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Free keywords:
General Relativity and Quantum Cosmology, gr-qc, Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
In this paper we present an extensive analysis of the GW190521 gravitational
wave event with the current (fourth) generation of phenomenological waveform
models for binary black hole coalescences. GW190521 stands out from other
events since only a few wave cycles are observable. This leads to a number of
challenges, one being that such short signals are prone to not resolve
approximate waveform degeneracies, which may result in multi-modal posterior
distributions. The family of waveform models we use includes a new fast
time-domain model IMRPhenomTPHM, which allows us extensive tests of different
priors and robustness with respect to variations in the waveform model,
including the content of spherical harmonic modes. We clarify some issues
raised in a recent paper [Nitz&Capano], associated with possible support for a
high-mass ratio source, but confirm their finding of a multi-modal posterior
distribution, albeit with important differences in the statistical significance
of the peaks. In particular, we find that the support for both masses being
outside the PISN mass-gap, and the support for an intermediate mass ratio
binary are drastically reduced with respect to what Nitz&Capano found. We also
provide updated probabilities for associating GW190521 to the potential
electromagnetic counterpart from ZTF.
