Runaway Star reveals hidden black holes of the Milky Way’s most recent neighbor

Astronomers have discovered strong evidence of the closest super-large black holes outside the Milky Way galaxy. This huge black hole is found in the large Magellan cloud, one of our closest galaxy neighbors to ourselves.

To make this discovery, researchers followed the path with ultra-fine accuracy of 21 stars on the outskirts of the Milky Way. These stars travel so fast that they can escape the gravity clutches of the Milky Way and nearby galaxies. Astronomers call these “Hyper Belt Rates” stars.

Just as forensic experts can replicate the origins of bullets based on their orbit, researchers have determined where these superfast stars came from. They found that about half of them linked to an ultra-large black hole in the heart of the Milky Way. But the other half came from somewhere else: a massive previously unknown black hole in the large Magellan Cloud (LMC).

“Cosmologically speaking, it’s amazing that we realize there’s another super-large black hole just below the block,” said Jesse Han of the Center for Astrophysics. Harvard & Smithsonian (CFA) led the new research. “Black holes are so stealthy that this has been under our noses this time.”

Researchers used data from the European Space Agency’s Gaia Mission to discover the secret black hole. This is a satellite that tracks over a billion stars across the Milky Way with unprecedented accuracy. They also used improved understanding of LMC trajectories around the Milky Way, which were recently obtained by other researchers.

“We knew these superfast stars had been around for a while, but Gaia gave us the data we needed to figure out where they actually came from,” said Kareem El Budley, co-author of Caltech in Pasadena, California. “Combining these data with a new theoretical model of how these stars move, we made this incredible discovery.”

If the Double-Star System is too close to a superstar black hole, Hypervelocity Stars will be created. A violent gravitational pull from a black hole tears two stars and captures one star in a nearby orbit around it. Meanwhile, other orphan stars are abandoned at speeds over millions of miles per hour, creating super-fast stars.

An important part of the team’s research was theoretical model prediction that the LMC’s ultra-large black holes would create clusters of super-fast star stars in one corner of the Milky Way, due to how the LMC moves around the Milky Way. Stars ejected along the direction of LMC movement should receive an additional boost in speed. In fact, their data revealed the existence of such clusters.

The team discovered that hypervariance star properties cannot be explained by other mechanisms, such as stars being ejected when their ally receives a supernova explosion, or that stars being ejected by mechanisms like the double star system.

“The only explanation we can come up with for this data is the presence of a monster black hole in the next Galaxy,” said CFA co-author Scott Lucchini. “So, in our universe, we’re not just the super-large black holes in the Milky Way that drive stars out of the galaxy.”

Using the star velocity and the relative numbers discharged by the LMC and Milky Way supermassive black holes, the team determined that the LMC black holes had a mass of about 600,000 times the mass of the sun. For comparison, the ultra-high-heavy black holes of the Milky Way have solar masses of around 4 million people. Elsewhere in the universe are ultra-large black holes, with billions of times more mass than the sun.

The paper describing these results is accepted because it has been published in The Astrophysical Journal. The backup version will be displayed on the ARXIV prelint server.