Astronomers discover that a galaxy orbiting the Milky Way is home to a supermassive black hole

Posted: Dec 5, 2021 05:54 GMT

According to the researchers, this is the second closest known supermassive black hole after the one at the center of our galaxy.

Astronomers have recently discovered that a small satellite galaxy orbiting the Milky Way is home to an unusually massive black hole.

According to a study published in The Astrophysical Journal, the central region of the dwarf galaxy Leo I it has a supermassive black hole, compared to the mass of the galaxy. This has around 3.3 million solar masses, about 16% of the total mass of the galaxy.

Although there is a large margin of uncertainty, the result is still a great surprise. That size is quite close to the Sagittarius mass A *, the supermassive black hole located at the heart of the Milky Way. It has about 4 million solar masses, and recent calculations put the Milky Way’s mass at about 1.3 trillion solar masses.

María José Bustamante, a researcher at the University of Texas and co-author of the study, told Newsweek that this discovery has several notable characteristics: “It is the second closest known supermassive black hole, the first being the one found in the center of our galaxy. And it lives inside a dwarf spheroidal galaxy, which are galaxies that shouldn’t have supermassive black holes inside. “

The team of astronomers arrived at their discovery by studying how the density of dark matter changes from the outer edge of Leo I to its center. This is achieved by measuring the gravitational influence of the dwarf galaxy’s dark matter content on its stars.

Leo I is a dwarf spheroidal galaxy located about 820,000 light years in the constellation Leo. The researchers chose to study it because it appears to have very little dark matter, unlike other galaxies that orbit the Milky Way.

“The models show that you need a black hole in the center of the galaxy – you don’t really need a lot of dark matter,” said Karl Gebhardt, an astronomer at the University of Texas at Austin. He added that the results are important, since “astronomers have used galaxies like Leo I, called dwarf spheroidal galaxies, for 20 years to understand how dark matter is distributed within galaxies.”

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