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 ∼ 5400 to 1 for equal prior odds and ∼ 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 H0=102−25+27kms−1Mpc−1 when solely analyzing GW190521 and 79.2−9.6+17.6kms−1Mpc−1 assuming prior information from the binary neutron star merger GW170817, both consistent with the existing literature.
@article{arxiv.2310.16025,
title = {GW190521: a binary black hole merger inside an active galactic nucleus?},
author = {Sophia Morton and Stefano Rinaldi and Alejandro Torres-Orjuela and Andrea Derdzinski and Maria Paola Vaccaro and Walter Del Pozzo},
journal= {arXiv preprint arXiv:2310.16025},
year = {2023}
}