scholarly journals Inverse-chirp imprint of gravitational wave signals in scalar tensor theory

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Chao-Qiang Geng ◽  
Hao-Jui Kuan ◽  
Ling-Wei Luo
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Parameter Space ◽  
Coupling Function ◽  
Transformation Rule ◽  
Core Collapse ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Jordan And Einstein Frames

Abstract The scalar tensor theory contains a coupling function connecting the quantities in the Jordan and Einstein frames, which is constrained to guarantee a transformation rule between frames. We simulate the supernovae core collapse with different choices of coupling functions defined over the viable region of the parameter space and find that a generic inverse-chirp feature of the gravitational waves in the scalar tensor scenario.

scholarly journals EXACT SOLUTIONS FOR COSMOLOGICAL MODELS WITH A SCALAR FIELD

2002 ◽  
Vol 17 (03) ◽  
pp. 375-381 ◽  
Author(s):  
H. MOTAVALI ◽  
M. GOLSHANI
Keyword(s):  
Scalar Field ◽  
Exact Solutions ◽  
Cosmological Models ◽  
Coupling Function ◽  
Noether Symmetry ◽  
Scalar Tensor Theory ◽  
Frw Cosmology ◽  
Field Equations ◽  
Tensor Theory ◽  
Cosmological Solutions

We consider the existence of a Noether symmetry in the scalar–tensor theory of gravity in flat Friedman–Robertson–Walker (FRW) cosmology. The forms of coupling function ω(ϕ) and generic potential V(ϕ) are obtained by requiring the existence of a Noether symmetry for such theory. We derive exact cosmological solutions of the field equations from a point-like Lagrangian.

scholarly journals Formation and Clustering of Primordial Black Holes in Brans-Dicke Theory

Universe ◽  
2020 ◽  
Vol 6 (10) ◽  
pp. 158
Author(s):  
Victor Berezin ◽  
Vyacheslav Dokuchaev ◽  
Yury Eroshenko ◽  
Alexey Smirnov
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Gravitational Wave ◽  
Significant Contribution ◽  
Threshold Value ◽  
Primordial Black Holes ◽  
Cosmological Horizon ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Density Perturbations

The formation of primordial black holes in the early universe in the Brans-Dicke scalar-tensor theory of gravity is investigated. Corrections to the threshold value of density perturbations are found. Above the threshold, the gravitational collapse occurs after the cosmological horizon crossing. The corrections depend in a certain way on the evolving scalar field. They affect the probability of primordial black holes formation, and can lead to their clustering at large scales if the scalar field is inhomogeneous. The formation of the clusters, in turn, increases the probability of black holes merge and the corresponding rate of gravitational wave bursts. The clusters can provide a significant contribution to the LIGO/Virgo gravitational wave events, if part of the observed events are associated with primordial black holes.

Scalar-Tensor Theory and Gravitational Waves

1970 ◽  
Vol 1 (12) ◽  
pp. 3209-3216 ◽  
Author(s):  
Robert V. Wagoner
Keyword(s):  
Gravitational Waves ◽  
Scalar Tensor Theory ◽  
Tensor Theory

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 SEARCH FOR GRAVITATIONAL WAVES FROM SUPERNOVAE AND LONG GRBS

2013 ◽  
Vol 53 (A) ◽  
pp. 736-741 ◽  
Author(s):  
Maurice H.P.M. Van Putten
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Strong Interaction ◽  
Light Curves ◽  
Matched Filtering ◽  
Core Collapse ◽  
Local Universe ◽  
Wave Emission ◽  
Density Matter

We report on evidence for black hole spindown in the light curves of the BATSE catalogue of 1491 long GRBs by application of matched filtering. This observation points to a strong interaction of the black hole with surrounding high density matter at the ISCO, inducing non-axisymmetric instabilities sustained by cooling in gravitational wave emission. Opportunities for LIGO-Virgo and the recently funded KAGRA experiments are highlighted, for long GRBs with and without supernovae and for hyper-energetic core-collapse supernovae within a distance of about 35Mpc in the Local Universe.

scholarly journals SCALAR-TENSOR COSMOLOGIES: GENERAL RELATIVITY AS A FIXED POINT OF THE JORDAN FRAME SCALAR FIELD

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1631-1638 ◽  
Author(s):  
PIRET KUUSK ◽  
LAUR JÄRV ◽  
MARGUS SAAL
Keyword(s):  
General Relativity ◽  
Fixed Point ◽  
Scalar Field ◽  
Fixed Points ◽  
Coupling Function ◽  
Jordan Frame ◽  
Mathematical Form ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
General Scalar

We study the evolution of homogeneous and isotropic, flat cosmological models within the general scalar-tensor theory of gravity with arbitrary coupling function and potential and scrutinize its limit to general relativity. Using the methods of dynamical systems for the decoupled equation of the Jordan frame scalar field we find the fixed points of flows in two cases: potential domination and matter domination. We present the conditions on the mathematical form of the coupling function and potential which determine the nature of the fixed points (attractor or other). There are two types of fixed points, both are characterized by cosmological evolution mimicking general relativity, but only one of the types is compatible with the Solar System PPN constraints.

scholarly journals Constraining the gravitational-wave afterglow from a binary neutron star coalescence

2020 ◽  
Vol 492 (4) ◽  
pp. 4945-4951 ◽  
Author(s):  
Sharan Banagiri ◽  
Michael W Coughlin ◽  
James Clark ◽  
Paul D Lasky ◽  
M A Bizouard ◽  
...  
Keyword(s):  
Parameter Estimation ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Parameter Space ◽  
Spectral Content ◽  
Binary Neutron Star ◽  
Upper Limit ◽  
Long Duration ◽  
Likelihood Model

ABSTRACT Binary neutron star mergers are rich laboratories for physics, accessible with ground-based interferometric gravitational-wave detectors such as the Advanced LIGO and Advanced Virgo. If a neutron star remnant survives the merger, it can emit gravitational waves that might be detectable with the current or next generation detectors. The physics of the long-lived post-merger phase is not well understood and makes modelling difficult. In particular the phase of the gravitational-wave signal is not well modelled. In this paper, we explore methods for using long duration post-merger gravitational-wave signals to constrain the parameters and the properties of the remnant. We develop a phase-agnostic likelihood model that uses only the spectral content for parameter estimation and demonstrate the calculation of a Bayesian upper limit in the absence of a signal. With the millisecond magnetar model, we show that for an event like GW170817, the ellipticity of a long-lived remnant can be constrained to less than about 0.5 in the parameter space used.

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