Two orbiting black holes will soon collide in a violent merger

The discovery is the culmination of 13 years of observations.
Chris Young
An artist's concept of the merging black holes.Caltech/R. Hurt (IPAC)

Two space giants will soon collide. Astronomers from Caltech detected two black holes, 9 billion light-years from Earth, on the verge of a violent merger, a press statement reveals. 

The observations, which were made over the course of 13 years by astronomers at the Owens Valley Radio Observatory in Northern California, reveal that a previously-observed radio black hole at the center of its quasar, PKS 2131-021, has a companion black hole, making it a supermassive black hole binary. Quasars are active galactic cores in which supermassive black holes siphon material from an accretion disc.

The two supermassive black holes appear to be orbiting each other once every two years, according to Caltech’s report. Each of the colossal space objects has a mass hundreds of millions of times larger than our Sun, and they are separated by a distance roughly 50 times larger than the space between our Sun and Pluto. Their findings are published in a paper in the Astrophysical Journal Letters.

Colliding galaxies

The two black holes are expected to merge in approximately 10,000 years (a short time on the cosmic scale) leading to a violent collision that is expected to send gravitational waves cascading across the universe. In November, in fact, astronomers from the University of Colorado Boulder released their report on computer simulations of two black holes at the center of two galaxies colliding. They claimed that the impact could cause a "gravitational kick" so powerful that it could distort the shape of a galaxy.

The astronomers made their discovery when they found a powerful jet was emanating from the vicinity of the black holes. The jet was observed to be shifting back and forth, an indication of the pair’s orbital motion that could be detected via periodic shifts in the brightness of radio-light emanating from the black holes. The newly-discovered pair of black holes is the second known candidate for a pair of supermassive black holes caught on the verge of colliding. The first pair, discovered within a quasar called OJ 287, orbit each other once every nine years.

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The researchers explain that their discovery will help to better understand these violent processes that are capable of altering the shape of entire galactic structures. In doing so, they can a better understanding of our own galaxy's cannibalistic past.

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