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arXiv · 2310.16025

GW190521: a binary black hole merger inside an active galactic nucleus?

Sophia Morton·Stefano Rinaldi·Alejandro Torres-Orjuela·Andrea Derdzinski·Maria Paola Vaccaro·Walter Del Pozzo
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Abstract

GW190521, the most massive binary black hole merger confidently detected by the LIGO-Virgo-KAGRA collaboration, is the first gravitational-wave observation of an intermediate-mass black hole. The signal was followed approximately 34 days later by flare ZTF19abanrhr, detected in AGN J124942.3+344929 by the Zwicky Transient Facility at the 78% spatial contour for GW190521s sky localization. Using the GWTC-2.1 data release, we find that the association between GW190521 and flare ZTF19abanrhr as its electromagnetic counterpart is preferred over a random coincidence of the two transients with a log Bayes factor of 8.6, corresponding to an odds ratio of $\sim$ 5400 to 1 for equal prior odds and $\sim$ 400 to 1 assuming an astrophysical prior odds of 1/13. Given the association, the multi-messenger signal allows for an estimation of the Hubble constant, finding $H_0 = 102^{+27}_{-25}\mathrm{\ km \ s^{-1} \ Mpc^{-1}}$ when solely analyzing GW190521 and $79.2^{+17.6}_{-9.6}\mathrm{\ km \ s^{-1} \ Mpc^{-1}}$ assuming prior information from the binary neutron star merger GW170817, both consistent with the existing literature.

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Sophia Morton, Stefano Rinaldi, Alejandro Torres-Orjuela, Andrea Derdzinski, Maria Paola Vaccaro, Walter Del Pozzo. 2023-10-24. GW190521: a binary black hole merger inside an active galactic nucleus?. https://arxiv.org/abs/2310.16025

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