An international team of scientists has published an explanation for the gravitational wave burst GW190521 for the first time.
The most powerful collision between black holes ever recorded by science is the gravitational wave event GW190521.
This event is unique in that it was caused by the merger of a pair of supermassive black holes that were not in a circular orbit. Astronomers have concluded that a two-dimensional accretion disk played a major role in this merger.
The merger occurred 7 billion years ago at a distance of 17 billion light years from Earth. This is the most distant recorded merger known. The position of the signal source is determined by the sky area of 765 square meters. degrees in the constellations Coma Berenices, Canis Hounds and Phoenix.
It turned out that the objects in GW190521 were heavier than the limit considered possible by the weight of a black hole, and the event also caused a flash. Various possible explanations for these two features have since been given, but gravitational waves have also revealed a third unusual fact—black holes didn’t orbit each other before merging.
Our work has shown that the gaseous disk plays an important role in trapping smaller black holes that approach the supermassive black hole at the center over time, as well as each other. Over time, they meet and form pairs, and even such a pair can begin to interact with a third and even a fourth black hole.
Hiromichi Tagawa, study co-author at Tohoku University
The authors of the new work decided to consider the case of interaction of black holes in a flat two-dimensional disk. It turned out that in this case the probability of merging black holes with an eccentric orbit increases by 100 times.
This means that about half of the black hole mergers in such disks will be eccentric. Such a conclusion may explain why the objects had a huge mass: it appeared as a result of successive mergers of black holes inside the accretion disk. And the flash was formed from the gas surrounding them.