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General Relativity and Quantum Cosmology, gr-qc
Abstract:
We perform tests of General Relativity (GR) with gravitational waves (GWs)
from the inspiral stage of compact binaries using a theory-independent
framework, which adds generic phase corrections to each multipole of a GR
waveform model in frequency domain. This method has been demonstrated on
LIGO-Virgo observations to provide stringent constraints on post-Newtonian
predictions of the inspiral and to assess systematic biases that may arise in
such parameterized tests. Here, we detail the anatomy of our framework for
aligned-spin waveform models. We explore the effects of higher modes in the
underlying signal on tests of GR through analyses of two unequal-mass,
simulated binary signals similar to GW190412 and GW190814. We show that the
inclusion of higher modes improves both the precision and the accuracy of the
measurement of the deviation parameters. Our testing framework also allows us
to vary the underlying baseline GR waveform model and the frequency at which
the non-GR inspiral corrections are tapered off. We find that to optimize the
GR test of high-mass binaries, comprehensive studies would need to be done to
determine the best choice of the tapering frequency as a function of the
binary's properties. We also carry out an analysis on the binary neutron-star
event GW170817 to set bounds on the coupling constant $\alpha_0$ of
Jordan-Fierz-Brans-Dicke gravity. We take two plausible approaches; in the
first \emph{theory-agnostic} approach we find a bound $\alpha_0 \lesssim
2\times 10^{-1}$ from measuring the dipole-radiation for different neutron-star
equations of state, while in the second \emph{theory-specific} approach we
obtain $\alpha_0 \lesssim 4\times 10^{-1}$, both at $68\%$ credible level.
These differences arise mainly due to different statistical hypotheses used for
the analysis.
