First sleeping black hole on the doorstep of the Milky Way

This is the first black hole of stellar mass outside the Milky Way. There are only two types in the universe: supermassive black holes at the center of galaxies and stellar holes born from collapsed giant stars. The credit for the discovery goes to an international research team made up of numerous research centers and universities. At the top of the group of scientists is Professor Tomer Shenar. The hole was found after years of monitoring a thousand massive stars in a dwarf galaxy at the gateway to the Milky Way. Exactly the stars of the Tarantula Nebula.

Here found the first black hole of 9 solar masses, it is sleepy, that is, which emits scarce X-rays. So it is very difficult to detect. This discovery was made possible thanks to the gravitational interaction with a giant blue star with a mass 25 times that of the sun 160 thousand light-years from planet Earth. Scientists had been searching for black holes for more than two years. When they finally found him, they set out to find the cause of his presence and his sleeping nature. The reason for its inactivity is related to the proximity of a blue star. Another curiosity is that the black hole would have been born without the explosion of the supernova, its parent star.

The star that formed the black hole appears to have collapsed completely, with no signs of a previous explosion. Evidence for this “instant collapse” scenario has surfaced recently, but our study probably provides one of the most direct clues. This has huge implications for the creation of black hole mergers in the cosmos.

Tomer Shenar