GW190521: A Binary Black Hole Merger with a Total Mass of $150 ~ M_{\odot}$

TL;DR

The paper reports the detection of GW190521, a gravitational-wave signal from a binary black hole merger with a total mass of about 150 solar masses, including an intermediate mass black hole, and discusses its implications for black hole formation.

Contribution

This study presents the first observation of a black hole merger with a total mass around 150 solar masses, including a primary black hole in the pair-instability mass gap.

Findings

Detected a gravitational-wave signal with high confidence.

Inferred the primary black hole mass likely within the pair-instability gap.

Estimated the remnant black hole as an intermediate mass black hole.

Abstract

On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of $85^{+21}_{-14} M_{\odot}$ and $66^{+17}_{-18} M_{\odot}$ (90 % credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, and has only a 0.32 % probability of being below $65 M_{\odot}$. We calculate the mass of the remnant to be $142^{+28}_{-16} M_{\odot}$, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is $5.3^{+2.4}_{-2.6}$ Gpc, corresponding to a redshift of $0.82^{+0.28}_{-0.34}$. The inferred rate of mergers similar to GW190521 is $0.13^{+0.30}_{-0.11}\,\mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$.