2026-09-05 15:49:16 UTC
JD 2461289.16
STATION 04 · MULTI-MESSENGER WIRE DOSSIER Gravitational Wave CONFIRMED

GW190521

“Intermediate-Mass Black Hole Formation in the Pair-Instability Gap”
LIGO Hanford, LIGO Livingston & Virgo Trigger: 2019-05-21 03:02:29 UTC
ASTROPHYSICAL LOCALIZATION & TELEMETRY
FRAME: ICRS / J2000
Sky Coordinates 12h 49m 36.0s -26° 48' 00" (192.40000°, -26.80000°)
Cosmological Redshift z = 0.8200 Luminosity Dist: 17.3 Billion ly (5.3 Gpc)
Constellation / Field Coma Berenices / Virgo Host Field Environment
Detection Significance SNR 14.7 (FAR < 1 in 4,900 yr) Multi-detector confidence
chirp mass
64 M☉
primary mass
85 (+21 / -14) M☉ (Upper Mass Gap)
secondary mass
66 (+17 / -18) M☉
remnant mass
142 (+28 / -16) M☉ (Intermediate-Mass BH)
energy radiated
8.0 M☉c² in pure gravitational waves
luminosity dist
5.3 Gpc (z ~ 0.82)
merger type
Binary Black Hole (BBH)

01 Scientific Overview & Source Physics

A short-duration gravitational wave burst (approx. 0.1 seconds) resulting from the collision of two massive black holes of 85 M☉ and 66 M☉. The primary black hole fell directly inside the pair-instability supernova mass gap, where stellar core-collapse theoretically cannot produce remnants. The remnant was a 142 M☉ intermediate-mass black hole.

02 Multi-Messenger Follow-Up Campaign Matrix

Observatory / Instrument Spectral Regime Observational Detection & Counterpart Findings
ZTF
Optical (g, r)
Candidate optical flare in AGN J1249+3449 investigated as potential accretion disk kick counterpart.
Fermi LAT
High-energy Gamma
No high-energy counterpart observed.