scholarly journals Scalar gravitational wave from Oppenheimer-Snyder collapse in scalar-tensor theories of gravity

1997 ◽  
Vol 55 (4) ◽  
pp. 2024-2037 ◽  
Author(s):  
Tomohiro Harada ◽  
Takeshi Chiba ◽  
Ken-ichi Nakao ◽  
Takashi Nakamura
Keyword(s):  
Gravitational Wave ◽  
Theories Of Gravity

scholarly journals Constraining Modified Theories of Gravity with Gravitational-Wave Stochastic Backgrounds

2016 ◽  
Vol 117 (9) ◽  
Author(s):  
Andrea Maselli ◽  
Stefania Marassi ◽  
Valeria Ferrari ◽  
Kostas Kokkotas ◽  
Raffaella Schneider
Keyword(s):  
Gravitational Wave ◽  
Modified Theories Of Gravity ◽  
Theories Of Gravity ◽  
Stochastic Backgrounds

scholarly journals Improved gravitational-wave constraints on higher-order curvature theories of gravity

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
Scott E. Perkins ◽  
Remya Nair ◽  
Hector O. Silva ◽  
Nicolás Yunes
Keyword(s):  
Gravitational Wave ◽  
Higher Order ◽  
Theories Of Gravity

scholarly journals Constraints on alternative theories of gravity with observations of the Galactic Center

2018 ◽  
Vol 191 ◽  
pp. 01010 ◽  
Author(s):  
Alexander Zakharov
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Galactic Center ◽  
Alternative Theories Of Gravity ◽  
Significant Activity ◽  
Graviton Mass ◽  
The Future ◽  
Theories Of Gravity ◽  
Theory Of Gravity ◽  
Alternative Theories

To evaluate a potential usually one analyzes trajectories of test particles. For the Galactic Center case astronomers use bright stars or photons, so there are two basic observational techniques to investigate a gravitational potential, namely, (a) monitoring the orbits of bright stars near the Galactic Center as it is going on with 10m Keck twin and four 8m VLT telescopes equipped with adaptive optics facilities (in addition, recently the IR interferometer GRAVITY started to operate with VLT); (b) measuring the size and shape of shadows around black hole with VLBI-technique using telescopes operating in mm-band. At the moment, one can use a small relativistic correction approach for stellar orbit analysis, however, in the future the approximation will not be precise enough due to enormous progress of observational facilities and recently the GRAVITY team found that the first post-Newtonian correction has to be taken into account for the gravitational redshift in the S2 star orbit case. Meanwhile for smallest structure analysis in VLBI observations one really needs a strong gravitational field approximation. We discuss results of observations and their interpretations. In spite of great efforts there is a very slow progress to resolve dark matter (DM) and dark energy (DE) puzzles and in these circumstances in last years a number of alternative theories of gravity have been proposed. Parameters of these theories could be effectively constrained with of observations of the Galactic Center. We show some cases of alternative theories of gravity where their parameters are constrained with observations, in particular, we consider massive theory of gravity. We choose the alternative theory of gravity since there is a significant activity in this field and in the last years theorists demonstrated an opportunity to create such theories without ghosts, on the other hand, recently, the joint LIGO & Virgo team presented an upper limit on graviton mass such as mg< 1:2 × 10-22eV [1] analyzing gravitational wave signal in their first paper where they reported about the discovery of gravitational waves from binary black holes as it was suggested by C. Will [2]. So, the authors concluded that their observational data do not indicate a significant deviation from classical general relativity. We show that an analysis of bright star trajectories could estimate a graviton mass with a commensurable accuracy in comparison with an approach used in gravitational wave observations and the estimates obtained with these two approaches are consistent. Therefore, such an analysis gives an opportunity to treat observations of bright stars near the Galactic Center as a useful tool to obtain constraints on the fundamental gravity law. We showed that in the future graviton mass estimates obtained with analysis of trajectories of bright stars would be better than current LIGO bounds on the value, therefore, based on a potential reconstruction at the Galactic Center we obtain bounds on a graviton mass and these bounds are comparable with LIGO constraints. Analyzing size of shadows around the supermassive black hole at the Galactic Center (or/and in the center of M87) one could constrain parameters of different alternative theories of gravity as well.

scholarly journals Probing the theory of gravity with gravitational lensing of gravitational waves and galaxy surveys

2020 ◽  
Vol 494 (2) ◽  
pp. 1956-1970 ◽  
Author(s):  
Suvodip Mukherjee ◽  
Benjamin D Wandelt ◽  
Joseph Silk
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gravitational Lensing ◽  
Cross Correlation ◽  
Laser Interferometer ◽  
Galaxy Surveys ◽  
Einstein Telescope ◽  
Laser Interferometer Space Antenna ◽  
Theories Of Gravity ◽  
Theory Of Gravity

ABSTRACT The cross-correlation of gravitational wave strain with upcoming galaxy surveys probes theories of gravity in a new way. This method enables testing the theory of gravity by combining the effects from both gravitational lensing of gravitational waves and the propagation of gravitational waves in space–time. We find that within 10 yr the combination of the Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) and VIRGO (Virgo interferometer) detector networks with planned galaxy surveys should detect weak gravitational lensing of gravitational waves in the low-redshift Universe (z &lt; 0.5). With the next-generation gravitational wave experiments such as Voyager, LISA (Laser Interferometer Space Antenna), Cosmic Explorer, and the Einstein Telescope, we can extend this test of the theory of gravity to larger redshifts by exploiting the synergies between electromagnetic wave and gravitational wave probes.

scholarly journals The NANOGrav 12.5-year Data Set: Search for Non-Einsteinian Polarization Modes in the Gravitational-wave Background

2021 ◽  
Vol 923 (2) ◽  
pp. L22
Author(s):  
Zaven Arzoumanian ◽  
Paul T. Baker ◽  
Harsha Blumer ◽  
Bence Bécsy ◽  
Adam Brazier ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Signal To Noise Ratio ◽  
Simulated Data ◽  
Reference Frequency ◽  
Spatial Correlations ◽  
Signal To Noise ◽  
Data Set ◽  
Upper Limits ◽  
Theories Of Gravity ◽  
Gravitational Wave Background

Abstract We search NANOGrav’s 12.5 yr data set for evidence of a gravitational-wave background (GWB) with all the spatial correlations allowed by general metric theories of gravity. We find no substantial evidence in favor of the existence of such correlations in our data. We find that scalar-transverse (ST) correlations yield signal-to-noise ratios and Bayes factors that are higher than quadrupolar (tensor-transverse, TT) correlations. Specifically, we find ST correlations with a signal-to-noise ratio of 2.8 that are preferred over TT correlations (Hellings and Downs correlations) with Bayesian odds of about 20:1. However, the significance of ST correlations is reduced dramatically when we include modeling of the solar system ephemeris systematics and/or remove pulsar J0030+0451 entirely from consideration. Even taking the nominal signal-to-noise ratios at face value, analyses of simulated data sets show that such values are not extremely unlikely to be observed in cases where only the usual TT modes are present in the GWB. In the absence of a detection of any polarization mode of gravity, we place upper limits on their amplitudes for a spectral index of γ = 5 and a reference frequency of f yr = 1 yr−1. Among the upper limits for eight general families of metric theories of gravity, we find the values of A TT 95 % = ( 9.7 ± 0.4 ) × 10 − 16 and A ST 95 % = ( 1.4 ± 0.03 ) × 10 − 15 for the family of metric spacetime theories that contain both TT and ST modes.

scholarly journals The future of gravitational theories in the era of the gravitational wave astronomy

2018 ◽  
Vol 27 (05) ◽  
pp. 1850060 ◽  
Author(s):  
Christian Corda
Keyword(s):  
Gravitational Wave ◽  
Response Function ◽  
Massive Mode ◽  
Gravitational Theories ◽  
Massless Mode ◽  
The Future ◽  
Theories Of Gravity ◽  
Theoretical Results

We discuss the future of gravitational theories in the framework of gravitational wave (GW) astronomy after the recent GW detections (the events GW150914, GW151226, GW170104, GW170814, GW170817 and GW170608). In particular, a calculation of the frequency and angular dependent response function that a GW detector would see if massive modes from [Formula: see text] theories or scalar–tensor gravity (STG) were present, allowing for sources incident from any direction on the sky, is shown. In addition, through separate theoretical results which do not involve the recent GW detections, we show that [Formula: see text] theories of gravity having a third massless mode are ultimately ruled out while there is still room for STG having a third (massive or massless) mode and for [Formula: see text] theories of gravity having a third massive mode.

scholarly journals TESTS OF GENERAL RELATIVITY AND ALTERNATIVE THEORIES OF GRAVITY USING GRAVITATIONAL WAVE OBSERVATIONS

2013 ◽  
Vol 22 (01) ◽  
pp. 1341012 ◽  
Author(s):  
K. G. ARUN ◽  
ARCHANA PAI
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Strong Field ◽  
Information Matrix ◽  
Simons Theory ◽  
Alternative Theories Of Gravity ◽  
Newtonian Theory ◽  
Theories Of Gravity ◽  
Model Independent ◽  
Alternative Theories

Gravitational wave (GW) observations of coalescing compact binaries will be unique probes of strong-field, dynamical aspects of relativistic gravity. We present a short review of various schemes proposed in the literature to test general relativity (GR) and alternative theories of gravity using inspiral waveforms. Broadly these schemes may be classified into two types: model dependent and model independent. In the model dependent category, GW observations are compared against a specific waveform model representative of a particular theory or a class of theories such as scalar-tensor theories, dynamical Chern–Simons theory and massive graviton theories. Model independent tests are attempts to write down a parametrized gravitational waveform where the free parameters take different values for different theories and (at least some of) which can be constrained by GW observations. We revisit some of the proposed bounds in the case of downscaled LISA configuration (eLISA) and compare them with the original LISA configuration. We also compare the expected bounds on alternative theories of gravity from ground-based and space-based detectors and find that space-based GW detectors can test GR and other theories of gravity with unprecedented accuracies. We then focus on a recent proposal to use singular value decomposition of the Fisher information matrix to improve the accuracies with which post-Newtonian theory can be tested. We extend those results to the case of space-based detector eLISA and discuss its implications.

scholarly journals Gravitational Wave Polarizations in f (R) Gravity and Scalar-Tensor Theory

2018 ◽  
Vol 168 ◽  
pp. 01003 ◽  
Author(s):  
Yungui Gong ◽  
Shaoqi Hou
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Alternative Theories Of Gravity ◽  
Longitudinal Polarization ◽  
New Era ◽  
Tensor Theory ◽  
Pulsar Timing ◽  
Theories Of Gravity ◽  
Pulsar Timing Array ◽  
Scalar Mode

The detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory opens a new era to use gravitational waves to test alternative theories of gravity. We investigate the polarizations of gravitational waves in f (R) gravity and Horndeski theory, both containing scalar modes. These theories predict that in addition to the familiar + and × polarizations, there are transverse breathing and longitudinal polarizations excited by the massive scalar mode and the new polarization is a single mixed state. It would be very difficult to detect the longitudinal polarization by interferometers, while pulsar timing array may be the better tool to detect the longitudinal polarization.

scholarly journals Gravitational-wave cosmological distances in scalar-tensor theories of gravity

2021 ◽  
Vol 2021 (06) ◽  
pp. 050
Author(s):  
Gianmassimo Tasinato ◽  
Alice Garoffolo ◽  
Daniele Bertacca ◽  
Sabino Matarrese
Keyword(s):  
Gravitational Wave ◽  
Theories Of Gravity
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