Swift coalescence of supermassive black holes in cosmological mergers of massive galaxies

Understand

Supermassive black holes (SMBHs) are ubiquitous in galaxies with a sizable mass.

• It is expected that a pair of SMBHs originally in the nuclei of two merging galaxies would form a binary and eventually coalesce via a burst of gravitational waves.
• So far theoretical models and simulations have been unable to predict directly the SMBH merger timescale from ab-initio galaxy formation theory, focusing only on limited phases of the orbital decay of SMBHs under idealized conditions of the galaxy hosts.
• The predicted SMBH merger timescales are long, of order Gyrs, which could be problematic for future gravitational wave searches.