Astronomers Find Two Giant Black Holes Spiraling Toward a Collision

In this illustration, light from a smaller black hole (left) curves around a larger black hole and forms an almost-mirror image on the other side. The gravity of a black hole can warp the fabric of space itself, such that light passing close to the black hole will follow a curved path around it. Credit: Caltech-IPAC


Evidence that this supermassive black hole may have a companion comes from observations by radio telescopes on Earth. Black holes don’t emit light, but their gravity can pack disks of hot gas around them and expel some of that material into space. These jets can span millions of light years. A stream heading toward the ground appears brighter than a stream moving away from the ground. Astronomers call supermassive black holes with jets directed toward Earth, and an explosion called PKS 2131-021 is at the center of this latest research paper.

Located about 9 billion light-years from Earth, PKS 2131-021 is one of 1,800 squares that a group of researchers from the California Institute of Technology in Pasadena has been monitoring with the Owens Valley Radio Observatory in Northern California. for 13 years as part of a general study of plaza behavior. But this particular blazar exhibits strange behavior: its brightness shows regular ups and downs, as predictable as the ticking of a clock.

The researchers now believe that this regular difference is the result of a second black hole gravitating toward the first as they orbit each other every two years. The mass of each of the black holes in PKS 2131-021 is estimated to be a few hundred million times the mass of our Sun. To confirm the result, scientists will try to detect gravitational waves – Ripples in space – coming from the system. . The first detection of gravitational waves from black hole binaries was announced in 2016.

To make sure the oscillations weren’t random or causing a temporary effect around the black hole, the team had to look beyond the decade (2008 to 2019) of data from the Owens Valley Observatory. After learning that two other radio telescopes had also studied this system, the University of Michigan Radio Observatory (1980 to 2012) and the Haystack Observatory (1975 to 1983), they investigated the additional data and found that it matched expectations for how the Blazer would explode. The brightness should change over time.