The hunt is on in neighboring galaxy for 2nd closest monster black hole to Earth - Space.com

Astronomers may finally have a way to hunt for a monstrous supermassive black hole they suspect lurks in the dwarf galaxy next door.

The behemoth would be the second closest supermassive black hole to Earth, after Sagittarius A* (Sgr A*) at the heart of the Milky Way, in the companion galaxy Leo I.

This neighboring supermassive black hole, named Leo I*, was first proposed to exist in 2021, when astronomers noticed stars accelerating as they approached the heart of the dwarf galaxy.

While this is good evidence in favor of a supermassive black hole, astronomers frustratingly couldn't get a direct image of emissions from Leo I* to prove it exists.

This is the case with Leo I*: Its dwarf galaxy doesn't have enough gas to feed the supermassive black hole, leaving it inactive and in effect invisible.

In particular, a detection would resolve another astronomical mystery: whether dwarf galaxies possess supermassive black holes of these tremendous masses at all!

(Scientists estimate that Leo I* might be on the order of 3 million times more massive than the sun; the Milky Way's black hole, Sgr A*, is only a bit larger, at 4 million times the mass of the sun.)!

"It would be the second-closest supermassive black hole after the one at the center of our galaxy, with a very similar mass but hosted by a galaxy that is a thousand times less massive than the Milky Way," Loeb said in the statement.

In the case of the Milky Way and the supermassive black holes at the heart of most large galaxies, that central object contains about a 10th of the total mass of the sphere of stars that surround it.

— Sagittarius A* in pictures: The 1st photo of the Milky Way's monster black hole explained in images.

This is the first photo of the Milky Way's monster black hole Sagittarius A* .

"Instead, Leo I appears to contain a black hole a few million times the mass of the sun, similar to that hosted by the Milky Way.