Gravitational memory effects in <scp>Brans‐Dicke</scp> theory

Hou, S.

doi:10.1002/asna.202113887

Cited by 11 publications

(9 citation statements)

References 41 publications

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“…Therefore, with these gravitational wave detectors, one can observe memory effects of the tensor modes, i.e., displacement, spin and CM memories. These tensor memory effects are very similar to those predicted in general relativity [12-14, 27, 43, 59] and Brans-Dicke theory [48,55,56,60,61]. In particular, they are constrained by the evolution equations (2.5g) and (2.5h).…”

Section: Chern-simons Modified Gravitysupporting

confidence: 81%

Conserved charges in Chern-Simons modified theory and memory effects

Hou,

Zhu,

Zhu

2021

Preprint

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In this work, conserved charges and fluxes at the future null infinity are determined in the asymptotically flat spacetime for Chern-Simons modified gravity. The flux-balance laws are used to constrain the memory effects. For tensor memories, the Penrose's conformal completion method is used to analyze the asymptotic structures and asymptotic symmetries, and then, conserved charges for the Bondi-Metzner-Sachs algebra are constructed with the Wald-Zoupas formalism. These charges take very similar forms to those in Brans-Dicke theory. For the scalar memory, Chern-Simons modified gravity is rewritten in the first-order formalism, and the scalar field is replaced by a 2-form field dual to it. With this dual formalism, the scalar memory is described by the vacuum transition induced by the large gauge transformation of the 2-form field.

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Section: Chern-simons Modified Gravitysupporting

confidence: 81%

Conserved charges in Chern-Simons modified theory and memory effects

Hou,

Zhu,

Zhu

2021

Preprint

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“…This is just the geodesic deviation equation, and used to detect gravitational waves by interferometers [59]. Applying this equation to the test particles near the null infinity of the spacetime considered in the previous section, one obtains the following relative acceleration [60],…”

Section: Geodesic Deviationmentioning

confidence: 99%

“…From the above discussion, one knows that memory effects are related to ∆c AB and C AB . These two quantities are constrained by conservation laws associated with the extended BMS symmetries [37,38,48,60]. This requires to determine the conserved charges and the fluxes using certain formalisms such as the one in ref.…”

Section: Constraints On Memory Effectsmentioning

confidence: 99%

“…To summarize, here, one properly integrates the evolution equations (3.12b) and (3.12c) multiplied by generators of the extended BMS transformations, then the constraints on various memory effects are obtained. Usually, these constraints are expressed as fluxes and the changes in the conserved charges associated with the extended BMS symmetry [37,38,60,72]. So in principle, one can identify those charges and fluxes in the above constraint equations.…”

Section: Constraints On Memory Effectsmentioning

confidence: 99%

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Gravitational memory effects in Chern-Simons modified gravity

Hou,

Zhu,

Zhu

2021

Preprint

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The gravitational memory effects of Chern-Simons modified gravity are considered in the asymptotically flat spacetime. If the Chern-Simons scalar does not directly couple with the ordinary matter fields, there are also displacement, spin and center-of-mass memory effects as in general relativity. This is because the term of the action that violates the parity invariance is linear in the scalar field but quadratic in the curvature tensor. This results in the parity violation occuring at the higher orders in the inverse luminosity radius. Although there exists the Chern-Simons scalar field, interferometers and pulsar timing arrays are incapable of detecting its polarization. So the scalar field does not induce any new memory effects that can be detected by interferometers or pulsar timing arrays. The asymptotic symmetry is group is also the extended Bondi-Metzner-Sachs group. The constraints on the memory effects excited by the tensor modes are obtained.

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“…In particular, the memory strain from compact binary objects has been expected to be only one order of magnitude weaker than the standard GW strain [23,31]. As a test of gravity theories, the memory effect has been studied as a result of massive gravity [40], scalar-tensor theories [41][42][43], as well as in the strong-field regime [44]. In addition, novel phenomena, different from the conventional displacement memory effect, have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Leading-order nonlinear gravitational waves from reheating magnetogeneses

He,

Pol,

Brandenburg

2021

Preprint

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We study the leading-order nonlinear gravitational waves (GWs) produced by an electromagnetic (EM) stress in reheating magnetogenesis scenarios. Both nonhelical and helical magnetic fields are considered. By numerically solving the linear and leading-order nonlinear GW equations, we find that the GW energy from the latter is usually larger. We compare their differences in terms of the GW spectrum and parameterize the GW energy difference due to the nonlinear term, ∆EGW, in terms of EM energy EEM as ∆EGW = (pEEM/k * ) 3 , where k * is the characteristic wave number, p = 0.84 and 0.88 are found in the nonhelical and helical cases, respectively, with reheating around the QCD energy scale, while p = 0.45 is found at the electroweak energy scale. We also compare the polarization spectrum of the linear and nonlinear cases and find that adding the nonlinear term usually yields a decrease in the polarization that is proportional to the EM energy density. We parameterize the fractional polarization suppression as |∆PGW/PGW| = rEEM/k * and find r = 1.2 × 10 −1 , 7.2 × 10 −4 , and 3.2 × 10 −2 for the helical cases with reheating temperatures Tr = 300 TeV, 8 GeV, and 120 MeV, respectively. Prospects of observation by pulsar timing arrays, space-based interferometers, and other novel detection proposals are also discussed.

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Gravitational memory effects in Brans‐Dicke theory

Cited by 11 publications

References 41 publications

Conserved charges in Chern-Simons modified theory and memory effects

Conserved charges in Chern-Simons modified theory and memory effects

Gravitational memory effects in Chern-Simons modified gravity

Leading-order nonlinear gravitational waves from reheating magnetogeneses

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