Milky Way’s Supermassive Black Hole Might Be Surrounded By A Swarm Of 10,000 Smaller Black Holes, Study Finds


A new study by Columbia University suggests that 10,000 smaller black holes surround the supermassive black hole at the core of the Milky Way.

According to a report by Science Daily, researchers discovered a dozen black holes surrounding the SMBH in the middle of the Milky Way, Sagittarius A. This supports predictions that smaller black holes surround a much larger black hole.

Chuck Hailey, the study’s lead author and a co-director of the university’s astrophysics lab, explains that studying the distribution makes it possible to learn the interaction between bigger black holes and the smaller black holes.

Understanding Black Holes

For years, scientists have been looking for evidence that much smaller black holes surround supermassive ones located at the core of large galaxies. The Columbia University study which appears in the April 5 issue of the journal Nature aims to shed light on this theory.

As Hailey explains, the most accessible place to prove this theory is by studying the closest supermassive black hole to Earth, Sagittarius A.

“There are only about five dozen known black holes in the entire galaxy — 100,000 light years wide — and there are supposed to be 10,000 to 20,000 of these things in a region just six light years wide that no one has been able to find. There hasn’t been much credible evidence.”

The Search For Black Holes

The most common method to look for black holes is to look for bursts of X-ray glow which occurs in some black hole binaries. According to Hailey, this is the obvious way to search for black holes located in the Galactic Center. However, bursts which are bright and strong enough can only be seen in 100 to 1,000 years. Hence, his team devised another method — looking for X-rays emitted by binaries that are in an inactive state. These emissions are fainter but steadier.

These emissions indicate the mating between a low mass star and a black hole, hence proving a more viable way of knowing what lies in the Galactic Center.

“Isolated, unmated black holes are just black — they don’t do anything. So looking for isolated black holes is not a smart way to find them either. But when black holes mate with a low mass star, the marriage emits X-ray bursts that are weaker, but consistent and detectable. If we could find black holes that are coupled with low mass stars and we know what fraction of black holes will mate with low mass stars, we could scientifically infer the population of isolated black holes out there.”

Based on the data from Chandra X-ray Observatory, the team tested the technique and searched for X-ray signatures indicating the fusion between a black hole and a low mass binary in an inactive state. Within three light years of the supermassive black hole, they found 12 black holes-low mass binaries.

The spatial distribution of the emissions they tracked indicates that there are about 300 to 500 black hole and low mass binaries and approximately 10,000 black holes in the area close to the Sagittarius A.

Discovering the existence of these 10,000 black holes surrounding the supermassive black hole Sagittarius A will be a valuable tool in the advancement of gravitation wave research and other studies involving the universe.