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General Relativity and Quantum Cosmology, gr-qc, Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
We perform several consistency tests between different phases of binary black
hole dynamics; the inspiral, the merger, and the ringdown on the gravitational
wave events GW150914 and GW170814. These tests are performed explicitly in the
time domain, without any spectral leakage between the different phases. We
compute posterior distributions on the mass and spin of the initial black holes
and the final black hole. We also compute the initial areas of the two
individual black holes and the final area from the parameters describing the
remnant black hole. This facilitates a test of Hawking's black hole area
theorem. We use different waveform models to quantify systematic waveform
uncertainties for the area increase law with the two events. We find that these
errors may lead to overstating the confidence with which the area theorem is
confirmed. For example, we find $>99\%$ agreement with the area theorem for
GW150914 if a damped sinusoid consisting of a single-mode is used at merger to
estimate the final area. This is because this model overestimates the final
mass. Including an overtone of the dominant mode decreases the confidence to
$\sim94\%$; using a full merger-ringdown model further decreases the confidence
to $\sim 85-90\%$. We find that comparing the measured change in the area to
the expected change in area yields a more robust test, as it also captures over
estimates in the change of area. We find good agreement with GR when applying
this test to GW150914 and GW170814.
