Astronomers have discovered a 100,000-solar-mass black hole hidden in the Andromeda galaxy, inside a large star cluster: it’s a rare case among so-called intermediate-mass black holes.
An international group of astronomers has discovered a black hole like no other. At 100,000 solar masses, it is smaller than black holes that have been found in the centers of galaxies, but larger than black holes that are born when stars explode and create supernovae. This makes it one of the few confirmed intermediate-mass black holes: It was hidden inside B023-G078, a huge star cluster in our nearest neighbor galaxy Andromeda.
The Andromeda Galaxy, also known as Messier 31, is 220,000 light-years in diameter considering its galactic halo and about 150,000 light-years between the ends of its arms. In addition to being the closest spiral galaxy to the Milky Way, it is also the farthest object visible to the naked eye from Earth: it is 2.5 million light-years from us.
Astronomers have discovered a 100,000-solar-mass black hole hidden in the Andromeda galaxy, inside a large star cluster: it’s a rare case among so-called intermediate-mass black holes.
An international group of astronomers has discovered a black hole like no other. At 100,000 solar masses, it is smaller than black holes that have been found in the centers of galaxies, but larger than black holes that are born when stars explode and create supernovae. This makes it one of the few confirmed intermediate-mass black holes: It was hidden inside B023-G078, a huge star cluster in our nearest neighbor galaxy Andromeda.
The Andromeda Galaxy, also known as Messier 31, is 220,000 light-years in diameter considering its galactic halo and about 150,000 light-years between the ends of its arms. In addition to being the closest spiral galaxy to the Milky Way, it is also the farthest object visible to the naked eye from Earth: it is 2.5 million light-years from us.
Along with our own galaxy, it is considered the largest and brightest of the galaxies that make up the local group, made up of about 30 small galaxies plus three large spiral galaxies: Andromeda, the Milky Way and the Triangulum Galaxy. As Andromeda approaches the position of the Milky Way at about 300 kilometers per second, some specialists say that the two galaxies will collide in about 5.86 billion years and form an even larger galaxy, when “an event called a lactome.
A great galactic dump
Now, a team of astronomers led by Renuka Pechetti of Liverpool John Moores University in the UK and Anil Seth of the University of Utah in the US has confirmed the discovery of an intermediate-mass black hole in the galaxy of Andromeda, who had previously been confused. for globular star cluster, known as B023-G078.
In fact, scientists have verified that B023-G078 is not a globular cluster of stars but a bare core. According to a press release, specialists call the remnants of small galaxies that fall into the networks of other larger galaxies bare or stripped nuclei: the outer stars are pulled apart by gravitational force, creating a small, dense core that orbits around the largest galaxy. Precisely, in the center of this nucleus will live a black hole.
Using new observational data provided by the Gemini Observatory and images from the Hubble Space Telescope, astronomers have confirmed that B023-G078 is a kind of large garbage dump with about 6.2 million solar masses, in which the remains of galaxies end up. that make up the entire system. In this framework, stars in bare cores are more complex than in globular clusters: these features are seen in B023-G078.
Therefore, at its center is not a “classic” black hole, but one of the strangest and most difficult to identify: an intermediate-mass black hole. Black holes with masses up to 100 solar masses and supermassive black holes that rule the centers of galaxies, with millions of solar masses, are generally more easily identified by astronomers. By contrast, intermediate-mass black holes are about 100,000 solar masses.
According to the conclusions of the new study, recently published in The Astrophysical Journal, the discovery of the bare nucleus and the intermediate-mass black hole will allow us to deepen our understanding of the merger between large and small galaxies, a phenomenon that has marked the history of the Universe. and will continue to do so in the future.
Reference
Detection of a 100,000 M ⊙ black hole in the more massive globular cluster of M31: a tidally stripped core. Renuka Pechetti et al. The Astrophysical Journal (2022). DOI: https://doi.org/10.3847/1538-4357/ac339f