Scientists have been modeling how supermassive black holes form when two smaller black holes merge. But in their simulations, most pairs of massive black holes get stuck orbiting each other indefinitely. Now, scientists may have finally found a solution to this "final parsec problem" — and it may also help uncover the identity of one of the universe's most mysterious components.
Lurking at the heart of most ordinary galaxies is a supermassive black hole (SMBH), like the one imaged by the Event Horizon Telescope collaboration in the galaxy M87. That one is about 6.5 billion times the mass of the sun, but it wasn't always so big. Astronomers think SMBHs start out much smaller and grow into behemoths through repeated mergers with other black holes.
