Scalar Stochastic Gravitational-Wave Background in Brans-Dicke Theory of Gravity

Abstract

We study the scalar stochastic gravitational-wave background (SGWB) from astrophysical sources, including compact binary mergers and stellar collapses, in the Bras-Dicke theory of gravity. By contrast to tensor waves, we found the scalar SGWB to predominantly arise from stellar collapses. These collapses not only take place at higher astrophysical rates, but emit more energy. This is because, unlike tensor radiation, which mainly starts from quadrupole order, the scalar perturbation can be excited by changes in the monopole moment. In particular, in the case of stellar collapse into a neutron star or a black hole, the monopole radiation, at frequencies below 100\,Hz, is dominated by the memory effect. At low frequencies, the scalar SGWB spectrum follows a power law of ${\Omega }_{\text{S}}\propto f^{\alpha }$, with $\alpha =1$. We predict that ${\Omega }_{\text{S}}$ is inversely proportional to the square of ${\omega }_{\mathrm{BD}}+2$, with $({\omega }_{\mathrm{BD}}+2{)}^2{\Omega }_S(f=25\mathrm{Hz})=2.8\times 10^{-6}$. We also estimate the detectability of the scalar SGWB for current and third-generation detector networks, and the bound on ${\omega }_{\mathrm{BD}}$ that can be imposed from these observations.

9 pages, 8 figures

References in corpus (8)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence
• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
• Probing non-tensorial polarizations of stochastic gravitational-wave backgrounds with ground-based laser interferometers
• The Impact of Star Formation and Gamma-Ray Burst Rates at High Redshift on Cosmic Chemical Evolution and Reionization
• Gravitational Wave Memory: A New Approach to Study Modified Gravity
• Observational upper limits on the gravitational wave production of core collapse supernovae

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• Propagation and emission of gravitational waves in the weak-field limit within the Palatini formalism