Black Hole up to 100 Billion Times Mass of Sun is Missing
This image from Abell 2261 includes X-ray data from Chandra (pink) showing hot gas pervading the cluster, as well as optical data from Hubble and the Subaru Telescope showing galaxies in the cluster and in the background. With these telescopes, astronomers searched the galaxy in the center of the image for evidence of a black hole that weighs between 3 and 100 billion times the Sun and is expected to be there. No evidence of this black hole was found, adding to the mystery of what is happening in this system. X-ray: NASA / CXC / University of Michigan / K. Gültekin; Optical: NASA / STScI and NAOJ / Subaru; Infrared: NSF / NOAO / KPNO; Radio: NSF / NOAO / VLA
You’d think it would be hard to lose one of the largest black holes in the universe. Right now, however, scientists are puzzled by the apparent lack of the supermassive black hole at the center of the Abell 2261 galaxy cluster – a monster estimated to weigh between 3 and 100 billion times the mass of the Sun.
At the center of almost every galaxy, including our own, is a supermassive black hole. These black holes usually scale with the size of the galaxy. The bigger the galaxy, the bigger the black hole. Abell 2261, which is 2.7 billion light years away, has a very large central galaxy and should therefore have a similarly sized supermassive black hole. Oddly enough, astronomers couldn’t find this particular black hole anywhere.
This ongoing puzzle has led Abell 2261 to be studied by a variety of instruments over the years, including the Subaru Telescope, Hubble Space Telescope, and Chandra X-ray Observatory. A previous study used data from Chandra to look for X-rays generated by matter when it falls into the black hole and becomes overheated, but found no such evidence.
This is very strange indeed, and the latest study examined Chandra’s data in more depth. It looked for evidence that the black hole had somehow been ejected from its position in the center of the galaxy. While the study found no evidence for the black hole itself, it found some evidence that a merger might have occurred.
A merger is a dramatic event in which two galaxies merge and the central black holes of each galaxy also merge, creating waves known as gravitational waves. If these waves weren’t evenly distributed in all directions, the black hole could have moved away from its place in the heart of the galaxy.
This suggestion, dubbed the “recoiling black hole,” is only theoretical as nothing like it has been seen before. But if it’s true, it could offer scientists an exciting new way to study gravitational waves.