Black holes are only big or small

Sometimes a black hole is like a giant cosmic beast whose mass is billions of times our sun's. Sometimes it is small, folding the sun only a few times. But is there a medium-sized black hole? A new study shows that the answer is no.

Astronauts have long asked that the most likely place to find a medium mass black hole is at the center of a miniature galaxy-like object called globular cluster. But so far no one has found it.

A group of astronauts looked at the globular cluster number RZ2109 and determined that it had no medium mass black hole. This finding suggests that the elusive medium black hole does not lurk in globular clusters, perhaps they are extremely rare.

Daniel Stern, of the NASA (California) Jet Laboratory, said: 'Some theories suggest that small black holes in globular clusters sink into the center and form a size black hole. average, but our findings prove this is not true '. Stern is the second author of the study published in the August 20 issue of the Astrophysical Journal. The main author is Stephen Zepf of Michigan State University, East Lansing.

The black hole is an extremely concentrated material place, its attraction is so strong that even light cannot escape. A black hole with a small mass is discovered about 10 times larger than the sun, which is formed when big stars explode in a supernova explosion. The heaviest black hole has billions of times the mass of the sun, it is located deep in the center of most galaxies.

The remaining medium-sized black holes are thought to be buried in the center of globular clusters. Globular clusters are dense collections of millions of stars that reside in galaxies containing hundreds of billions of stars. Theorists argue that a globular cluster should have a reduced-scale version to galactic black holes. Objects seem to be about 1,000 to 10,000 times more massive than the mass of the sun, in other words it is about the size of the black holes in the universe. In an earlier study, Zepf and his colleagues searched for evidence of a black hole in the RZ2109 globular cluster, located 50 million light years from the nearby galaxy. Using the European Space Agency's XMM-Newton telescope (the name for the X-ray Multi-Mirror design), they discovered the emitted X-ray signal of a black hole. work. But at that time they still didn't know its size.

Until now, astronauts still suspected that spherical clusters like those on photos could find medium sized black holes.They are very difficult to detect.Globular clusters are a collection of stars that move around larger galaxies like our Milky Way.Scientists analyzed a globular cluster called RZ2109 and found that it did not contain a medium-sized black hole.RZ2109 is further away from the star cluster in the photo called Omega Centauri.(Photo: NASA / JPL-Caltech / NOAO / AURA / NSF)

Zepf and Stern then teamed up with others to obtain the chemical spectrum of globular clusters using the WM Keck Observatory at Mauna Kea, Haai. The spectrum that reveals the black hole is very small, only 10 times larger than the mass of the sun.

Hypothetically, globular clusters containing a small black hole cannot have an average black hole. The medium black hole is quite heavy with a relatively large suction force, so if it really exists in the star cluster, it will quickly attract any small black hole towards it.

Stern said: 'If a medium black hole exists in globular clusters, or it will swallow small black holes or kick them out of the globular cluster'. In other words, the small black hole in the cluster RZ2109 eliminated the possibility of a medium black hole.

How can a scientist detect the black hole in a globular cluster immediately? Using modeling techniques, Zepf and his colleagues concluded that the obtained spectrum revealed high-velocity physical currents, or wind, flowing from the black hole. Only small black holes can flush out the observed strong winds.

Zepf explained: 'From X-ray data, we learned that this black hole is swallowing matter. If an average black hole swallowed material, it would be a great bargain for it. But with a small black hole it is different, with it being too much, some material will be discharged in the form of high velocity winds. High velocity winds are proof that the black hole is small. '

Is this the end of the story of the average black hole? According to Zeft, they may be lurking somewhere outside the galaxies like our Milky Way; or in dwarf galaxies, it is also possible that the remnants of dwarf galaxies have been annexed by the larger galaxy. If this is the case, the medium sized black hole is very faint and hard to detect.

Other authors of the study include: Thomas Maccarone of the University of Southampton, United Kingdom; Arunav Kundu of Michigan State University; Marc Kamionkowski of California Institute of Technology, Pasadena; Katherine Rhode and John Salzer of Indiana University, Bloomington; along with Robin Ciardullo and Caryl Gronwall of Penn State University, University Park, Pa. Salzer also works at Wesleyan University, Middleton, Conn.