The supermassive black holes in the centers of the Milky Way and the Andromeda galaxies are doomed to engulf each other in a failed cosmological dance.
Astronomers have long known that Andromeda is on a collision course with our galaxy (SN: 31/05/12). But not much is known about what will happen to the black holes that each galaxy harbors in its core. New simulations reveal their final destination.
The galaxies will merge into a giant elliptical galaxy – nicknamed "Milkomeda" – in about 10 billion years. Then the central black holes will begin to orbit each other and eventually collide less than 17 million years later, researchers propose on Feb. 22 at arXiv.org and in a previous article published in Astronomy & Astrophysics Just before the black holes if they break, they will radiate gravitational waves with the power of 10 quintillions of suns (SN: 2/11/16). Researchers estimate that any civilization less than 3.25 million light-years from us that has gravitational wave detection technology on par with our current abilities would be able to detect collision.
The latest data suggests that Andromeda is approaching us at about 116 kilometers per second, says Riccardo Schiavi, an astrophysicist at Sapienza University in Rome. Using computer simulations that include the gravitational attraction of the two spiral galaxies on each other, as well as the possible presence of scarce gas and other material between them, Schiavi and his colleagues played out how the galactic collision would develop.
A computer simulation shows how the Milky Way (left) and Andromeda (right) galaxies will pass each other about 4 billion years before merging into a single galaxy about 6 billion years later. The numbers along the sides denote the distance in kiloparsecs (1 kiloparsec is equivalent to 3,260 light-years).
Previous simulations have suggested that Andromeda and the Milky Way are scheduled for a frontal collision in about 4,000 to 5 billion years. But the new study estimates that the two star groups will shoot up very close about 4.3 billion years and merge completely about 6 billion years later.
The team’s estimate for the Milkomeda merger date “is a little longer than other teams have found,” says Roeland van der Marel, an astronomer at the Space Telescope Science Institute in Baltimore who did not participate in the research. However, he points out, this could be due in part to uncertainty in measuring the speed of Andromeda across the sky.