Electromagnetic signals following stellar-mass black hole mergers

Understand

It is often assumed that gravitational wave (GW) events resulting from the merger of stellar-mass black holes are unlikely to produce electromagnetic (EM) counterparts.

• We point out that the progenitor binary has probably shed a mass $\gtrsim 10\,{\rm M}_{\odot}$ during its prior evolution.
• If a tiny fraction of this gas is retained until the merger, the recoil and sudden mass loss of the merged black hole shocks and heats it within hours of the GW event.
• Whether resulting EM emission is detectable is uncertain.