One of the most explored objects in the universe has been discovered right here in our Milky Way galaxy.
Astronomers have found evidence of an intermediate mass at the center of a dense, globular star cluster called Omega Centauri, about 17,000 light-years away. Black HoleIt would tip the cosmic scales with a mass equivalent to at least 8,200 suns.
This is one of the strongest leads yet about this elusive beast. Black Hole This puts it in the middle mass range between stellar-mass black holes and the supermassive monsters lurking at the centers of galaxies. This is the latest in a series of phenomena detected in globular clusters, confirming that these strange collections are some of the best places to observe them.
“Here we report observations of seven fast-moving stars located 3 arcseconds (0.08 parsecs) from the center of Omega Centauri.” A team of astronomers led by Maximilian Höberle writes: of the Max Planck Institute for Astronomy in Germany.
“The speed of the fast moving stars is significantly faster than the expected central escape velocity of the cluster, so their existence can only be explained by being bound to a massive black hole. From the velocity alone we can deduce that the lower limit of the black hole’s mass is about 8,200 solar masses. This is a good example of the existence of intermediate-mass black holes in the local universe.”
Intermediate-mass black holes (IMBHs) have been scarce, at least so far: they fall into a poorly defined mass range, but typically range from about 100 to 100,000 times the mass of the Sun, or between 1 million and 1 million times the mass of the Sun.
At the smaller end of each side are stellar-mass black holes, which form from the collapse of the cores of massive stars. The merger of these black holes; Some of the larger ones are supermassive, with masses millions or even billions of times the mass of the Sun.
This is a problem because, without an IMBH, there is no “connective tissue” to bridge the two mass ranges. Astronomers believe that supermassive black holes are a slow accumulation and Hierarchical Merger Although there are many stellar-mass black holes, much more evidence of the existence of intermediate-mass black holes is needed to explain the number of supermassive black holes in the universe.
Globular clusters seem like good places to look: they are collections of millions of stars packed tightly together like glittering sardines. There are about 150 known globular clusters in the Milky Way, but their origins remain a mystery.
However, previous studies Globular clusters have expensive Concentration of There is a lump in the center is consistent with Mass range There is certainly evidence for the existence of intermediate-mass black holes. There may be something like that lurking there..
Omega Centauri is It appears to be a stripped core. The nucleus of what was once called a dwarf galaxy. Gaia SausageIt is about 150 light years in diameter and contains about 10 million stars. Dwarf galaxies are like miniature versions of full-sized galaxies, and instead of having a supermassive black hole at their center, they are tiny. Revolving around IMBH.
Now, since it’s pretty hard to find black holes just floating around in space doing nothing, searches for IMBHs in globular clusters and dwarf galaxies often rely on studying stellar kinematics – the way stars move around masses due to gravitational interactions. The most famous example is Stars orbiting a massive black hole It is located in Sagittarius A* (Sgr A*), at the centre of the Milky Way Galaxy.
Before, Research into the movement of stars Omega Centauri We found evidence that IMBH exists. What’s lurking there? That was more than a decade ago, and Hebel and his colleagues wanted to really get in there and see if they could narrow it down further.
Using 20 years of data collected by the Hubble Space Telescope – more than 500 images – the team created an updated and more detailed catalog of proper motions around the centre of Omega Centauri, searching for stars that appear to be moving as if they are being influenced by a huge, invisible mass.
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In the central region, they found several fast moving stars very similar to those orbiting Sagittarius A*, and by carefully studying their speeds and motions, they were able to determine a lower limit on the mass of the object they suspected to be interacting with: 8,200 solar masses, which is the IMBH from any angle.
In fact, the researchers say IMBH is the only plausible explanation for what they found.
“This black hole, along with other black holes discovered and stripped from more massive globular clusters, provides an important data point in the study of black hole population dynamics in low-mass galaxies. [galactic] Nuclear, They write in their papers.
“Moreover, this black hole is the nearest massive black hole and the second, after Sagittarius A*, that allows us to study the motions of multiple individual bound companion stars.”
The discovery suggests re-examining other globular clusters and applying similar methodologies to narrow down what secrets they might find, the researchers say.
This study Nature.
