly dependent on the mass of the collapsing object, and on the order of (ɛq/mPc2)1/4c5/G where ɛq is the mean energy of a nucleon parton and mP is the Planck mass. The duration of the bursts will depend on the mass of the collapsing object; in the case of stellar core collapse, we predict that the duration of both the neutrino and γ-ray bursts will be on the order of 10s.

  6. Gravitational wave astronomy: needle in a haystack.

    PubMed

    Cornish, Neil J

    2013-02-13

    A worldwide array of highly sensitive ground-based interferometers stands poised to usher in a new era in astronomy with the first direct detection of gravitational waves. The data from these instruments will provide a unique perspective on extreme astrophysical objects, such as neutron stars and black holes, and will allow us to test Einstein's theory of gravity in the strong field, dynamical regime. To fully realize these goals, we need to solve some challenging problems in signal processing and inference, such as finding rare and weak signals that are buried in non-stationary and non-Gaussian instrument noise, dealing with high-dimensional model spaces, and locating what are often extremely tight concentrations of posterior mass within the prior volume. Gravitational wave detection using space-based detectors and pulsar timing arrays bring with them the additional challenge of having to isolate individual signals that overlap one another in both time and frequency. Promising solutions to these problems will be discussed, along with some of the challenges that remain.

  7. Constraining the braneworld with gravitational wave observations.

    PubMed

    McWilliams, Sean T

    2010-04-01

    Some braneworld models may have observable consequences that, if detected, would validate a requisite element of string theory. In the infinite Randall-Sundrum model (RS2), the AdS radius of curvature, l, of the extra dimension supports a single bound state of the massless graviton on the brane, thereby reproducing Newtonian gravity in the weak-field limit. However, using the AdS/CFT correspondence, it has been suggested that one possible consequence of RS2 is an enormous increase in Hawking radiation emitted by black holes. We utilize this possibility to derive two novel methods for constraining l via gravitational wave measurements. We show that the EMRI event rate detected by LISA can constrain l at the approximately 1 microm level for optimal cases, while the observation of a single galactic black hole binary with LISA results in an optimal constraint of l < or = 5 microm. PMID:20481929

  8. Gravitational Polarization & The Schiff-Dessler Controversy

    NASA Astrophysics Data System (ADS)

    Morawice, Pawel; Yin, Ming; Wescott, Michael; Overcash, Dan; Datta, Timir

    2009-11-01

    The behavior of composite matter in external fields can be very reveling. The quantum mechanical problem of an electrically conducting material object (test mass) placed in a uniform (weak) gravitational field, g, was considered by many authors starting with Schiff [Phys. Rev. 151, 1067 (1966)]. Depending on the theoretical treatment opposing results of gravity induced (electric) field Eg have been reported. In the Schiff model [L.I. Schiff, PRB, 1, 4649 (1970)] Eg is predicted to be oriented anti-parallel (with reference to g). On the other hand it is found to be parallel in the more realistic elastic lattice model [A. J. Dessler et al, Phys.Rev, 168, 737, (1968); Edward Teller, PNAS, 74, 2664 (1977)]. Surprisingly, this contradiction has been largely overlooked by modern researchers. The preliminary results of an experimental study will be reported. Several interesting theoretical and technological implications will be suggested.

  9. Resonance and Radio

    ERIC Educational Resources Information Center

    Starrett, Malin J.

    2008-01-01

    The science and technology of radio receives little attention in contemporary education. This article discusses ways to explore the basic operating principles of radio. (Contains 4 figures, 3 footnotes, and 2 notes.)

  10. Composite weak bosons

    SciTech Connect

    Suzuki, M.

    1988-04-01

    Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.

  11. Sequential weak measurement

    SciTech Connect

    Mitchison, Graeme; Jozsa, Richard; Popescu, Sandu |||

    2007-12-15

    The notion of weak measurement provides a formalism for extracting information from a quantum system in the limit of vanishing disturbance to its state. Here we extend this formalism to the measurement of sequences of observables. When these observables do not commute, we may obtain information about joint properties of a quantum system that would be forbidden in the usual strong measurement scenario. As an application, we provide a physically compelling characterization of the notion of counterfactual quantum computation.

  12. An overview of gravitational physiology

    NASA Technical Reports Server (NTRS)

    Miquel, Jaime; Souza, Kenneth A.

    1991-01-01

    The focus of this review is on the response of humans and animals to the effects of the near weightless condition occurring aboard orbiting spacecraft. Gravity is an omnipresent force that has been a constant part of our lives and of the evolution of all living species. Emphasis is placed on the general mechanisms of adaptation to altered gravitational fields and vectors, i.e., both hypo- and hypergravity. A broad literature review of gravitational biology was conducted and the general state of our knowledge in this area is discussed. The review is specifically targeted at newcomers to the exciting and relatively new area of space and gravitational biology.

  13. Gravitation. [Book on general relativity

    NASA Technical Reports Server (NTRS)

    Misner, C. W.; Thorne, K. S.; Wheeler, J. A.

    1973-01-01

    This textbook on gravitation physics (Einstein's general relativity or geometrodynamics) is designed for a rigorous full-year course at the graduate level. The material is presented in two parallel tracks in an attempt to divide key physical ideas from more complex enrichment material to be selected at the discretion of the reader or teacher. The full book is intended to provide competence relative to the laws of physics in flat space-time, Einstein's geometric framework for physics, applications with pulsars and neutron stars, cosmology, the Schwarzschild geometry and gravitational collapse, gravitational waves, experimental tests of Einstein's theory, and mathematical concepts of differential geometry.

  14. Gravitational radiation quadrupole formula is valid for gravitationally interacting systems

    NASA Technical Reports Server (NTRS)

    Walker, M.; Will, C. M.

    1980-01-01

    An argument is presented for the validity of the quadrupole formula for gravitational radiation energy loss in the far field of nearly Newtonian (e.g., binary stellar) systems. This argument differs from earlier ones in that it determines beforehand the formal accuracy of approximation required to describe gravitationally self-interacting systems, uses the corresponding approximate equation of motion explicitly, and evaluates the appropriate asymptotic quantities by matching along the correct space-time light cones.

  15. Gravitational Stokes parameters. [for electromagnetic and gravitational radiation in relativity

    NASA Technical Reports Server (NTRS)

    Anile, A. M.; Breuer, R. A.

    1974-01-01

    The electromagnetic and gravitational Stokes parameters are defined in the general theory of relativity. The general-relativistic equation of radiative transfer for polarized radiation is then derived in terms of the Stokes parameters for both high-frequency electromagnetic and gravitational waves. The concept of Stokes parameters is generalized for the most general class of metric theories of gravity, where six (instead of two) independent states of polarization are present.

  16. Extragalactic Radio Sources

    ERIC Educational Resources Information Center

    Kellerman, Kenneth I.

    1973-01-01

    Discusses new problems arising from the growing observational data through radio telescope arrays, involving the origin of radio sources, apparent superluminal velocities, conversion of radio sources to relativistic particles, and the nature of compact opaque and extended transparent sources. New physics may be needed to answer these cosmological…

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

    SciTech Connect

    Brandao, C. S. S.; De Araujo, J. C. N. E-mail: jcarlos.dearaujo@inpe.br

    2012-05-01

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

  18. Dissipation of modified entropic gravitational energy through gravitational waves

    NASA Astrophysics Data System (ADS)

    de Matos, Clovis Jacinto

    2012-01-01

    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 Λ^{1/2}hbar G/c4˜9.27×10^{-105} seconds, which is much smaller than the Planck time t P =( ħG/ c 5)1/2˜5.38×10-44 seconds. This appears together with an absolute possible maximum value for Newtonian gravitational forces generated by matter Fg=32/30c7/Λ hbar G2˜ 3.84× 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˜1.21×1044 Newtons.

  19. The local radio-galaxy population at 20 GHz

    NASA Astrophysics Data System (ADS)

    Sadler, Elaine M.; Ekers, Ronald D.; Mahony, Elizabeth K.; Mauch, Tom; Murphy, Tara

    2014-02-01

    We have made the first detailed study of the high-frequency radio-source population in the local Universe, using a sample of 202 radio sources from the Australia Telescope 20 GHz (AT20G) survey identified with galaxies from the 6dF Galaxy Survey (6dFGS). The AT20G-6dFGS galaxies have a median redshift of z = 0.058 and span a wide range in radio luminosity, allowing us to make the first measurement of the local radio luminosity function at 20 GHz. Our sample includes some classical Fanaroff-Riley type I (FR I) and FR II radio galaxies, but most of the AT20G-6dFGS galaxies host compact (FR 0) radio active galactic nuclei which appear to lack extended radio emission even at lower frequencies. Most of these FR 0 sources show no evidence for relativistic beaming, and the FR 0 class appears to be a mixed population which includes young compact steep-spectrum and gigahertz peaked-spectrum radio galaxies. We see a strong dichotomy in the Wide-field Infrared Survey Explorer (WISE) mid-infrared colours of the host galaxies of FR I and FR II radio sources, with the FR I systems found almost exclusively in WISE `early-type' galaxies and the FR II radio sources in WISE `late-type' galaxies. The host galaxies of the flat- and steep-spectrum radio sources have a similar distribution in both K-band luminosity and WISE colours, though galaxies with flat-spectrum sources are more likely to show weak emission lines in their optical spectra. We conclude that these flat-spectrum and steep-spectrum radio sources mainly represent different stages in radio-galaxy evolution, rather than beamed and unbeamed radio-source populations.

  20. Faraday rotation due to quadratic gravitation

    NASA Astrophysics Data System (ADS)

    Chen, Yihan; Liu, Liping; Tian, Wen-Xiu

    2011-01-01

    The linearized field equations of quadratic gravitation in stationary space-time are written in quasi-Maxwell form. The rotation of the polarization plane for an electromagnetic wave propagating in the gravito-electromagnetic field caused by a rotating gravitational lens is discussed. The influences of the Yukawa potential in quadratic gravitation on the gravitational Faraday rotation are investigated.

  1. Gravitation toward Walls among Human Subjects

    ERIC Educational Resources Information Center

    Dabbs, James M., Jr.; Wheeler, Patricia A.

    1976-01-01

    In two studies, college students (N=34) in a classroom corridor who walked near the wall ("gravitators") were contrasted with those who walked near the center ("non-gravitators"). Gravitators were lower than non-gravitators on Autonomy and Defendence and appeared to be less responsive to other persons. (Author)

  2. Quantum Opportunities in Gravitational Wave Detectors

    SciTech Connect

    Mavalvala, Negris

    2012-03-14

    Direct observation of gravitational waves should open a new window into the Universe. Gravitational wave detectors are the most sensitive position meters ever constructed. The quantum limit in gravitational wave detectors opens up a whole new field of study. Quantum opportunities in gravitational wave detectors include applications of quantum optics techniques and new tools for quantum measurement on truly macroscopic (human) scales.

  3. Is There a Quad Problem Among Pptical Gravitational Lenses?

    SciTech Connect

    Oguri, Masamune

    2007-06-06

    Most of optical gravitational lenses recently discovered in the Sloan Digital Sky Survey Quasar Lens Search (SQLS) have two-images rather than four images, in marked contrast to radio lenses for which the fraction of four-image lenses (quad fraction) is quite high. We revisit the quad fraction among optical lenses by taking the selection function of the SQLS into account. We find that the current observed quad fraction in the SQLS is indeed lower than, but consistent with, the prediction of our theoretical model. The low quad fraction among optical lenses, together with the high quad fraction among radio lenses, implies that the quasar optical luminosity function has a relatively shallow faint end slope.

  4. Mutual distance dependence drives the observed jet-power-radio-luminosity scaling relations in radio galaxies

    NASA Astrophysics Data System (ADS)

    Godfrey, L. E. H.; Shabala, S. S.

    2016-02-01

    The kinetic power of radio jets is a quantity of fundamental importance to studies of the AGN feedback process and radio galaxy physics. A widely used proxy for jet power is the extended radio luminosity. A number of empirical methods have been used to calibrate a scaling relationship between jet power (Q) and radio luminosity (L) of the form log (Q) = βL log (L) + C. The regression slope has typically been found to be βL ˜ 0.7-0.8. Here we show that the previously reported scaling relations are strongly affected by the confounding variable, distance. We find that in a sample of FRI X-ray cavity systems, after accounting for the mutual distance dependence, the jet power and radio luminosity are only weakly correlated, with slope βL ≈ 0.3: significantly flatter than previously reported. We also find that in previously used samples of high-power sources, no evidence for an intrinsic correlation is present when the effect of distance is accounted for. Using a simple model we show that βL is expected to be significantly lower in samples of FRI radio galaxies than it is for FRIIs, due to the differing dynamics for these two classes of radio source. For FRI X-ray cavity systems the model predicts βL(FRI) ≳ 0.5 in contrast to FRII radio galaxies, for which βL(FRII) ≳ 0.8. We discuss the implications of our finding for studies of radio mode feedback, and radio galaxy physics.

  5. Gravitational energy sources in Jupiter

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.

    1973-01-01

    Gravitational sources of the intrinsic luminosity of Jupiter are examined in the context of current hydrogen-helium models. When no gravitational separation of matter occurs, the amount of heat which can be released over the remaining lifetime of the planet is necessarily limited by the size of its existing reservoir of thermal energy. This conclusion rests only on the assumption that its interior is relatively cold and degenerate. If gravitational unmixing occurs, the size of the thermal reservoir does not necessarily limit the heat output. If core formation occurs, for example, then the size of the core formed will be a limiting factor. The energy released with the formation of a helium core is computed for Jupiter. A core growth rate, averaged over several billion years, of 20 trillionths of Jupiter's mass per year is required if gravitational separation is to play a significant role in the thermal evolution.

  6. Relativistic Gravitational Experiments in Space

    NASA Technical Reports Server (NTRS)

    Hellings, Ronald W. (Editor)

    1989-01-01

    The results are summarized of a workshop on future gravitational physics space missions. The purpose of the workshop was to define generic technological requirements for such missions. NASA will use the results to direct its program of advanced technology development.

  7. Gravitational scattering of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  8. Gravitational Many-Body Problem

    SciTech Connect

    Makino, J.

    2008-04-29

    In this paper, we briefly review some aspects of the gravitational many-body problem, which is one of the oldest problems in the modern mathematical science. Then we review our GRAPE project to design computers specialized to this problem.

  9. Shearfree cylindrical gravitational collapse

    SciTech Connect

    Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.

    2009-09-15

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

  10. Persistent Gravitational Radiation from Glitching Pulsars

    NASA Astrophysics Data System (ADS)

    Melatos, A.; Douglass, J. A.; Simula, T. P.

    2015-07-01

    Quantum mechanical simulations of neutron star rotational glitches, triggered by vortex avalanches in the superfluid stellar interior, reveal that vortices pin nonaxisymmetrically to the crust during the intervals between glitches. Hence a glitching neutron star emits a persistent current quadrupole gravitational wave signal at the star’s rotation frequency, whose interglitch amplitude is constant and determined by the avalanche history since birth. The signal can be detected in principle by coherent searches planned for the Laser Interferometer Gravitational Wave Observatory (LIGO), whether or not a glitch occurs during the observation, if the power-law distribution of glitch sizes extends up to {{Δ }}{{{Ω }}}{max}/{{Ω }}≳ {10}-6{η }-1{({{Δ }}φ )}-1{({{Ω }}/{10}3 {rad} {{{s}}}-1)}-3(D/1 {kpc}) in the targeted object, where {{Δ }}{{{Ω }}}{max} and {{Δ }}φ are the largest angular velocity jump and avalanche opening angle, respectively, to have occurred in a glitch since birth, Ω is the angular velocity at present, η is the crustal fraction of the moment of inertia, and D is the distance from the Earth. A major caveat concerning detectability is whether the nonaxisymmetries observed in existing simulations with ≲ {10}3 vortices extrapolate to realistic neutron stars with ≳ {10}15 vortices. The arguments for and against extrapolation are discussed critically in the context of avalanche dynamics in self-organized critical systems, but the issue cannot be resolved without larger simulations and tighter observational limits on η {{Δ }}φ {{Δ }}{{{Ω }}}{max} from future LIGO (non)detections and radio timing campaigns.

  11. The renaissance of radio astronomy: towards the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Ferrari, C.

    2016-09-01

    In this paper, I will give a brief overview of the largest radio telescope in the world, the Square Kilometre Array (SKA). The history of this instrument, its development as a huge international project, as well as its main scientific goals, will be summarised. I will then focus on a particular science case by presenting how the first phase of the SKA (SKA1), whose observations are expected to start in the early 2020's, will change our radio view of the largest gravitationally bound structures of the Universe: galaxy clusters.

  12. `Weak A' phenotypes

    PubMed Central

    Cartron, J. P.; Gerbal, A.; Hughes-Jones, N. C.; Salmon, C.

    1974-01-01

    Thirty-five weak A samples including fourteen A3, eight Ax, seven Aend, three Am and three Ae1 were studied in order to determine their A antigen site density, using an IgG anti-A labelled with 125I. The values obtained ranged between 30,000 A antigen sites for A3 individuals, and 700 sites for the Ae1 red cells. The hierarchy of values observed made it possible to establish a quantitative relationship between the red cell agglutinability of these phenotypes measured under standard conditions, and their antigen site density. PMID:4435836

  13. Weakly broken galileon symmetry

    SciTech Connect

    Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Vernizzi, Filippo

    2015-09-01

    Effective theories of a scalar ϕ invariant under the internal galileon symmetryϕ→ϕ+b{sub μ}x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon’s quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.

  14. Weak decay of hypernuclei

    SciTech Connect

    Grace, R.

    1983-01-01

    The Moby Dick spectrometer (at BNL) in coincidence with a range spectrometer and a TOF neutron detector will be used to study the weak decay modes of /sup 12/C. The Moby Dick spectrometer will be used to reconstruct and tag events in which specific hypernuclear states are formed in the reaction K/sup -/ + /sup 12/C ..-->.. ..pi../sup -/ + /sup 12/C. Subsequent emission of decay products (pions, protons and neutrons) in coincidence with the fast forward pion will be detected in a time and range spectrometer, and a neutron detector.

  15. Weakly broken galileon symmetry

    SciTech Connect

    Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Vernizzi, Filippo E-mail: luca.santoni@sns.it E-mail: filippo.vernizzi@cea.fr

    2015-09-01

    Effective theories of a scalar φ invariant under the internal galileon symmetry φ→φ+b{sub μ} x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon's quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.

  16. Nuclear Quantum Gravitation - The Correct Theory

    NASA Astrophysics Data System (ADS)

    Kotas, Ronald

    2016-03-01

    Nuclear Quantum Gravitation provides a clear, definitive Scientific explanation of Gravity and Gravitation. It is harmonious with Newtonian and Quantum Mechanics, and with distinct Scientific Logic. Nuclear Quantum Gravitation has 10 certain, Scientific proofs and 21 more good indications. With this theory the Physical Forces are obviously Unified. See: OBSCURANTISM ON EINSTEIN GRAVITATION? http://www.santilli- Foundation.org/inconsistencies-gravitation.php and Einstein's Theory of Relativity versus Classical Mechanics http://www.newtonphysics.on.ca/einstein/

  17. Models of Uranium continuum radio emission

    NASA Technical Reports Server (NTRS)

    Romig, Joseph H.; Evans, David R.; Sawyer, Constance B.; Schweitzer, Andrea E.; Warwick, James W.

    1987-01-01

    Uranium continuum radio emission detected by the Voyager 2 Planetary Radio Astronomy experiment during the January 1986 encounter is considered. The continuum emissions comprised four components (equatorial emissions, anomaly emissions, strong nightside emissions, and weak nightside emissions) associated with different sources. The equatorial emissions appeared most prominently during the days before closest approach and extended from 40 kHz or below to about 120 kHz. The anomaly emissions were seen about 12 hours before closest approach and extended to about 250 kHz. The agreement found between Miranda's phase and strong radio emission at 20.4 kHz, just after closest approach, suggests intense dynamic activity on the Miranda L shell.

  18. Weak Gravitatational Lensing by Illustris-1 Galaxies

    NASA Astrophysics Data System (ADS)

    Brainerd, Tereasa G.; Koh, Patrick H.

    2016-06-01

    We compute the weak gravitational lensing signal of isolated, central galaxies obtained from the z=0.5 timestep of the ΛCDM Illustris-1 simulation. The galaxies have stellar masses ranging from 9.5 ≤ log10(M*/Msun) ≤ 11.0 and are located outside cluster and rich group environments. Although there is local substructure present in the form of small, luminous satellite galaxies, the central galaxies are the dominant objects within the virial radii (r200), and each central galaxy is at least 5 times brighter than any other luminous galaxy within the friends-of-friends halo. We compute the weak lensing signal within projected radii 0.05 < rp/r200 < 1.5 and investigate the degree to which the weak lensing signal is anisotropic. Since CDM halos are non-spherical, the weak lensing signal is expected to be anisotropic; however, the degree of anisotropy that is observed depends upon the symmetry axes that are used to define the geometry. The anisotropy is expected to be maximized when the major axis of the projected dark matter mass distribution is used to define the geomety. In practice in the observed universe, one must necessarily use the projected distribution of the luminous mass to define the geometry. If mass and light are not well-aligned, this results in a suppression of the weak lensing anistropy. Our initial analysis shows that the ellipticity of the projected dark matter halo is uncorrelated with the ellipticity of the projected stellar mass. That is ɛhalo ≠ f × ɛlight, where f is a constant multiplicative factor. In addition, in projection on the sky, the major axis of the dark matter mass is offset from that of the stellar mass by ˜40o on average. On scales rp ≤ 0.15 r200, the weak lensing anisotropy obtained when using the stellar mass to define the geometry is of order 7% and agrees well with the anisotropy obtained when using the dark matter mass to define the geometry. On scales rp ˜ r200, the anisotropy obtained when using the stellar mass to

  19. A Population of X-ray Weak Quasars: PHL 1811 Analogs at High Redshift

    NASA Astrophysics Data System (ADS)

    Wu, Jianfeng; Brandt, W. N.; Hall, P. B.; Gibson, R. R.; Richards, G. T.; Schneider, D. P.; Shemmer, O.; Just, D. W.; Schmidt, S. J.

    2011-09-01

    Luminous X-ray emission is considered to be a universal property of efficiently accreting supermassive black holes. However, there are a few notable examples of quasars emitting X-rays much more weakly by a factor of 10-100. We report X-ray observations of a sample of 10 high-redshift (z 2.2) type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. All of the eight radio-quiet PHL 1811 analogs, without exception, are notably X-ray weak by a mean factor of 13. These sources lack broad absorption lines and have blue UV/optical continua, suggesting they are intrinsically X-ray weak. However, their average X-ray spectrum appears to be harder than those of typical quasars, which may indicate the presence of heavy intrinsic X-ray absorption. Our radio-quiet PHL 1811 analogs support a connection between an X-ray weak spectral energy distribution and PHL 1811-like UV emission lines; this connection provides an economical way to identify X-ray weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the radio-quiet quasar population is estimated to be < 1.2%. Correlations between relative X-ray brightness and UV emission-line properties suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions. Observationally, radio-quiet PHL 1811 analogs appear to be a subset ( 30%) of radio-quiet weak-line quasars (WLQs). The existence of a subset of quasars in which high-ionization "shielding gas" covers most of the BELR, but little more than the BELR, could potentially unify the PHL 1811 analogs and WLQs.

  20. A study of the x ray environment of radio galaxies

    NASA Technical Reports Server (NTRS)

    Rhee, George F.; Burns, Jack O.; Owen, Frazer

    1993-01-01

    We are currently working on a program to use extensive x-ray and radio databases to investigate the relationship between extended radio emission and environment in clusters of galaxies. The radio galaxy morphology is determined using VLA imaging and the x-ray properties are determined from Einstein IPC images. This study is motivated by the hypothesis that the key to understanding radio galaxies lies in the local environment. To test this hypothesis we have studied the detailed relationship between galaxy radio emission and the x-ray morphology of their parent clusters. In this pilot study we have used 35 radio sources found in 27 clusters. We have determined the position angle of the x-ray and radio emission, and x-ray and radio luminosities. The x-ray position was taken to be the position of peak flux of the subclump containing the radio galaxy. The radio position was taken to be the position of the galaxy. We do not find a correlation between the x-ray and radio source position angle. This remains true when the sample is divided into subsamples according to radio morphology (wide angle tail, twin jet, narrow angle tail galaxies). We find a weak correlation between the radio source luminosity and the x-ray luminosity. We have computed the distance from the radio galaxy position to the center of the x-ray clump. We find a mean distance from the x-ray clump center of 0.16 Mpc for the radio galaxies in this sample. The mean distance to the nearest clump of x-ray emission is typically half the distance to the optical cluster center. We thus find strong evidence that radio galaxies are located very close to clumps of x-ray emission. These subclumps are not always affiliated with the central cluster x-ray emission. This supports our hypothesis that x-ray emission may provide a key to understanding radio galaxy morphology. We find evidence that radio galaxies occur in clusters that contain prominent substructures. Radio galaxies may thus provide an added diagnostic of

  1. The enigmatic T Tauri radio source

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen L.; Brown, Alexander

    1994-01-01

    We have analyzed eight high angular resolution images of the prototype low mass pre-main-sequence star T Tauri obtained with the Very Large Array between 1987 and 1990. Our objectives were to confirm a recent report that the radio emission is both variable and circularly polarized, to determine whether this behavior originates in the optical star or in the infrared source lying 0.6 sec to its south, and to identify possible emission mechanisms. No variability or circular polarization was detected in the weak (approximately equals 1 mJy) radio emission associated with the visible star, down to levels of approximately equals 10%. The observed flux can be accounted for by free-free emission from an ionized wind with a mass-loss rate M = 3.7 x 10(exp -8) solar mass yr(exp -1), but a more accurate determination of the spectral index is needed to test the validity of sperical wind models. In sharp contrast, the 3.6 cm emission of the infrared source is variable (approximately equals 4-7 mJy) on time scales less than or equal to 3 days and circularly polarized at low levels of approximately equals 3% - 5%. The polarization was left circular when detected during periods of low radio activity but changed to right circular during a radio outburst, similar to the reversals that have been seen in some RS CVn binary systems. The spectral index is negative during 'quiescence,'and we argue that the emission is nonthermal gyrosynchrotron radiation. The detection of magnetic radio activity in this optically invisible infrared source sparks new interest in clarifying its evolutionary status. Sensitive 3.6 cm images reveal weak emission extending approximately equals 1 sec west of the T Tau system that is probably associated with high-velocity shock-excited gas flowing toward HH-1555. We find no radio evidence for a putative third component north of the visible star.

  2. Constraining Source Redshift Distributions with Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Wittman, D.; Dawson, W. A.

    2012-09-01

    We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the shears around clusters can constrain the redshifts, assuming fixed cosmological parameters. This provides a check on photometric redshifts, independent of source spectral energy distribution properties and therefore free of confounding factors such as misidentification of spectral breaks. We find that ~40 massive (σ v = 1200 km s-1) cluster lenses are sufficient to determine the fraction of sources in each of six coarse redshift bins to ~11%, given weak (20%) priors on the masses of the highest-redshift lenses, tight (5%) priors on the masses of the lowest-redshift lenses, and only modest (20%-50%) priors on calibration and evolution effects. Additional massive lenses drive down uncertainties as N_lens^{-{1\\over 2}}, but the improvement slows as one is forced to use lenses further down the mass function. Future large surveys contain enough clusters to reach 1% precision in the bin fractions if the tight lens-mass priors can be maintained for large samples of lenses. In practice this will be difficult to achieve, but the method may be valuable as a complement to other more precise methods because it is based on different physics and therefore has different systematic errors.

  3. GRAVITATIONAL MICROLENSING BY THE ELLIS WORMHOLE

    SciTech Connect

    Abe, F.

    2010-12-10

    A method to calculate light curves of the gravitational microlensing of the Ellis wormhole is derived in the weak-field limit. In this limit, lensing by the wormhole produces one image outside the Einstein ring and another image inside. The weak-field hypothesis is a good approximation in Galactic lensing if the throat radius is less than 10{sup 11} km. The light curves calculated have gutters of approximately 4% immediately outside the Einstein ring crossing times. The magnification of the Ellis wormhole lensing is generally less than that of Schwarzschild lensing. The optical depths and event rates are calculated for the Galactic bulge and Large Magellanic Cloud fields according to bound and unbound hypotheses. If the wormholes have throat radii between 100 and 10{sup 7} km, are bound to the galaxy, and have a number density that is approximately that of ordinary stars, detection can be achieved by reanalyzing past data. If the wormholes are unbound, detection using past data is impossible.

  4. Wideband Observations of Radio Pulsars

    NASA Astrophysics Data System (ADS)

    Pennucci, Timothy T.

    2015-08-01

    Pulsars are exotic objects which have yielded a bounty of important astrophysical results. As rapidly rotating, highly magnetized neutron stars, pulsars' stable rotation and beamed radio emission enables their use as interstellar laboratory clocks. The extraordinary timing regularity of the millisecond pulsar (MSP) population permits some of the most precise measurements in astronomy. The discovery of MSPs raised the probability of directly detecting gravitational waves for the first time. Ongoing efforts by several pulsar timing array (PTA) collaborations compliment the ground- and space-based efforts of laser interferometers. One such PTA is the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). NANOGrav has recently employed a new set of wideband instruments to increase the sensitivity of their PTA, and the future of pulsar astronomy is moving towards progressively larger bandwidths. In this dissertation, we address the benefits and issues from adopting the new instrumentation, particularly for the scientific motivations of NANOGrav. We first develop a measurement technique for simultaneously obtaining pulse times-of-arrival (TOAs) and dispersion measures (DMs) using 2D models of evolving Gaussian components. We then apply the methodology broadly to a variety of pulsars, including a bright, test MSP in a globular cluster, the Galactic Center magnetar, and the entire suite of 37 MSPs from the NANOGrav 9-year data set. For a subset of these MSPs, we make targeted observations at specific orbital phases aimed at improving the timing models and constraining the Shapiro delay. With a few exceptions, we find positive or consistent timing results from the implementation of our first generation wideband timing protocol. Some highlights include: improved measurement uncertainties, mitigation of chromatic ISM effects, a reduction in the number of timing parameters and TOAs, signs of chromatic DMs, and at least one new pulsar mass.

  5. Strong gravitational lensing of gravitational waves in Einstein Telescope

    SciTech Connect

    Piórkowska, Aleksandra; Biesiada, Marek; Zhu, Zong-Hong E-mail: marek.biesiada@us.edu.pl

    2013-10-01

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

  6. Self-gravitational instability in magnetized finitely conducting viscoelastic fluid

    NASA Astrophysics Data System (ADS)

    Prajapati, R. P.; Chhajlani, R. K.

    2013-04-01

    The linear self-gravitational instability of finitely conducting, magnetized viscoelastic fluid is investigated using the modified generalized hydrodynamic (GH) model. A general dispersion relation is obtained with the help of linearized perturbation equations using the normal mode analysis and it is discussed for longitudinal and transverse modes of propagation. In longitudinal propagation, we find that Alfven mode is uncoupled with the gravitating mode. The Jeans criterion of instability is determined which depends upon shear viscosity and bulk viscosity while it is independent of magnetic field. The viscoelastic effects modify the fundamental Jeans criterion of gravitational instability. In transverse mode of propagation, the Alfven mode couples with the acoustic mode, compressional viscoelastic mode and gravitating mode. The growth rate of Jeans instability is compared in weakly coupled plasma (WCP) and strongly coupled plasma (SCP) which is larger for SCP in both the modes of propagations. The presence of finite electrical resistivity removes the effect of magnetic field in the condition of Jeans instability and expression of critical Jeans wavenumber. It is found that Mach number and shear viscosity has stabilizing while finite electrical resistivity has destabilizing influence on the growth rate of Jeans instability.

  7. Gravitational lensing by a rotating massive object in a plasma

    NASA Astrophysics Data System (ADS)

    Morozova, V. S.; Ahmedov, B. J.; Tursunov, A. A.

    2013-08-01

    We study gravitational lensing in the vicinity of a slowly rotating massive object surrounded by a plasma. We have studied two effects: (i) the influence of the frame dragging on the deflection angle of the light ray in the presence of plasma (ii) Faraday rotation of the polarization plane of the light. We derive the expression for the lensing angle in a non-diagonal space-time in the weak field regime in the presence of plasma and discuss it for the spacetime metric of the slowly rotating object. The obtained deflection angle depends on (i) the frequency of the electromagnetic wave, due to the dispersion properties of the plasma; (ii) the gravitational mass M; and (iii) the angular momentum J of the gravitational lens. We studied the influence of rotation of the gravitational lens on the magnification of brightness of the source star in the case of microlensing and have shown that it is negligibly small. For the completeness of our study the effect of the Faraday rotation of the polarization plane is considered.

  8. Planned BepiColombo Radio Science Investigations

    NASA Astrophysics Data System (ADS)

    Asmar, Sami; Iess, Luciano; Dehant, Veronique; Milani, Andrea; Tortora, Paolo

    The BepiColombo mission to Mercury has defined the investigations of the planetary interiors as well as tests of the theory of general relativity among its science objectives. Both of these objectives can be achieved using the tools and instrumentation of Radio Science. The investigations will provide detailed mapping of Mercury's gravity field, along with temporal variations due to tides, and important information about its deep internal structure. The global gravitational field along with the rotation state of the planet would enable improved constrains of whether the solid surface is decoupled from the inner core. The addition of altimetry enables the geophysical study of the crust, mantle, and impact basins. The global orbital solutions, obtained from precise radio metric data will lead to very accurate tests of General Relativity and other metric theories of gravity. The classical tests of the solar gravitational deflection and the precession of perihelion could significantly improve the measurement of several post-Newtonian parameters to levels nearing detection of possible violations of General Relativity. In spite of the uncertainty of the theoretical scenarios, the motivations for further tests of gravitational theories are stronger then ever: string theory, new cosmological observations, the hypotheses of dark matter and dark energy, all point to the need for a new and more profound understanding of the universe and its laws, including the laws of gravity. In order to achieve the scientific objectives in geophysics and fundamental physics, suitable radio frequency instrumentation for the Doppler and ranging observables for the spacecraft as well as ground stations. The target ranging accuracy of approximately 20 cm require the capability of transmitting and receiving at multiple frequencies to reduce plasma noise as well as larger modulation bandwidths. This paper describes experiments for probing space-time in the solar system with the Bepi

  9. POLARIZATION OF THE THERMAL RADIO EMISSION FROM OUTER SOLAR CORONA

    SciTech Connect

    Sastry, Ch. V.

    2009-06-01

    The Haselgrove equations for radio-ray propagation in an anisotropic medium are used to determine the degree of circular polarization (dcp) of the low-frequency thermal radio emission from the outer solar corona with a magnetic field. The variation of dcp with frequency and magnetic field strength is investigated. It is found that weak magnetic fields can be detected by measuring the dcp at low frequencies.

  10. How To Measure Gravitational Aberration?

    NASA Astrophysics Data System (ADS)

    Krizek, M.; Solcova, A.

    2007-08-01

    In 1905, Henri Poincaré predicted the existence of gravitational waves and assumed that their speed c[g] would be that of the speed of light c. If the gravitational aberration would also have the same magnitude as the aberration of light, we would observe several paradoxical phenomena. For instance, the orbit of two bodies of equal mass would be unstable, since two attractive forces arise that are not in line and hence form a couple. This tends to increase the angular momentum, period, and total energy of the system. This can be modelled by a system of ordinary differential equations with delay. A big advantage of computer simulation is that we can easily perform many test for various possible values of the speed of gravity [1]. In [2], Carlip showed that gravitational aberration in general relativity is almost cancelled out by velocity-dependent interactions. This means that rays of sunlight are not parallel to the attractive gravitational force of the Sun, i.e., we do not see the Sun in the direction of its attractive force, but slightly shifted about an angle less than 20``. We show how the actual value of the gravitational aberration can be obtained by measurement of a single angle at a suitable time instant T corresponding to the perihelion of an elliptic orbit. We also derive an a priori error estimate that expresses how acurately T has to be determined to attain the gravitational aberration to a prescribed tolerance. [1] M. Křížek: Numerical experience with the finite speed of gravitational interaction, Math. Comput. Simulation 50 (1999), 237-245. [2] S. Carlip: Aberration and the speed of gravity, Phys. Lett. A 267 (2000), 81-87.

  11. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  12. Gravitational-wave implications for structure formation: A second-order approach

    NASA Astrophysics Data System (ADS)

    Pazouli, Despoina; Tsagas, Christos G.

    2016-03-01

    Gravitational waves are propagating undulations in the spacetime fabric, which interact very weakly with their environment. In cosmology, gravitational-wave distortions are produced by most of the inflationary scenarios and their anticipated detection should open a new window to the early Universe. Motivated by the relative lack of studies on the potential implications of gravitational radiation for the large-scale structure of the Universe, we consider its coupling to density perturbations during the postrecombination era. We do so by assuming an Einstein-de Sitter background cosmology and by employing a second-order perturbation study. At this perturbative level and on superhorizon scales, we find that gravitational radiation adds a distinct and faster growing mode to the standard linear solution for the density contrast. Given the expected weakness of cosmological gravitational waves, however, the effect of the new mode is currently subdominant and it could start becoming noticeable only in the far future. Nevertheless, this still raises the intriguing possibility that the late-time evolution of large-scale density perturbations may be dictated by the long-range (the Weyl), rather than the local (the Ricci) component of the gravitational field.

  13. Weak lensing of large scale structure in the presence of screening

    SciTech Connect

    Tessore, Nicolas; Metcalf, R. Benton; Giocoli, Carlo E-mail: hans.winther@astro.ox.ac.uk E-mail: pedro.ferreira@physics.ox.ac.uk

    2015-10-01

    A number of alternatives to general relativity exhibit gravitational screening in the non-linear regime of structure formation. We describe a set of algorithms that can produce weak lensing maps of large scale structure in such theories and can be used to generate mock surveys for cosmological analysis. By analysing a few basic statistics we indicate how these alternatives can be distinguished from general relativity with future weak lensing surveys.

  14. Relationships between volcano gravitational spreading and magma intrusion

    NASA Astrophysics Data System (ADS)

    Delcamp, Audray; van Wyk de Vries, Benjamin; James, Mike R.; Gailler, L. S.; Lebas, E.

    2012-04-01

    Volcano spreading, with its characteristic sector grabens, is caused by outward flow of weak substrata due to gravitational loading. This process is now known to affect many present-day edifices. A volcano intrusive complex can form an important component of an edifice and may induce deformation while it develops. Such intrusions are clearly observed in ancient eroded volcanoes, like the Scottish Palaeocene centres, or in geophysical studies such as in La Réunion, or inferred from large calderas, such as in Hawaii, the Canaries or Galapagos volcanoes. Volcano gravitational spreading and intrusive complex emplacement may act simultaneously within an edifice. We explore the coupling and interactions between these two processes. We use scaled analogue models, where an intrusive complex made of Golden syrup is emplaced within a granular model volcano based on a substratum of a ductile silicone layer overlain by a brittle granular layer. We model specifically the large intrusive complex growth and do not model small-scale and short-lived events, such as dyke intrusion, that develop above the intrusive complex. The models show that the intrusive complex develops in continual competition between upward bulging and lateral gravity spreading. The brittle substratum strongly controls the deformation style, the intrusion shape and also controls the balance between intrusive complex spreading and ductile layer-related gravitational spreading. In the models, intrusive complex emplacement and spreading produce similar structures to those formed during volcano gravitational spreading alone (i.e. grabens, folds, en échelon fractures). Therefore, simple analysis of fault geometry and fault kinetic indicators is not sufficient to distinguish gravitational from intrusive complex spreading, except when the intrusive complex is eccentric from the volcano centre. However, the displacement fields obtained for (1) a solely gravitational spreading volcano and for (2) a gravitational

  15. Lossy compression of weak lensing data

    SciTech Connect

    Vanderveld, R. Ali; Bernstein, Gary M.; Stoughton, Chris; Rhodes, Jason; Massey, Richard; Dobke, Benjamin M.

    2011-07-12

    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 10-4. 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.

  16. Lossy compression of weak lensing data

    DOE PAGESBeta

    Vanderveld, R. Ali; Bernstein, Gary M.; Stoughton, Chris; Rhodes, Jason; Massey, Richard; Dobke, Benjamin M.

    2011-07-12

    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 cosmicmore » 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 10-4. 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.« less

  17. Gravitational Waves from Neutron Stars

    NASA Astrophysics Data System (ADS)

    Kokkotas, Konstantinos

    2016-03-01

    Neutron stars are the densest objects in the present Universe, attaining physical conditions of matter that cannot be replicated on Earth. These unique and irreproducible laboratories allow us to study physics in some of its most extreme regimes. More importantly, however, neutron stars allow us to formulate a number of fundamental questions that explore, in an intricate manner, the boundaries of our understanding of physics and of the Universe. The multifaceted nature of neutron stars involves a delicate interplay among astrophysics, gravitational physics, and nuclear physics. The research in the physics and astrophysics of neutron stars is expected to flourish and thrive in the next decade. The imminent direct detection of gravitational waves will turn gravitational physics into an observational science, and will provide us with a unique opportunity to make major breakthroughs in gravitational physics, in particle and high-energy astrophysics. These waves, which represent a basic prediction of Einstein's theory of general relativity but have yet to be detected directly, are produced in copious amounts, for instance, by tight binary neutron star and black hole systems, supernovae explosions, non-axisymmetric or unstable spinning neutron stars. The focus of the talk will be on the neutron star instabilities induced by rotation and the magnetic field. The conditions for the onset of these instabilities and their efficiency in gravitational waves will be presented. Finally, the dependence of the results and their impact on astrophysics and especially nuclear physics will be discussed.

  18. The Detection of Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Braccini, Stefano; Fidecaro, Francesco

    The detection of gravitational waves is challenging researchers since half a century. The relative precision required, 10^{-21}, is difficult to imagine, this is 10^{-5} the diameter of a proton over several kilometres, using masses of tens of kilograms, or picometres over millions of kilometres. A theoretical description of gravitational radiation and its effects on matter, all consequence of the general theory of relativity, is given. Then the astrophysical phenomena that are candidates of gravitational wave emission are discussed, considering also amplitudes and rates. The binary neutron star system PSR1913+16, which provided the first evidence for energy loss by gravitational radiation in 1975, is briefly discussed. Then comes a description of the experimental developments, starting with ground-based interferometers, their working principles and their most important sources of noise. The earth-wide network that is being built describes how these instruments will be used in the observation era. Several other detection techniques, such as space interferometry, pulsar timing arrays and resonant detectors, covering different bands of the gravitational wave frequency spectrum complete these lectures.

  19. Gravitational Effects on Signal Transduction

    NASA Technical Reports Server (NTRS)

    Sytkowski, Arthur J.

    1999-01-01

    An understanding of the mechanisms by which individual cells perceive gravity and how these cells transduce and respond to gravitational stimuli is critical for the development of long-term manned space flight experiments. We now propose to use a well-characterized model erythroid cell system and to investigate gravitational perturbations of its erythropoietin (Epo) signaling pathway and gene regulation. Cells will be grown at 1-G and in simulated microgravity in the NASA Rotating Wall Vessel bioreactor (RWV). Cell growth and differentiation, the Epo-receptor, the protein kinase C pathway to the c-myc gene, and the protein phosphatase pathway to the c-myb gene will be studied and evaluated as reporters of gravitational stimuli. The results of these experiments will have impact on the problems of 1) gravitational sensing by individual cells, and 2) the anemia of space flight. This ground-based study also will serve as a Space Station Development Study in gravitational effects on intracellular signal transduction.

  20. Radio source evolution

    NASA Astrophysics Data System (ADS)

    Perucho, M.

    2016-02-01

    Baldwin (1982) wrote that {``the distribution of sources in the radio luminosity, P, overall physical size, D, diagram''} could be considered as {``the radio astronomer's H-R diagram''}. However, unlike the case of stars, not only the intrinsic properties of the jets, but also those of the host galaxy and the intergalactic medium are relevant to explain the evolutionary tracks of radio radio sources. In this contribution I review the current status of our understanding of the evolution of radio sources from a theoretical and numerical perspective, using the P-D diagram as a framework. An excess of compact (linear size {≤ 10} kpc) sources could be explained by low-power jets being decelerated within the host galaxy, as shown by recent numerical simulations. Finally, I discuss the possible tracks that radio sources may follow within this diagram, and the physical processes that can explain the different tracks.

  1. The Sardinia Radio Telescope

    NASA Astrophysics Data System (ADS)

    Grueff, G.; Alvito, G.; Ambrosini, R.; Bolli, P.; D'Amico, N.; Maccaferri, A.; Maccaferri, G.; Morsiani, M.; Mureddu, L.; Natale, V.; Olmi, L.; Orfei, A.; Pernechele, C.; Poma, A.; Porceddu, I.; Rossi, L.; Zacchiroli, G.

    We describe the Sardinia Radio Telescope (SRT), a new general purpose, fully steerable antenna of the National Institute for Astrophysics. The radio telescope is under construction near Cagliari (Sardinia). With its large aperture (64m diameter) and its active surface, SRT is capable of operations up to ˜100GHz, it will contribute significantly to VLBI networks and will represent a powerful single-dish radio telescope for many science fields. The radio telescope has a Gregorian optical configuration with a supplementary beam-waveguide (BWG), which provides additional focal points. The Gregorian surfaces are shaped to minimize the spill-over and standing wave. After the start of the contract for the radio telescope structural and mechanical fabrication in 2003, in the present year the foundation construction will be completed. The schedule foresees the radio telescope inauguration in late 2006.

  2. On the consequences of the weak field approximation

    NASA Astrophysics Data System (ADS)

    Laubenstein, John

    2013-04-01

    General Relativity reduces to Newtonian gravity within the appropriate limit. But, what is that limit? The conventional response is that of the weak field approximation in which the gravitating source is weak and velocities are low. But, this is a far cry from a quantitative statement. In that regard, the weak field may be defined more quantitatively as one in which any error introduced is far beyond the level of precision required. Since the field can always be made incrementally weaker there is no limit as to the degree of precision that can be achieved. In this regard, GR reduces exactly to Newtonian gravity at the limit where velocity goes to zero. It is only out of convenience that we extend this to include those conditions where v << c with the argument that any error is arbitrarily small. However, in practice GR can be shown to reduce to an exact Newtonian expression at v > 0. How can this observation fit with the quantitative definition of the weak field? This paper explores the consequences of the weak field approximation and the fact that GR reduces directly to Newtonian gravity within the weak field as opposed to the more specific condition where v = zero.

  3. Asymmetric gravitational spreading - Analogue experiments on the Svecofennian orogen

    NASA Astrophysics Data System (ADS)

    Nikkilä, Kaisa; Korja, Annakaisa; Koyi, Hemin; Eklund, Olav

    2015-04-01

    Over-thickened orogenic crust may suffer from rheological, gravitational and topographical unbalancing resulting in discharging via gravitational spreading. If the thickened orogen is also hot, then increased temperature may reduce the viscosity of the crust that may induce large-scale horizontal flow. The effect of flow on the crustal architecture has previously been modeled with symmetric two-way spreading or asymmetric one- or two-way spreading (like channel flow) experiments. Most models do not take into account of the contrasting mechanical properties of the juxtaposed terranes. We have made analogue experiments to study gravitational one-way spreading and the interplay between two crustal blocks with contrasting rheological properties. The models are 3 cm thick replicas of 60 km thick crust. They have three horizontal layers representing strong lower, weak middle and brittle upper crust. The models have cuts to study the effect of inherited crustal-scale weakness zones. The experiments have been conducted within a large centrifuge in the Hans Ramberg Tectonic Laboratory at Uppsala University. The analogue models propose that asymmetric, unilateral flow has different effect on the contrasting crustal units, in both horizontal and vertical directions. The laterally heterogeneous crust flows towards the direction of extension, and it rotates and extends the pre-existing weakness zones. The weakness zones facilitate exhumation and they increase strain rate. The weakness zones split the crust into subblocks, which stretch individually and which may show signatures of compression or rotation. The changes in thickness of the model reflect changes in the layers, which may thin or thicken depending on the mechanical properties of crustal layers. A consequence of this the total amount of flattening is less than the model extension. The results are compared to geophysical and geological data from Precambrian Svecofennian orogen in Fennoscandia. The comparison suggest

  4. Interplanetary scintillation observations with the Cocoa Cross radio telescope

    NASA Technical Reports Server (NTRS)

    Cronyn, W. M.; Shawhan, S. D.; Erskine, F. T.; Huneke, A. H.; Mitchell, D. G.

    1976-01-01

    Physical and electrical parameters for the 34.3-MHz Cocoa Cross radio telescope are given. The telescope is dedicated to the determination of solar-wind characteristics in and out of the ecliptic plane through measurement of electron-density irregularity structure as determined from IPS (interplanetary scintillation) of natural radio sources. The collecting area (72,000 sq m), angular resolution (0.4 deg EW by 0.6 deg NS), and spatial extent (1.3 km EW by 0.8 km NS) make the telescope well suited for measurements of IPS index and frequency scale for hundreds of weak radio sources without serious confusion effects.

  5. Extended radio source in the center of M31

    SciTech Connect

    Hjellming, R.M.; Smarr, L.L.

    1982-06-01

    Radio observations of the central 1/sup 0/ x 1/sup 0/ region of the Andromeda Nebula (M31), made with the 1 km configuration of the NRAO VLA, show that at 1465 MHz the central radio source is nearly spherical and 2 kpc (10') in diameter, with a brightness distribution roughly proportional to exp(-R/1.'1), where R is the angular distance from the radio maximum located 20'' from the nucleus at the position angle of 70/sup 0/. The broad structure of this object may be due to a bulge population of many weak supernova remnants or to a cosmic-ray electron-dominated galactic wind.

  6. Spin gravitational resonance and graviton detection

    NASA Astrophysics Data System (ADS)

    Quach, James Q.

    2016-05-01

    We develop a gravitational analogue of spin magnetic resonance, called spin gravitational resonance, whereby a gravitational wave interacts with a magnetic field to produce a spin transition. In particular, an external magnetic field separates the energy spin states of a spin-1 /2 particle, and the presence of the gravitational wave produces a perturbation in the components of the magnetic field orthogonal to the gravitational-wave propagation. In this framework we test Dyson's conjecture that individual gravitons cannot be detected. Although we find no fundamental laws preventing single gravitons being detected with spin gravitational resonance, we show that it cannot be used in practice, in support of Dyson's conjecture.

  7. Modeling the Complete Gravitational Wave Spectrum of Neutron Star Mergers.

    PubMed

    Bernuzzi, Sebastiano; Dietrich, Tim; Nagar, Alessandro

    2015-08-28

    In the context of neutron star mergers, we study the gravitational wave spectrum of the merger remnant using numerical relativity simulations. Postmerger spectra are characterized by a main peak frequency f2 related to the particular structure and dynamics of the remnant hot hypermassive neutron star. We show that f(2) is correlated with the tidal coupling constant κ(2)^T that characterizes the binary tidal interactions during the late-inspiral merger. The relation f(2)(κ(2)^T) depends very weakly on the binary total mass, mass ratio, equation of state, and thermal effects. This observation opens up the possibility of developing a model of the gravitational spectrum of every merger unifying the late-inspiral and postmerger descriptions. PMID:26371635

  8. Gravitational scattering of zero-rest-mass plane waves

    NASA Technical Reports Server (NTRS)

    De Logi, W. K.; Kovacs, S. J., Jr.

    1977-01-01

    The Feyman-diagram technique is used to calculate the differential cross sections for the scattering of zero-rest-mass plane waves of spin 0, 1, and 2 by linearized Schwarzschild and Kerr geometries in the long-wavelength weak-field limit. It is found that the polarization of right (or left) circularly polarized electromagnetic waves is unaffected by the scattering process (i.e., helicity is conserved) and that the two helicity (polarization) states of the photon are scattered differently by the Kerr geometry. This coupling between the photon helicity and the angular momentum of the scatterer also leads to a partial polarization of unpolarized incident light. For gravitational waves, on the other hand, there is neither helicity conservation nor helicity-dependent scattering; the angular momentum of the scatterer has no polarizing effect on incident unpolarized gravitational waves.

  9. Lensing of 21-cm fluctuations by primordial gravitational waves.

    PubMed

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed. PMID:23003237

  10. One gravitational potential or two? Forecasts and tests.

    PubMed

    Bertschinger, Edmund

    2011-12-28

    The metric of a perturbed Robertson-Walker space-time is characterized by three functions: a scale-factor giving the expansion history and two potentials that generalize the single potential of Newtonian gravity. The Newtonian potential induces peculiar velocities and, from these, the growth of matter fluctuations. Massless particles respond equally to the Newtonian potential and to a curvature potential. The difference of the two potentials, called the gravitational slip, is predicted to be very small in general relativity, but can be substantial in modified gravity theories. The two potentials can be measured, and gravity tested on cosmological scales, by combining weak gravitational lensing or the integrated Sachs-Wolfe effect with galaxy peculiar velocities or clustering. PMID:22084285

  11. Modeling the Complete Gravitational Wave Spectrum of Neutron Star Mergers.

    PubMed

    Bernuzzi, Sebastiano; Dietrich, Tim; Nagar, Alessandro

    2015-08-28

    In the context of neutron star mergers, we study the gravitational wave spectrum of the merger remnant using numerical relativity simulations. Postmerger spectra are characterized by a main peak frequency f2 related to the particular structure and dynamics of the remnant hot hypermassive neutron star. We show that f(2) is correlated with the tidal coupling constant κ(2)^T that characterizes the binary tidal interactions during the late-inspiral merger. The relation f(2)(κ(2)^T) depends very weakly on the binary total mass, mass ratio, equation of state, and thermal effects. This observation opens up the possibility of developing a model of the gravitational spectrum of every merger unifying the late-inspiral and postmerger descriptions.

  12. Shadows (Mirages) Around Black Holes and Retro Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Zakharov, A. F.; Nucita, A. A.; Depaolis, F.; Ingrosso, G.

    Recently Holz & Wheeler [1] considered a very attracting possibility to detect retro-MACHOs, i.e. retro-images of the Sun by a Schwarzschild black hole. In this paper we discuss glories (mirages) formed near rapidly rotating Kerr black hole horizons and propose a procedure to measure masses and rotation parameters analyzing these forms of mirages (a detailed description of the problem is given in [2]). In some sense that is a manifestation of gravitational lens effect in the strong gravitational field near black hole horizon and a generalization of the retro-gravitational lens phenomenon. We analyze the case of a Kerr black hole rotating at arbitrary speed for some selected positions of a distant observer with respect to the equatorial plane of a Kerr black hole. Some time ago Falcke, Melia & Agol [3] suggested to search shadows at the Galactic Center. In this paper we present the boundaries for shadows calculated numerically. We also propose to use future radio interferometer RADIOASTRON facilities to measure shapes of mirages (glories) and to evaluate the black hole spin as a function of the position angle of a distant observer.

  13. The double quasar 0957+561: examination of the gravitational lens hypothesis using the very large array.

    PubMed

    Greenfield, P E; Roberts, D H; Burke, B F

    1980-05-01

    A full 12-hour synthesis at 6-centimeter wavelength with the Very Large Array confirms the major features previously reported for the double quasar 0957+561. In addition, the existence of radio jets apparently associated with both quasars is demonstrated. Gravitational lens models are now favored on the basis of recent optical observations, and the radio jets place severe constraints on such models. Further radio observations of the double quasar are needed to establish the expected relative time delay in variations between the images.

  14. STEM on the radio

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-10-01

    Looking for an Internet radio station focusing on programing about science, technology, engineering, and math (STEM)? The U.S. National Science Foundation (NSF) announced on 26 September the launch of Science360 Radio, which it says is the first Internet radio stream dedicated to STEM programing. Science360 includes more than 100 radio shows and podcasts that are available on the Web as well as on iPhone and Android devices. The shows originate from a variety of sources, including NSF, other U.S. government agencies, science organizations, universities, and media outlets. For more information, see http://science360.gov/files/.

  15. THE OPTIMAL GRAVITATIONAL LENS TELESCOPE

    SciTech Connect

    Surdej, J.; Hanot, C.; Sadibekova, T.; Delacroix, C.; Habraken, S.; Coleman, P.; Dominik, M.; Le Coroller, H.; Mawet, D.; Quintana, H.; Sluse, D.

    2010-05-15

    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.

  16. Cardiovascular Adjustments to Gravitational Stress

    NASA Technical Reports Server (NTRS)

    Blomqvist, C. Gunnar; Stone, H. Lowell

    1991-01-01

    The effects of gravity on the cardiovascular system must be taken into account whenever a hemodynamic assessment is made. All intravascular pressure have a gravity-dependent hydrostatic component. The interaction between the gravitational field, the position of the body, and the functional characteristics of the blood vessels determines the distribution of intravascular volume. In turn this distribution largely determines cardiac pump function. Multiple control mechanisms are activated to preserve optimal tissue perfusion when the magnitude of the gravitational field or its direction relative to the body changes. Humans are particularly sensitive to such changes because of the combination of their normally erect posture and the large body mass and blood volume below the level of the heart. Current aerospace technology also exposes human subjects to extreme variations in the gravitational forces that range from zero during space travel to as much an nine-times normal during operation of high-performance military aircraft. This chapter therefore emphasizes human physiology.

  17. Gravitational baryogenesis after anisotropic inflation

    NASA Astrophysics Data System (ADS)

    Fukushima, Mitsuhiro; Mizuno, Shuntaro; Maeda, Kei-ichi

    2016-05-01

    The gravitational baryogensis may not generate a sufficient baryon asymmetry in the standard thermal history of the Universe when we take into account the gravitino problem. Hence, it has been suggested that anisotropy of the Universe can enhance the generation of the baryon asymmetry through the increase of the time change of the Ricci scalar curvature. We study the gravitational baryogenesis in the presence of anisotropy, which is produced at the end of an anisotropic inflation. Although we confirm that the generated baryon asymmetry is enhanced compared with the original isotropic cosmological model, taking into account the constraint on the anisotropy by the recent CMB observations, we find that it is still difficult to obtain the observed baryon asymmetry only through the gravitational baryogenesis without suffering from the gravitino problem.

  18. Gravitational waves and multimessenger astronomy

    NASA Astrophysics Data System (ADS)

    Ricci, Fulvio

    2016-07-01

    It is widely expected that in the coming quinquennium the first gravitational wave signal will be directly detected. The ground-based advanced LIGO and Virgo detectors are being upgraded to a sensitivity level such that we expect to be measure a significant binary merger rate. Gravitational waves events are likely to be accompanied by electromagnetic counterparts and neutrino emission carrying complementary information to those associated to the gravitational signals. If it becomes possible to measure all these forms of radiation in concert, we will end up an impressive increase in the comprehension of the whole phenomenon. In the following we summarize the scientific outcome of the interferometric detectors in the past configuration. Then we focus on some of the potentialities of the advanced detectors once used in the new context of the multimessenger astronomy.

  19. Chirality and gravitational parity violation.

    PubMed

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented. PMID:25919812

  20. Chirality and gravitational parity violation.

    PubMed

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented.

  1. Radio data transmission for SCADA

    SciTech Connect

    Frasier, W.E. )

    1989-09-01

    Enron has used such wireless systems as meteor burst radio, 952 MHz multiple address radio, VSAT and L-band satellite, cellular radio and ACSB radio. The company's experience with meteor burst radio communications is discussed in this paper. It indicates good system reliability and consequently all back-up telephone lines have been removed from sites using this system.

  2. Recent Developments in Gravitation - Proceedings of the Relativity Meeting - 89

    NASA Astrophysics Data System (ADS)

    Verdaguer, E.; Garriga, J.; Céspedes, J.

    1990-10-01

    The Table of Contents for the full book PDF is as follows: * Foreword * I. INVITED LECTURES * Low Energy Effects of Quantum Gravity * Rigid Motion lnvariance of Newtonian and Einatein's Theories of General Relativity * General Relativity and the Early Universe * Computer Algebra and Exact Solutions of the Einstein Equations * Gravitational Waves * II. REVIEW TALKS * Classical Relativistic Particles with Spin * Testing Flux Conservative Methods in Numerical Relativity * Symmetries in General Relativity and the Problem of Symmetry Inheritance * Clifford Algebra Approach to Gravitation: Applications to Symmetries and to Twisting, Type-N Fields * Unusual Frames of the Space-Time * Massive Photon Modes in Q.E.D. and Abnormal e+ e- Pair Production * Repulsive Gravity: A Current State of Understanding * Physics versus Metaphysics in Collision between Plane Gravitational Waves * Primordial Black Holes and FRW Cosmology * What Does Morphological Segregation of Galaxies Tell Us about Galaxy Formation? * III. SHORT COMMUNICATIONS * A Demianski Cavity with Small Rotation Parameter in a Dust Universe with Cosmological Constant * Relation between Quasirigidity and Weak Rigidity in Weak Fields * Almost-Product Structures in Relativity * On the Solutions of Quantum Field Equations in Curved Space-Time * Perturbative Methods for Type D Space-Time * The Energy-Momentum Tensor of Two Perfect Fluids * Two Fluids Solutions of Einstein Equations * Gravitational Wave Detection: The Problem of Estimating a Signal's Arrival Time * Quantum Particles Produced during Cosmic String Formation * Electric Neutrality and the Jordan-Thiry Scalar Field * Why Do Spinors Appear in Relativity? * Variational Principles and Quantum Gravity * A Nelson Like Approach to Quantum Mechanics on a Maximally Symmetric Manifold * A Note on the Scalar Product in Relativistic Quantum Mechanics * On the Tolman Bondi Solution of Einstein's Equations. Numerical Applications * The Dirac Equation in Two Rectilinear

  3. Search for gravitational waves associated with the August 2006 timing glitch of the Vela pulsar

    SciTech Connect

    Abadie, J.; Abbott, B. P.; Abbott, R.; Adhikari, R.; Ajith, P.; Anderson, S. B.; Araya, M.; Aso, Y.; Ballmer, S.; Betzwieser, J.; Billingsley, G.; Black, E.; Blackburn, J. K.; Bork, R.; Brooks, A. F.; Cannon, K. C.; Cardenas, L.; Cepeda, C.; Chalermsongsak, T.; Chatterji, S.

    2011-02-15

    The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission. In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational-wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. No gravitational-wave detection candidate was found. We place Bayesian 90% confidence upper limits of 6.3x10{sup -21} to 1.4x10{sup -20} on the peak intrinsic strain amplitude of gravitational-wave ring-down signals, depending on which spherical harmonic mode is excited. The corresponding range of energy upper limits is 5.0x10{sup 44} to 1.3x10{sup 45} erg.

  4. Search for Gravitational Waves Associated with the August 2006 Timing Glitch of the Vela Pulsar

    NASA Technical Reports Server (NTRS)

    Camp, J. B.; Cannizzo, J.; Stroeer, A.

    2011-01-01

    The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission, In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational-wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. No gravitational-wave detection candidate was found. We place Bayesian 90% confidence upper limits of 6,3 x 10(exp -21) to 1.4 x 10(exp -20) on the peak: intrinsic strain amplitude of gravitational-wave ring-down signals, depending on which spherical harmonic mode is excited. The corresponding range of energy upper limits is 5.0 x 10(exp 44) to 1.3 x 10(exp 45) erg.

  5. RADIO AND X-RAY SHOCKS IN CLUSTERS OF GALAXIES

    SciTech Connect

    Hong, Sungwook E.; Kang, Hyesung; Ryu, Dongsu E-mail: hskang@pusan.ac.kr

    2015-10-10

    Radio relics detected in the outskirts of galaxy clusters are thought to trace radio-emitting relativistic electrons accelerated at cosmological shocks. In this study, using the cosmological hydrodynamic simulation data for the large-scale structure formation and adopting a diffusive shock acceleration (DSA) model for the production of cosmic-ray (CR) electrons, we construct mock radio and X-ray maps of simulated galaxy clusters that are projected in the sky plane. Various properties of shocks and radio relics, including the shock Mach number, radio spectral index, and luminosity, are extracted from the synthetic maps and compared with observations. A substantial fraction of radio and X-ray shocks identified in these maps involve multiple shock surfaces along lines of sight (LOSs), and the morphology of shock distributions in the maps depends on the projection direction. Among multiple shocks in a given LOS, radio observations tend to pick up stronger shocks with flatter radio spectra, while X-ray observations preferentially select weaker shocks with larger kinetic energy flux. As a result, in some cases the shock Mach numbers and locations derived from radio and X-ray observations could differ from each other. We also find that the distributions of the spectral index and radio power of the synthetic radio relics are somewhat inconsistent with those of observed real relics; a bit more radio relics have been observed closer to the cluster core and with steeper spectral indices. We suggest that the inconsistency could be explained if very weak shocks with M{sub s} ≲ 2 accelerate CR electrons more efficiently, compared with the DSA model adopted here.

  6. GRAVITATIONAL WAVES FROM STELLAR COLLAPSE

    SciTech Connect

    C. L. FRYER

    2001-01-01

    Stellar core-collapse plays an important role in nearly all facets of astronomy: cosmology (as standard candles), formation of compact objects, nucleosynthesis and energy deposition in galaxies. In addition, they release energy in powerful explosions of light over a range of energies, neutrinos, and the subject of this meeting, gravitational waves. Because of this broad range of importance, astronomers have discovered a number of constraints which can be used to help them understand the importance of stellar core-collapse as gravitational wave sources.

  7. Cosmologies with variable gravitational constant

    SciTech Connect

    Narkikar, J.V.

    1983-03-01

    In 1937 Dirac presented an argument, based on the socalled large dimensionless numbers, which led him to the conclusion that the Newtonian gravitational constant G changes with epoch. Towards the end of the last century Ernst Mach had given plausible arguments to link the property of inertia of matter to the large scale structure of the universe. Mach's principle also leads to cosmological models with a variable gravitational constant. Three cosmologies which predict a variable G are discussed in this paper both from theoretical and observational points of view.

  8. Testing the gravitational instability hypothesis?

    NASA Technical Reports Server (NTRS)

    Babul, Arif; Weinberg, David H.; Dekel, Avishai; Ostriker, Jeremiah P.

    1994-01-01

    We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability theory, implies that the observed large-scale structures and large-scale flows were produced by the action of gravity. This assumption is false, in that there exist nongravitational theories that pass the reconstruction tests and gravitational theories with certain forms of biased galaxy formation that fail them. Gravitational instability theory predicts specific correlations between large-scale velocity and mass density fields, but the same correlations arise in any model where (a) structures in the galaxy distribution grow from homogeneous initial conditions in a way that satisfies the continuity equation, and (b) the present-day velocity field is irrotational and proportional to the time-averaged velocity field. We demonstrate these assertions using analytical arguments and N-body simulations. If large-scale structure is formed by gravitational instability, then the ratio of the galaxy density contrast to the divergence of the velocity field yields an estimate of the density parameter Omega (or, more generally, an estimate of beta identically equal to Omega(exp 0.6)/b, where b is an assumed constant of proportionality between galaxy and mass density fluctuations. In nongravitational scenarios, the values of Omega or beta estimated in this way may fail to represent the true cosmological values. However, even if nongravitational forces initiate and shape the growth of structure, gravitationally induced accelerations can dominate the velocity field at late times, long after the action of any nongravitational impulses. The estimated beta approaches the true value in such cases, and in our numerical simulations the estimated beta values are reasonably accurate for both gravitational and nongravitational models. Reconstruction tests

  9. Particles, Fields, and Gravitation. Proceedings

    SciTech Connect

    Rembieli ski, J.

    1998-11-01

    These proceedings represent papers presented at the Conference on Particles, Fields, and Gravitation held in Lodz, Poland in April, 1998. The topics discussed included quantum deformations and noncommutative geometry, quantum mechanics, quantum and topological field theory, modern gravitation theory and geometrical methods in physics. Solvable and quasisolvable models were also disussed. The talks and the resulting papers provided a comprehensive coverage of the main aspects of contemporary theoretical and mathematical physics. The Conference was attended by more than 100 scientists from all over the world. There were 54 papers presented at the conference,out of which 1 paper has been abstracted for the Energy,Science and Technology database.(AIP)

  10. The gravitational field of Phobos

    SciTech Connect

    Chao, B.F.; Rubincam, D.P. )

    1989-08-01

    The external gravitational field produced by a rigid body of uniform density but irregular shape is formulated in terms of spherical harmonics. The formalism is applied to the Martian satellite Phobos. Based on a 3-dimensional shape model of Phobos by Duxbury, the gravitational coefficients up to degree and order 4 for a homogeneous Phobos are computed. In particular, the authors find J{sub 2} = 0.105. The in-plane liberation amplitude of a homogeneous Phobos is predicted to be 0.97{degree}, within the rather large uncertainty of the observed value of 0.78 {plus minus} 0.4{degree}.

  11. Dynamics of dissipative gravitational collapse

    SciTech Connect

    Herrera, L.; Santos, N.O.

    2004-10-15

    The Misner and Sharp approach to the study of gravitational collapse is extended to the dissipative case in, both, the streaming out and the diffusion approximations. The role of different terms in the dynamical equation are analyzed in detail. The dynamical equation is then coupled to a causal transport equation in the context of Israel-Stewart theory. The decreasing of the inertial mass density of the fluid, by a factor which depends on its internal thermodynamics state, is reobtained, at any time scale. In accordance with the equivalence principle, the same decreasing factor is obtained for the gravitational force term. Prospective applications of this result to some astrophysical scenarios are discussed.

  12. A POPULATION OF X-RAY WEAK QUASARS: PHL 1811 ANALOGS AT HIGH REDSHIFT

    SciTech Connect

    Wu Jianfeng; Brandt, W. N.; Schneider, Donald P.; Hall, Patrick B.; Gibson, Robert R.; Schmidt, Sarah J.; Richards, Gordon T.; Shemmer, Ohad; Just, Dennis W.

    2011-07-20

    We report the results from Chandra and XMM-Newton observations of a sample of 10 type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were identified by the Sloan Digital Sky Survey at high redshift (z {approx} 2.2); eight are radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811 analogs, without exception, are notably X-ray weak by a mean factor of {approx}13. These sources lack broad absorption lines and have blue UV/optical continua, supporting the hypothesis that they are intrinsically X-ray weak like PHL 1811 itself. However, their average X-ray spectrum appears to be harder than those of typical quasars, which may indicate the presence of heavy intrinsic X-ray absorption. Our sample of radio-quiet PHL 1811 analogs supports a connection between an X-ray weak spectral energy distribution and PHL 1811-like UV emission lines; this connection provides an economical way to identify X-ray weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the radio-quiet quasar population is estimated to be {approx}< 1.2%. We have investigated correlations between relative X-ray brightness and UV emission-line properties (e.g., C IV equivalent width and blueshift) for a sample combining our radio-quiet PHL 1811 analogs, PHL 1811 itself, and typical type 1 quasars. These correlation analyses suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions. Observationally, the radio-quiet PHL 1811 analogs appear to be a subset ({approx}30%) of radio-quiet weak-line quasars (WLQs). The existence of a subset of quasars in which high-ionization 'shielding gas' covers most of the broad emission-line region (BELR), but little more than the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two radio-intermediate PHL 1811 analogs are X

  13. A Population of X-Ray Weak Quasars: PHL 1811 Analogs at High Redshift

    NASA Astrophysics Data System (ADS)

    Wu, Jianfeng; Brandt, W. N.; Hall, Patrick B.; Gibson, Robert R.; Richards, Gordon T.; Schneider, Donald P.; Shemmer, Ohad; Just, Dennis W.; Schmidt, Sarah J.

    2011-07-01

    We report the results from Chandra and XMM-Newton observations of a sample of 10 type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were identified by the Sloan Digital Sky Survey at high redshift (z ≈ 2.2); eight are radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811 analogs, without exception, are notably X-ray weak by a mean factor of ≈13. These sources lack broad absorption lines and have blue UV/optical continua, supporting the hypothesis that they are intrinsically X-ray weak like PHL 1811 itself. However, their average X-ray spectrum appears to be harder than those of typical quasars, which may indicate the presence of heavy intrinsic X-ray absorption. Our sample of radio-quiet PHL 1811 analogs supports a connection between an X-ray weak spectral energy distribution and PHL 1811-like UV emission lines; this connection provides an economical way to identify X-ray weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the radio-quiet quasar population is estimated to be <~ 1.2%. We have investigated correlations between relative X-ray brightness and UV emission-line properties (e.g., C IV equivalent width and blueshift) for a sample combining our radio-quiet PHL 1811 analogs, PHL 1811 itself, and typical type 1 quasars. These correlation analyses suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions. Observationally, the radio-quiet PHL 1811 analogs appear to be a subset (≈30%) of radio-quiet weak-line quasars (WLQs). The existence of a subset of quasars in which high-ionization "shielding gas" covers most of the broad emission-line region (BELR), but little more than the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two radio-intermediate PHL 1811 analogs are X-ray bright. X-ray spectral

  14. Radio Telescopes Reveal Unseen Galactic Cannibalism

    NASA Astrophysics Data System (ADS)

    2008-06-01

    Radio-telescope images have revealed previously-unseen galactic cannibalism -- a triggering event that leads to feeding frenzies by gigantic black holes at the cores of galaxies. Astronomers have long suspected that the extra-bright cores of spiral galaxies called Seyfert galaxies are powered by supermassive black holes consuming material. However, they could not see how the material is started on its journey toward the black hole. Optical/Radio Comparison Visible-light (left) and radio (right) image of galaxy pair: Radio image shows gas streaming between galaxies. CREDIT: Kuo et al., NRAO/AUI/NSF Click on image for more graphics. One leading theory said that Seyfert galaxies have been disturbed by close encounters with neighboring galaxies, thus stirring up their gas and bringing more of it within the gravitational reach of the black hole. However, when astronomers looked at Seyferts with visible-light telescopes, only a small fraction showed any evidence of such an encounter. Now, new images of hydrogen gas in Seyferts made using the National Science Foundation's Very Large Array (VLA) radio telescope show the majority of them are, in fact, disturbed by ongoing encounters with neighbor galaxies. "The VLA lifted the veil on what's really happening with these galaxies," said Cheng-Yu Kuo, a graduate student at the University of Virginia. "Looking at the gas in these galaxies clearly showed that they are snacking on their neighbors. This is a dramatic contrast with their appearance in visible starlight," he added. The effect of the galactic encounters is to send gas and dust toward the black hole and produce energy as the material ultimately is consumed. Black holes, concentrations of matter so dense that not even light can escape their gravitational pull, reside at the cores of many galaxies. Depending on how rapidly the black hole is eating, the galaxy can show a wide range of energetic activity. Seyfert galaxies have the mildest version of this activity, while

  15. Merging Black Holes and Gravitational Waves

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2009-01-01

    This talk will focus on simulations of binary black hole mergers and the gravitational wave signals they produce. Applications to gravitational wave detection with LISA, and electronagnetic counterparts, will be highlighted.

  16. Gravitational Wave Astrophysics: Opening the New Frontier

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2011-01-01

    The gravitational wave window onto the universe is expected to open in 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum. Keywords: Gravitational wave astrophysics; gravitational radiation; gravitational wave detectors; black holes.

  17. The Gravitational Landscape of the Solar System

    ERIC Educational Resources Information Center

    van den Berg, Willem H.

    2008-01-01

    The Sun's gravitational influence is of course much greater than that of any of the planets. Just how much greater can be dramatically illustrated by plotting their combined gravitational potential on the same graph.

  18. The Radio Jove Project

    NASA Technical Reports Server (NTRS)

    Thieman, J. R.

    2010-01-01

    The Radio love Project is a hands-on education and outreach project in which students, or any other interested individuals or groups build a radio telescope from a kit, operate the radio telescope, transmit the resulting signals through the internet if desired, analyze the results, and share the results with others through archives or general discussions among the observers. Radio love is intended to provide an introduction to radio astronomy for the observer. The equipment allows the user to observe radio signals from Jupiter, the Sun, the galaxy, and Earth-based radiation both natural and man-made. The project was started through a NASA Director's Discretionary Fund grant more than ten years ago. it has continued to be carried out through the dedicated efforts of a group of mainly volunteers. Dearly 1500 kits have been distributed throughout the world. Participation can also be done without building a kit. Pre-built kits are available. Users can also monitor remote radio telescopes through the internet using free downloadable software available through the radiosky.com website. There have been many stories of prize-winning projects, inspirational results, collaborative efforts, etc. We continue to build the community of observers and are always open to new thoughts about how to inspire the observers to still greater involvement in the science and technology associated with Radio Jove.

  19. Film, Radio, and Television.

    ERIC Educational Resources Information Center

    Hardesty, Carolyn, Ed.

    1990-01-01

    This journal issue covers the history of film, radio, and television in Iowa. The first article, "When Pictures and Sound Came to Iowa," summarizes the origin of movies and radio and their early beginnings in Iowa. Using old photographs and measurement charts, the viewing, reading, and listening habits of young people in 1950 and 1958 are…

  20. Writing for Radio.

    ERIC Educational Resources Information Center

    Tupper, Marianna S.

    1995-01-01

    Describes a 24-hour commercial radio station simulation class project for eighth-grade language arts. Students wrote their own scripts, chose music and were disc jockeys on their own music and talk shows, and prepared news and traffic reports. Guest speakers from actual commercial radio came in to discuss issues such as advertising, censorship,…

  1. Frequencies for radio astronomy.

    PubMed

    Smith, F G

    1970-10-31

    At present the scope of research in radio astronomy is limited by the allocation of frequencies, some of which have to be shared with other radio services. When the International Telecommunications Union reconsiders all frequency allocations next year, astronomers are hoping for an improvement.

  2. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1984-12-25

    Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.

  3. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, Henry D.; Fugitt, Jock A.; Howard, Donald R.

    1984-01-01

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  4. Precursory singularities in spherical gravitational collapse

    NASA Astrophysics Data System (ADS)

    Lake, Kayll

    1992-05-01

    General conditions are developed for the formation of naked precursory ('shell-focusing') singularities in spherical gravitational collapse. These singularities owe their nakedness to the fact that the gravitational potential fails to be single valued prior to the onset of a true gravitational singularity. It is argued that they do not violate the spirit of cosmic censorship. Rather, they may well be an essentially generic feature of relativistic gravitational collapse.

  5. Radio Transients from Accretion-induced Collapse of White Dwarfs

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.

    2016-10-01

    We investigate observational properties of accretion-induced collapse (AIC) of white dwarfs (WDs) in radio frequencies. If AIC is triggered by accretion from a companion star, a dense circumstellar medium can be formed around the progenitor system. Then, the ejecta from AIC collide with the dense circumstellar medium, creating a strong shock. The strong shock can produce synchrotron emission that can be observed in radio frequencies. Even if AIC occurs as a result of WD mergers, we argue that AIC may cause fast radio bursts (FRBs) if a certain condition is satisfied. If AIC forms neutron stars (NSs) that are so massive that rotation is required to support themselves (i.e., supramassive NSs), the supramassive NSs may immediately lose their rotational energy by the r-mode instability and collapse to black holes. If the collapsing supramassive NSs are strongly magnetized, they may emit FRBs, as previously proposed. The AIC radio transients from single-degenerate systems may be detected in future radio transient surveys like the Very Large Array Sky Survey or the Square Kilometer Array transient survey. Because AIC has been proposed as a source of gravitational waves (GWs), GWs from AIC may be accompanied by radio-bright transients that can be used to confirm the AIC origin of observed GWs.

  6. How to test gravitation theories by means of gravitational-wave measurements

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.

    1974-01-01

    Gravitational-wave experiments are a potentially powerful tool for testing gravitation theories. Most theories in the literature predict rather different polarization properties for gravitational waves than are predicted by general relativity; and many theories predict anomalies in the propagation speeds of gravitational waves.

  7. Radio search for the pulsing X-ray source in Hercules.

    NASA Technical Reports Server (NTRS)

    Doxsey, R.; Rappaport, S.; Spencer, J.; Zaumen, W.; Murthy, G. T.

    1972-01-01

    The region of the celestial sphere near the pulsing X-ray source in Hercules (2U 1705+34) has been searched for radio emission with the NRAO three-element interferometer. The search was conducted during a period when the Hercules source was in its 27-day state of low X-ray luminosity. Four weak radio sources, which may be considered as candidates for the radio counterpart of this X-ray source, were detected.

  8. Gravitational Lenses in the Classroom

    ERIC Educational Resources Information Center

    Ros, Rosa M.

    2008-01-01

    It is not common to introduce current astronomy in school lessons. This article presents a set of experiments about gravitational lenses. It is normal to simulate them by means of computers, but it is very simple to simulate similar effects using a drinking glass full of liquid or using only the glass base. These are, of course, cheap and easy…

  9. Counteracting Gravitation In Dielectric Liquids

    NASA Technical Reports Server (NTRS)

    Israelsson, Ulf E.; Jackson, Henry W.; Strayer, Donald M.

    1993-01-01

    Force of gravity in variety of dielectric liquids counteracted by imposing suitably contoured electric fields. Technique makes possible to perform, on Earth, variety of experiments previously performed only in outer space and at great cost. Also used similarly in outer space to generate sort of artificial gravitation.

  10. Thought experiments on gravitational forces

    NASA Astrophysics Data System (ADS)

    Lynden-Bell, D.; Katz, Joseph

    2014-03-01

    Large contributions to the near closure of the Universe and to the acceleration of its expansion are due to the gravitation of components of the stress-energy tensor other than its mass density. To familiarize astronomers with the gravitation of these components we conduct thought experiments on gravity, analogous to the real experiments that our forebears conducted on electricity. By analogy to the forces due to electric currents we investigate the gravitational forces due to the flows of momentum, angular momentum and energy along a cylinder. Under tension the gravity of the cylinder decreases but the `closure' of the 3-space around it increases. When the cylinder carries a torque the flow of angular momentum along it leads to a novel helical interpretation of Levi-Civita's external metric and a novel relativistic effect. Energy currents give gravomagnetic effects in which parallel currents repel and antiparallel currents attract, though such effects must be added to those of static gravity. The gravity of beams of light give striking illustrations of these effects and a re-derivation of light bending via the gravity of the light itself. Faraday's experiments lead us to discuss lines of force of both gravomagnetic and gravity fields. A serious conundrum arises if Landau and Lifshitz's definition of gravitational force is adopted.

  11. Normalization of Gravitational Acceleration Models

    NASA Technical Reports Server (NTRS)

    Eckman, Randy A.; Brown, Aaron J.; Adamo, Daniel R.

    2011-01-01

    Unlike the uniform density spherical shell approximations of Newton, the con- sequence of spaceflight in the real universe is that gravitational fields are sensitive to the nonsphericity of their generating central bodies. The gravitational potential of a nonspherical central body is typically resolved using spherical harmonic approximations. However, attempting to directly calculate the spherical harmonic approximations results in at least two singularities which must be removed in order to generalize the method and solve for any possible orbit, including polar orbits. Three unique algorithms have been developed to eliminate these singularities by Samuel Pines [1], Bill Lear [2], and Robert Gottlieb [3]. This paper documents the methodical normalization of two1 of the three known formulations for singularity-free gravitational acceleration (namely, the Lear [2] and Gottlieb [3] algorithms) and formulates a general method for defining normalization parameters used to generate normalized Legendre Polynomials and ALFs for any algorithm. A treatment of the conventional formulation of the gravitational potential and acceleration is also provided, in addition to a brief overview of the philosophical differences between the three known singularity-free algorithms.

  12. Caution: Strong Gravitational Field Present

    ERIC Educational Resources Information Center

    Reif, Marc

    2014-01-01

    I came up with a new way to introduce the concept of a constant gravitational field near the surface of the Earth. I made "g-field detectors" (see Fig. 1 ) and suspended them by strings from the ceiling in a regular spacing. The detectors are cardstock arrows with a hole punched out of them and the letter "g" in the center.

  13. Challenges in nonlinear gravitational clustering

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Thanu

    2006-04-01

    This article addresses some issues related to the statistical description of gravitating systems in an expanding backgrounds. In particular, I describe (a) how the nonlinear 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) what are the asymptotic characteristics of gravitational clustering that are independent of the initial conditions. The analysis uses a new approach based on an integro-differential equation for the evolution of the gravitational potential in the Fourier space. I show how this equation allows one to understand several aspects of nonlinear gravitational clustering and provides insight in to the transfer of power from one scale to another through nonlinear mode coupling. 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. To cite this article: T. Padmanabhan, C. R. Physique 7 (2006).

  14. Neutrino mass and dark energy from weak lensing.

    PubMed

    Abazajian, Kevork N; Dodelson, Scott

    2003-07-25

    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 deg(2) survey, we find that the expected (1-sigma) 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. PMID:12906650

  15. Dynamics of dust in the sheath of weakly electronegative plasmas

    SciTech Connect

    Wang Zhengxiong; Wang Xiaogang; Liu Jinyuan; Liu Yue

    2005-01-15

    The dynamics of dust in the sheath of weakly electronegative plasmas are investigated with the single dust model as well as the self-consistently variable dust charge. It is shown that when the dust particles enter the sheath region from the sheath edge with different initial velocities they may display different motion states: levitation in the sheath, returning from the sheath edge, and traversing the sheath region, under action of electrostatic, gravitational, ion-drag, and neutral collision forces. Furthermore, the electronegativity also plays an important role in the dust particle motion states in the sheath besides affecting the distributions of the spatial potential and the charging of the dust particles.

  16. Anatomy of gravitationally deformed slopes

    NASA Astrophysics Data System (ADS)

    Chigira, Masahiro; Yamasaki, Shintaro; Hariyama, Takehiro

    2010-05-01

    Deep-seated gravitational slope deformation is the deformation of rocks as well as slope surfaces, but the internal structures have not been well observed and described before. This is mainly due to the difficulty in obtaining undisturbed samples from underground. We analyzed the internal deformational structures of gravitationally deformed slopes by using high quality drilled cores obtained by hybrid drilling technique, which has been recently developed and can recover very fragile materials that could not be taken by the conventional drilling techniques. Investigated slopes were gravitationally deformed out-facing slopes of pelitic schist and shale. The slope surfaces showed deformational features of small steps, depressions, knobs, and linear depressions, but had no major main scarp and landslide body with well-defined outline. This is indicative of slow, deep-seated gravitational deformation. Most of these small deformational features are hidden by vegetations, but they are detected by using airborne laser scanner. Drilled cores showed that the internal deformation is dominated by the slip and tearing off along foliations. Slippage along foliations is conspicuous in pelitic schist: Pelitic schist is sheared, particularly along black layers, which are rich in graphite and pyrite. Graphite is known to be a solid lubricant in material sciences, which seems to be why shearing occurs along the black layers. Rock mass between two slip layers is sheared, rotated, fractured, and pulverized; undulation of bedding or schistosity could be the nucleation points of fracturing. Tearing off along foliations is also the major deformation mode, which forms jagged morphology of rock fragments within shear zones. Rock fragments with jagged surface are commonly observed in "gouge", which is very different from tectonic gouge. This probably reflects the low confining pressures during their formation. Microscopic to mesoscopic openings along fractures are commonly observed with

  17. On the Cauchy problems for polymer flooding with gravitation

    NASA Astrophysics Data System (ADS)

    Shen, Wen

    2016-07-01

    We study two systems of conservation laws for polymer flooding in secondary oil recovery, one with gravitation force and one without. For each model, we prove global existence of weak solutions for the Cauchy problems, under rather general assumptions on the flux functions. Approximate solutions are constructed through a front tracking algorithm, and compactness is achieved through the bound on suitably defined wave strengths. As the main technical novelty, we introduce some new nonlinear functionals that yield a uniform bound on the total variation of the flux function.

  18. Fast Radio Bursts and Their Gamma-Ray or Radio Afterglows as Kerr-Newman Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Liu, Tong; Romero, Gustavo E.; Liu, Mo-Lin; Li, Ang

    2016-07-01

    Fast radio bursts (FRBs) are radio transients lasting only about a few milliseconds. They seem to occur at cosmological distances. We propose that these events can originate in the collapse of the magnetospheres of Kerr-Newman black holes (KNBHs). We show that the closed orbits of charged particles in the magnetospheres of these objects are unstable. After examining the dependencies on the specific charge of the particle and the spin and charge of the KNBH, we conclude that the resulting timescale and radiation mechanism fit well with extant observations of FRBs. Furthermore, we argue that the merger of a KNBH binary is a plausible central engine for the potential gamma-ray or radio afterglow following certain FRBs and can also account for gravitational wave (GW) events like GW 150914. Our model leads to predictions that can be tested by combined multi-wavelength electromagnetic and GW observations.

  19. Fast Radio Bursts and Their Gamma-Ray or Radio Afterglows as Kerr–Newman Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Liu, Tong; Romero, Gustavo E.; Liu, Mo-Lin; Li, Ang

    2016-07-01

    Fast radio bursts (FRBs) are radio transients lasting only about a few milliseconds. They seem to occur at cosmological distances. We propose that these events can originate in the collapse of the magnetospheres of Kerr–Newman black holes (KNBHs). We show that the closed orbits of charged particles in the magnetospheres of these objects are unstable. After examining the dependencies on the specific charge of the particle and the spin and charge of the KNBH, we conclude that the resulting timescale and radiation mechanism fit well with extant observations of FRBs. Furthermore, we argue that the merger of a KNBH binary is a plausible central engine for the potential gamma-ray or radio afterglow following certain FRBs and can also account for gravitational wave (GW) events like GW 150914. Our model leads to predictions that can be tested by combined multi-wavelength electromagnetic and GW observations.

  20. PHL 1811 Analogs: A Population of X-ray Weak Quasars

    NASA Astrophysics Data System (ADS)

    Wu, J.; Brandt, W. N.; Hall, P. B.; Gibson, R. R.; Richards, G. T.; Schneider, D. P.; Shemmer, O.; Just, D. W.; Schmidt, S. J.

    2012-08-01

    We report on a population of X-ray weak quasars with UV emission-line properties similar to those of the remarkable quasar PHL 1811. All radio-quiet PHL 1811 analogs are notably X-ray weak by a mean factor of ≍ 13, with hints of heavy X-ray absorption. Correlations between the X-ray weakness and UV emission-line properties suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions (BELRs). We propose an AGN geometry that can potentially unify the PHL 1811 analogs and the general population of weak-line quasars.

  1. Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network.

    PubMed

    Aasi, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J S; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Augustus, H; Aulbert, C; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Baune, C; Bavigadda, V; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Biwer, C; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Calderón Bustillo, J; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castaldi, G; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P-F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J-P; Countryman, S; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Croce, R P; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Cutler, C; Dahl, K; Dal Canton, T; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; DeBra, D; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Dolique, V; Dominguez, E; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H-B; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fazi, D; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J-D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J R; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Gendre, B; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C J; Gushwa, K; Gustafson, E K; Gustafson, R; Ha, J; Hall, E D; Hamilton, W; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C-J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Holt, K; Hopkins, P; Horrom, T; Hoske, D; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Huerta, E; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Idrisy, A; Ingram, D R; Inta, R; Islas, G; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Haris, K; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N G; Kim, N; Kim, S; Kim, Y-M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, A; Kumar, D Nanda; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Lam, P K; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, J; Lee, P J; Leonardi, M; Leong, J R; Leonor, I; Le Roux, A; Leroy, N; Letendre, N; Levin, Y; Levine, B; Lewis, J; Li, T G F; Libbrecht, K; Libson, A; Lin, A C; Littenberg, T B; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lopez, E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Lubinski, M J; Lück, H; Lundgren, A P; Ma, Y; Macdonald, E P; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R; Mageswaran, M; Maglione, C; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mangini, N M; Mansell, G; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Martinelli, L; Martynov, D; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Matichard, F; Matone, L; Mavalvala, N; May, G; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McIver, J; McLin, K; Meacher, D; Meadors, G D; Mehmet, M; Meidam, J; Meinders, M; Melatos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C; Meyer, M S; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Mikhailov, E E; Milano, L; Miller, J; Minenkov, Y; Mingarelli, C M F; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moe, B; Moggi, A; Mohan, M; Mohapatra, S R P; Moraru, D; Moreno, G; Morgado, N; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Mukherjee, S; Mullavey, A; Munch, J; Murphy, D; Murray, P G; Mytidis, A; Nagy, M F; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nelemans, G; Neri, I; Neri, M; Newton, G; Nguyen, T; Nielsen, A B; Nissanke, S; Nitz, A H; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Ochsner, E; O'Dell, J; Oelker, E; Oh, J J; Oh, S H; Ohme, F; Omar, S; Oppermann, P; Oram, R; O'Reilly, B; Ortega, W; O'Shaughnessy, R; Osthelder, C; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Padilla, C; Pai, A; Palashov, O; Palomba, C; Pan, H; Pan, Y; Pankow, C; Paoletti, F; Papa, M A; Paris, H; Pasqualetti, A; Passaquieti, R; Passuello, D; Pedraza, M; Pele, A; Penn, S; Perreca, A; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pinard, L; Pinto, I M; Pitkin, M; Poeld, J; Poggiani, R; Poteomkin, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S; Prestegard, T; Price, L R; Prijatelj, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qin, J; Quetschke, V; Quintero, E; Quitzow-James, R; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Raja, S; Rajalakshmi, G; Rakhmanov, M; Ramet, C; Ramirez, K; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Recchia, S; Reed, C M; Regimbau, T; Reid, S; Reitze, D H; Reula, O; Rhoades, E; Ricci, F; Riesen, R; Riles, K; Robertson, N A; Robinet, F; Rocchi, A; Roddy, S B; Rolland, L; Rollins, J G; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Salemi, F; Sammut, L; Sandberg, V; Sanders, J R; Sankar, S; Sannibale, V; Santiago-Prieto, I; Saracco, E; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Savage, R; Scheuer, J; Schilling, R; Schilman, M; Schmidt, P; Schnabel, R; Schofield, R M S; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Shaddock, D A; Shah, S; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Shoemaker, D H; Sidery, T L; Siellez, K; Siemens, X; Sigg, D; Simakov, D; Singer, A; Singer, L; Singh, R; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, R J E; Smith-Lefebvre, N D; Son, E J; Sorazu, B; Souradeep, T; Staley, A; Stebbins, J; Steinke, M; Steinlechner, J; Steinlechner, S; Stephens, B C; Steplewski, S; Stevenson, S; Stone, R; Stops, D; Strain, K A; Straniero, N; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Susmithan, S; Sutton, P J; Swinkels, B; Tacca, M; Talukder, D; Tanner, D B; Tao, J; Tarabrin, S P; Taylor, R; Tellez, G; Thirugnanasambandam, M P; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Travasso, F; Traylor, G; Tse, M; Tshilumba, D; Tuennermann, H; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Beuzekom, M; van den Brand, J F J; Van Den Broeck, C; van der Sluys, M V; van Heijningen, J; van Veggel, A A; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vincent-Finley, R; Vinet, J-Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Vousden, W D; Vyachanin, S P; Wade, A R; Wade, L; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, M; Wang, X; Ward, R L; Was, M; Weaver, B; Wei, L-W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; White, D J; Whiting, B F; Wiesner, K; Wilkinson, C; Williams, K; Williams, L; Williams, R; Williams, T D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Wolovick, N; Worden, J; Wu, Y; Yablon, J; Yakushin, I; Yam, W; Yamamoto, H; Yancey, C C; Yang, H; Yoshida, S; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J-P; Zhang, Fan; Zhang, L; Zhao, C; Zhu, H; Zhu, X J; Zucker, M E; Zuraw, S; Zweizig, J; Aptekar, R L; Atteia, J L; Cline, T; Connaughton, V; Frederiks, D D; Golenetskii, S V; Hurley, K; Krimm, H A; Marisaldi, M; Pal'shin, V D; Palmer, D; Svinkin, D S; Terada, Y; von Kienlin, A

    2014-07-01

    We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors. PMID:25032916

  2. Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by the Interplanetary Network

    NASA Technical Reports Server (NTRS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Blackbum, L.; Camp, J. B.; Gehrels, N.; Graff, P. B.; Slutsky, J.; Cline, T.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.

    2014-01-01

    We present the results of a search for gravitational waves associated with 223 gamma ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(exp-2) solar mass c(exp 2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

  3. Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network.

    PubMed

    Aasi, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J S; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Augustus, H; Aulbert, C; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Baune, C; Bavigadda, V; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Biwer, C; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Calderón Bustillo, J; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castaldi, G; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P-F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J-P; Countryman, S; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Croce, R P; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Cutler, C; Dahl, K; Dal Canton, T; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; DeBra, D; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Dolique, V; Dominguez, E; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H-B; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fazi, D; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J-D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J R; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Gendre, B; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C J; Gushwa, K; Gustafson, E K; Gustafson, R; Ha, J; Hall, E D; Hamilton, W; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C-J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Holt, K; Hopkins, P; Horrom, T; Hoske, D; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Huerta, E; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Idrisy, A; Ingram, D R; Inta, R; Islas, G; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Haris, K; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N G; Kim, N; Kim, S; Kim, Y-M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, A; Kumar, D Nanda; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Lam, P K; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, J; Lee, P J; Leonardi, M; Leong, J R; Leonor, I; Le Roux, A; Leroy, N; Letendre, N; Levin, Y; Levine, B; Lewis, J; Li, T G F; Libbrecht, K; Libson, A; Lin, A C; Littenberg, T B; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lopez, E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Lubinski, M J; Lück, H; Lundgren, A P; Ma, Y; Macdonald, E P; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R; Mageswaran, M; Maglione, C; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mangini, N M; Mansell, G; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Martinelli, L; Martynov, D; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Matichard, F; Matone, L; Mavalvala, N; May, G; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McIver, J; McLin, K; Meacher, D; Meadors, G D; Mehmet, M; Meidam, J; Meinders, M; Melatos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C; Meyer, M S; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Mikhailov, E E; Milano, L; Miller, J; Minenkov, Y; Mingarelli, C M F; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moe, B; Moggi, A; Mohan, M; Mohapatra, S R P; Moraru, D; Moreno, G; Morgado, N; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Mukherjee, S; Mullavey, A; Munch, J; Murphy, D; Murray, P G; Mytidis, A; Nagy, M F; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nelemans, G; Neri, I; Neri, M; Newton, G; Nguyen, T; Nielsen, A B; Nissanke, S; Nitz, A H; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Ochsner, E; O'Dell, J; Oelker, E; Oh, J J; Oh, S H; Ohme, F; Omar, S; Oppermann, P; Oram, R; O'Reilly, B; Ortega, W; O'Shaughnessy, R; Osthelder, C; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Padilla, C; Pai, A; Palashov, O; Palomba, C; Pan, H; Pan, Y; Pankow, C; Paoletti, F; Papa, M A; Paris, H; Pasqualetti, A; Passaquieti, R; Passuello, D; Pedraza, M; Pele, A; Penn, S; Perreca, A; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pinard, L; Pinto, I M; Pitkin, M; Poeld, J; Poggiani, R; Poteomkin, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S; Prestegard, T; Price, L R; Prijatelj, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qin, J; Quetschke, V; Quintero, E; Quitzow-James, R; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Raja, S; Rajalakshmi, G; Rakhmanov, M; Ramet, C; Ramirez, K; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Recchia, S; Reed, C M; Regimbau, T; Reid, S; Reitze, D H; Reula, O; Rhoades, E; Ricci, F; Riesen, R; Riles, K; Robertson, N A; Robinet, F; Rocchi, A; Roddy, S B; Rolland, L; Rollins, J G; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Salemi, F; Sammut, L; Sandberg, V; Sanders, J R; Sankar, S; Sannibale, V; Santiago-Prieto, I; Saracco, E; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Savage, R; Scheuer, J; Schilling, R; Schilman, M; Schmidt, P; Schnabel, R; Schofield, R M S; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Shaddock, D A; Shah, S; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Shoemaker, D H; Sidery, T L; Siellez, K; Siemens, X; Sigg, D; Simakov, D; Singer, A; Singer, L; Singh, R; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, R J E; Smith-Lefebvre, N D; Son, E J; Sorazu, B; Souradeep, T; Staley, A; Stebbins, J; Steinke, M; Steinlechner, J; Steinlechner, S; Stephens, B C; Steplewski, S; Stevenson, S; Stone, R; Stops, D; Strain, K A; Straniero, N; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Susmithan, S; Sutton, P J; Swinkels, B; Tacca, M; Talukder, D; Tanner, D B; Tao, J; Tarabrin, S P; Taylor, R; Tellez, G; Thirugnanasambandam, M P; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Travasso, F; Traylor, G; Tse, M; Tshilumba, D; Tuennermann, H; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Beuzekom, M; van den Brand, J F J; Van Den Broeck, C; van der Sluys, M V; van Heijningen, J; van Veggel, A A; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vincent-Finley, R; Vinet, J-Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Vousden, W D; Vyachanin, S P; Wade, A R; Wade, L; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, M; Wang, X; Ward, R L; Was, M; Weaver, B; Wei, L-W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; White, D J; Whiting, B F; Wiesner, K; Wilkinson, C; Williams, K; Williams, L; Williams, R; Williams, T D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Wolovick, N; Worden, J; Wu, Y; Yablon, J; Yakushin, I; Yam, W; Yamamoto, H; Yancey, C C; Yang, H; Yoshida, S; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J-P; Zhang, Fan; Zhang, L; Zhao, C; Zhu, H; Zhu, X J; Zucker, M E; Zuraw, S; Zweizig, J; Aptekar, R L; Atteia, J L; Cline, T; Connaughton, V; Frederiks, D D; Golenetskii, S V; Hurley, K; Krimm, H A; Marisaldi, M; Pal'shin, V D; Palmer, D; Svinkin, D S; Terada, Y; von Kienlin, A

    2014-07-01

    We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

  4. Search for Gravitational Waves Associated with γ-ray Bursts Detected by the Interplanetary Network

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Andersen, M.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Augustus, H.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauchrowitz, J.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Beker, M. G.; Belczynski, C.; Bell, A. S.; Bell, C.; Bergmann, G.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bosi, L.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burman, R.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castaldi, G.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Celerier, C.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Croce, R. P.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fazi, D.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Feroz, F.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Ha, J.; Hall, E. D.; Hamilton, W.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Holt, K.; Hopkins, P.; Horrom, T.; Hoske, D.; Hosken, D. J.; Hough, J.; Howell, E. J.

    2014-07-01

    We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10-2M⊙c2 at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

  5. Combined reconstruction of weak and strong lensing data with WSLAP

    NASA Astrophysics Data System (ADS)

    Diego, J. M.; Tegmark, M.; Protopapas, P.; Sandvik, H. B.

    2007-03-01

    We describe a method to estimate the mass distribution of a gravitational lens and the position of the sources from combined strong and weak lensing data. The algorithm combines weak and strong lensing data in a unified way producing a solution which is valid in both the weak and the strong lensing regimes. The method is non-parametric, allowing the mass to be located anywhere in the field of view. We study how the solution depends on the choice of basis used to represent the mass distribution. We find that combining weak and strong lensing information has two major advantages: it alleviates the need for priors and/or regularization schemes for the intrinsic size of the background galaxies (this assumption was needed in previous strong lensing algorithms) and it reduces (although does not remove) biases in the recovered mass in the outer regions where the strong lensing data are less sensitive. The code is implemented into a software package called Weak & Strong Lensing Analysis Package (WSLAP) which is publicly available at http://darwin.cfa.harvard.edu/SLAP/.

  6. Neutrino halos in clusters of galaxies and their weak lensing signature

    SciTech Connect

    Villaescusa-Navarro, Francisco; Peña-Garay, Carlos; Miralda-Escudé, Jordi; Quilis, Vicent E-mail: miralda@icc.ub.es E-mail: vicent.quilis@uv.es

    2011-06-01

    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.

  7. Atmospheric Dispersion Effects in Weak Lensing Measurements

    SciTech Connect

    Plazas, Andrés Alejandro; Bernstein, Gary

    2012-10-01

    The wavelength dependence of atmospheric refraction causes elongation of finite-bandwidth images along the elevation vector, which produces spurious signals in weak gravitational lensing shear measurements unless this atmospheric dispersion is calibrated and removed to high precision. Because astrometric solutions and PSF characteristics are typically calibrated from stellar images, differences between the reference stars' spectra and the galaxies' spectra will leave residual errors in both the astrometric positions (dr) and in the second moment (width) of the wavelength-averaged PSF (dv) for galaxies.We estimate the level of dv that will induce spurious weak lensing signals in PSF-corrected galaxy shapes that exceed the statistical errors of the DES and the LSST cosmic-shear experiments. We also estimate the dr signals that will produce unacceptable spurious distortions after stacking of exposures taken at different airmasses and hour angles. We also calculate the errors in the griz bands, and find that dispersion systematics, uncorrected, are up to 6 and 2 times larger in g and r bands,respectively, than the requirements for the DES error budget, but can be safely ignored in i and z bands. For the LSST requirements, the factors are about 30, 10, and 3 in g, r, and i bands,respectively. We find that a simple correction linear in galaxy color is accurate enough to reduce dispersion shear systematics to insignificant levels in the r band for DES and i band for LSST,but still as much as 5 times than the requirements for LSST r-band observations. More complex corrections will likely be able to reduce the systematic cosmic-shear errors below statistical errors for LSST r band. But g-band effects remain large enough that it seems likely that induced systematics will dominate the statistical errors of both surveys, and cosmic-shear measurements should rely on the redder bands.

  8. Atmospheric Dispersion Effects in Weak Lensing Measurements

    DOE PAGESBeta

    Plazas, Andrés Alejandro; Bernstein, Gary

    2012-10-01

    The wavelength dependence of atmospheric refraction causes elongation of finite-bandwidth images along the elevation vector, which produces spurious signals in weak gravitational lensing shear measurements unless this atmospheric dispersion is calibrated and removed to high precision. Because astrometric solutions and PSF characteristics are typically calibrated from stellar images, differences between the reference stars' spectra and the galaxies' spectra will leave residual errors in both the astrometric positions (dr) and in the second moment (width) of the wavelength-averaged PSF (dv) for galaxies.We estimate the level of dv that will induce spurious weak lensing signals in PSF-corrected galaxy shapes that exceed themore » statistical errors of the DES and the LSST cosmic-shear experiments. We also estimate the dr signals that will produce unacceptable spurious distortions after stacking of exposures taken at different airmasses and hour angles. We also calculate the errors in the griz bands, and find that dispersion systematics, uncorrected, are up to 6 and 2 times larger in g and r bands,respectively, than the requirements for the DES error budget, but can be safely ignored in i and z bands. For the LSST requirements, the factors are about 30, 10, and 3 in g, r, and i bands,respectively. We find that a simple correction linear in galaxy color is accurate enough to reduce dispersion shear systematics to insignificant levels in the r band for DES and i band for LSST,but still as much as 5 times than the requirements for LSST r-band observations. More complex corrections will likely be able to reduce the systematic cosmic-shear errors below statistical errors for LSST r band. But g-band effects remain large enough that it seems likely that induced systematics will dominate the statistical errors of both surveys, and cosmic-shear measurements should rely on the redder bands.« less

  9. Studies of gravitational lens systems discovered in the Cosmic Lens All-Sky Survey

    NASA Astrophysics Data System (ADS)

    Rusin, David Joseph

    2001-11-01

    This thesis describes research conducted on and inspired by the Cosmic Lens All-Sky Survey (CLASS), which searches for new cases of gravitational lensing among compact radio sources. CLASS aims to provide the largest and best-studied sample of lens systems for use in constraining the properties of galaxy mass distributions, determining the Hubble parameter and placing limits on the cosmological constant. The goal of this thesis was to complete observations of the CLASS sample, discover and thoroughly investigate new lenses, and apply them to interesting astrophysical problems. We begin with a detailed overview of the CLASS project, including scientific goals, the radio source sample, survey observations, candidate selection and follow-ups. Results are then presented from the third phase of the CLASS survey (CLASS-3), which yielded three new gravitational lens systems. 130850+054 and 131152+199 both consist of a pair of lensed images. 131359+154 features six images of a single source, and is the first arcsecond-scale system in which a source is lensed into more than four images. We also present observations and modeling of the CLASS-2 gravitational lens B2319+051. We use the absence of detectable central images in deep radio maps of CLASS lens systems to place powerful constraints on the inner mass profiles of leasing galaxies. These analyses imply that the profile slopes cannot be much shallower than isothermal. Finally, we consider the relative frequency of two and four-image lens systems, and demonstrate that there is a statistically significant overdensity of quads in the CLASS sample. We investigate a range of factors that may be increasing the frequency of radio quads, including external shear fields, mass distributions flatter than the light, shallow leasing mass profiles, finite core radii, satellite galaxies, and alterations to the luminosity function for faint flat-spectrum radio sources. Surprisingly, none of these mechanisms provide a particularly

  10. A New Physical Model for Pulsars as Gravitational Shielding and Oscillating Neutron Stars

    NASA Astrophysics Data System (ADS)

    Zhang, Tianxi

    2014-06-01

    Pulsars are fast rotating neutron stars that synchronously emit periodic Dirac delta shape pulses of radio-frequency radiation and Lorentzian shape oscillations of X-rays. The acceleration of particles near the magnetic poles, which derivate from the rotating axis produces coherent beams of radio emissions that are viewed as pulses of radiation whenever the magnetic poles sweep the viewers. However, the conventional lighthouse model of pulsars is only conceptual. The physical mechanism through which particles are accelerated to produce coherent beams of radio emissions is still poorly understood. The process for periodically oscillating X-rays to emit from hot spots at the inner edge of accretion disks of pulsars is also remained as an unsolved mystery. Recently, a new physical model of pulsars is proposed by the author to quantitatively interpret the emission characteristics of pulsars, in accordance with his well-developed five-dimensional fully covariant Kaluza-Klein gravitational shielding theory and the physics of thermal and accelerating charged particle radiation. The results indicate that with the significant gravitational shielding by scalar field a neutron star nonlinearly oscillates and produces synchronous periodically Dirac delta shape pulse-like radio-frequency radiation (emitted by the oscillating or accelerating charged particles) as well as periodically Lorentzian shape oscillating X-rays (as the thermal radiation of neutron stars that temperature varies due to the oscillation). This physical model of pulsars as gravitational shielding and oscillating neutron stars broadens our understanding of neutron stars and develops an innovative mechanism to disclose the mystery of pulsars. In this presentation, I will show the results obtained from the quantitative studies of this new physical model of pulsars for the oscillations of neutron stars and the powers of radio pulse-like emissions and oscillating X-rays.

  11. Constructing black hole entropy from gravitational collapse

    NASA Astrophysics Data System (ADS)

    Acquaviva, Giovanni; Ellis, George F. R.; Goswami, Rituparno; Hamid, Aymen I. M.

    2015-03-01

    Based on a recent proposal for the gravitational entropy of free gravitational fields, we investigate the thermodynamic properties of black hole formation through gravitational collapse in the framework of the semitetrad 1 +1 +2 covariant formalism. In the simplest case of an Oppenheimer-Snyder-Datt collapse, we prove that the change in gravitational entropy outside a collapsing body is related to the variation of the surface area of the body itself, even before the formation of horizons. As a result, we are able to relate the Bekenstein-Hawking entropy of the black hole end state to the variation of the vacuum gravitational entropy outside the collapsing body.

  12. Gravitational Waves in Effective Quantum Gravity

    NASA Astrophysics Data System (ADS)

    Calmet, Xavier; Kuntz, Iberê; Mohapatra, Sonali

    2016-08-01

    In this short paper we investigate quantum gravitational effects on Einstein's equations using Effective Field Theory techniques. We consider the leading order quantum gravitational correction to the wave equation. Besides the usual massless mode, we find a pair of modes with complex masses. These massive particles have a width and could thus lead to a damping of gravitational waves if excited in violent astrophysical processes producing gravitational waves such as e.g. black hole mergers. We discuss the consequences for gravitational wave events such as GW 150914 recently observed by the Advanced LIGO collaboration.

  13. Gravitational Wave Astrophysics: Opening the New Frontier

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2011-01-01

    The gravitational wave window onto the universe is expected to open in approx. 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters, through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum.

  14. Gravitational Wave Astrophysics: Opening the New Frontier

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2011-01-01

    The gravitational wave window onto the universe is expected to open in approximately 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum.

  15. Gravitational collapse in f(R) theories

    SciTech Connect

    Cembranos, J.A.R.; Cruz-Dombriz, A. de la; Núñez, B. Montes E-mail: alvaro.delacruzdombriz@uct.ac.za

    2012-04-01

    We study the gravitational collapse in modified gravitational theories. In particular, we analyze a general f(R) model with uniformly collapsing cloud of self-gravitating dust particles. This analysis shares analogies with the formation of large-scale structures in the early Universe and with the formation of stars in a molecular cloud experiencing gravitational collapse. In the same way, this investigation can be used as a first approximation to the modification that stellar objects can suffer in these modified theories of gravity. We study concrete examples, and find that the analysis of gravitational collapse is an important tool to constrain models that present late-time cosmological acceleration.

  16. Gravitational Cooling of Self-gravitating Bose Condensates

    NASA Astrophysics Data System (ADS)

    Guzmán, F. Siddhartha; Ureña-López, L. Arturo

    2006-07-01

    Equilibrium configurations for a self-gravitating scalar field with self-interaction are constructed. The corresponding Schrödinger-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 their 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 pointlike.

  17. Determining gravitational radiation from Newtonian self-gravitating systems

    NASA Astrophysics Data System (ADS)

    Finn, Lee Samuel; Evans, Charles R.

    1990-03-01

    Quadrupole gravitational radiation formulas are tested and compared in a calculation of rotating stellar core collapse. While the standard quadrupole formula (SQF) allows an economical calculation of the waveform in postlinear gravity, it has several shortcomings that become apparent in a finite difference (FD) calculation. These shortcomings are related to the large-moment arm of the quadrupole moment and the two (numerical) time derivatives that separate it from the waveform. These shortcomings lead to high-frequency noise in the SQF waveform. Several alternatives to the SQF are developed. Each is mathematically equivalent to the SQF and applicable to self-gravitating sources. For FD calculations, the new quadrupole formulas are all superior to the SQF and capable of producing waveforms free of the high-frequency noise characteristics of its use.

  18. Capabilities and Limitations of Radio Occultation Measurements for Ionosphere Monitoring

    NASA Technical Reports Server (NTRS)

    Hajj, G. A.; Romans, L. J.; Pi, X.; Wang, Chunming

    1999-01-01

    The paper: (1) describes the range of capabilities of GPS radio occultation missions in ionospheric research: (a) ionospheric profiling; (b) ionospheric imaging; (c) ionospheric data assimilation; and (d) measurement of scintillation. (2) Identify strengths and weaknesses of measurements: (a) coverage; (b) resolution; and (c) uniqueness of solution.

  19. Radio broadcasting via satellite

    NASA Astrophysics Data System (ADS)

    Helm, Neil R.; Pritchard, Wilbur L.

    1990-10-01

    Market areas offering potential for future narrowband broadcast satellites are examined, including international public diplomacy, government- and advertising-supported, and business-application usages. Technical issues such as frequency allocation, spacecraft types, transmission parameters, and radio receiver characteristics are outlined. Service and system requirements, advertising revenue, and business communications services are among the economic issues discussed. The institutional framework required to provide an operational radio broadcast service is studied, and new initiatives in direct broadcast audio radio systems, encompassing studies, tests, in-orbit demonstrations of, and proposals for national and international commercial broadcast services are considered.

  20. Spherical gravitational curvature boundary-value problem

    NASA Astrophysics Data System (ADS)

    Šprlák, Michal; Novák, Pavel

    2016-08-01

    Values of scalar, vector and second-order tensor parameters of the Earth's gravitational field have been collected by various sensors in geodesy and geophysics. Such observables have been widely exploited in different parametrization methods for the gravitational field modelling. Moreover, theoretical aspects of these quantities have extensively been studied and well understood. On the other hand, new sensors for observing gravitational curvatures, i.e., components of the third-order gravitational tensor, are currently under development. As the gravitational curvatures represent new types of observables, their exploitation for modelling of the Earth's gravitational field is a subject of this study. Firstly, the gravitational curvature tensor is decomposed into six parts which are expanded in terms of third-order tensor spherical harmonics. Secondly, gravitational curvature boundary-value problems defined for four combinations of the gravitational curvatures are formulated and solved in spectral and spatial domains. Thirdly, properties of the corresponding sub-integral kernels are investigated. The presented mathematical formulations reveal some important properties of the gravitational curvatures and extend the so-called Meissl scheme, i.e., an important theoretical framework that relates various parameters of the Earth's gravitational field.