GW190521: A Binary Black Hole Merger with a Total Mass of 150 M⊙

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⊙ and 66 (+17, -18) M⊙ (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65 M⊙. We calculate the mass of the remnant to be 142 (+28, -16) M⊙, 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 red shift of 0.82 (+0.28, -0.34). The inferred rate of mergers similar to GW190521 is 0.13 (+0.30, -0.11) Gpc^-3 yr^-1 .