Astrophysics (index)

Final Parsec Problem

(Last Parsec Problem)
(lack of a convincing theory on how SMBHs can reach each other)

The Final Parsec Problem (or Last Parsec Problem) is an astrophysical problem regarding the merger of two Supermassive Black Holes (SMBH), e.g., after a Galaxy Merger. When the Black Holes (BH) are extremely close, they merge because Gravitational Waves (GW) significantly bleed their orbital energy. Outside that, close encounters with stars can remove energy. However, the odds of encountering a star decreases as the orbit decreases, to a point where they would remain in virtually the same orbit, i.e., the Timescale for further decrease is far too long. Assuming they sometimes do merge, it is not clear how their orbits continue to become smaller through the final Parsec (pc).

(black holes,mergers)