Discover, with the participation of Hungarian researchers, the great mystery of science

According to research published in Nature, smaller black holes in flat, disk-like gas clouds that move in an elliptical orbit around giant black holes at the center of galaxies collide like billiard balls, according to a statement submitted to ELTI MTI.

It is reported that until a few years ago, our main source of information about the universe was light, until in 2015 LIGO first detected gravitational waves from the collision of a black hole.

Three Hungarian physicists participated in the research: Imre Bartos (University of Florida, former student at Eötvös Loránd), Zoltan Heymann (Columbia University, New York, former Gyorgy Beksi scholarship of Eötvös Loránd University) and Bens Kochis (former student) and assistant professor at Oxford University, Eötvös Loránd University, currently external supervisor).

But why is it surprising that two black holes do not orbit each other? They ask the question. According to Zoltán Haiman, this is due to the fundamental nature of gravitational waves. The orbits of radiating black holes become circular relatively quickly due to gravitational waves long before they collide. Previous research has shown that non-circular orbitals are very rare. This begs the question: Why would an exceptional black hole collision really occur in such an elliptical orbit?

The possible answer lies in the center of galaxies with a massive black hole millions of times heavier than the sun at the center and a flat disk-shaped gas cloud orbiting around it.

“There are also a lot of smaller black holes in this disk, and they are moving at a very high speed, because of their gravitational interaction, the black holes bounce together like billiard balls. Under these conditions, there can be no circular pairs.” Coxes Bence noted.

He added, “The presence of a central supermassive black hole alone is not sufficient to create such an environment. With doctoral students from ÁTE Szölgyén and Gergő Máthé, we previously found that black holes are arranged in a thick disk due to their weight. But frequent collisions require a thinner structure. Tagawa has shown, He is a former postdoctoral researcher at Eötvös Loránd University, that the necessary conditions can be created in galactic cores where a gas cloud exists.” Black holes can form close pairs. These objects often meet a third black hole in a chaotic dance.”

Calculations so far have assumed that the interaction of black holes occurs in three dimensions, which is true in most cases, but in this case, mostly circular pairs are formed.

“We started thinking about what would happen if black holes could move only within a flat gas cloud, which corresponds to a 2D environment. To our surprise, we found that the formation of non-circular orbits increases dramatically, up to 100 times. This theory is fully consistent with the 2019 observation. that all the special features of the GW190521 collision can be explained simultaneously by the fact that the process occurred in a flat gas cloud in the heart of a distant galaxy near a supermassive black hole,” explains Johan Samsing. This discovery also adds to a hundreds of years old problem of mechanics, the three-body problem. This process also plays an important role in how black holes collide in the hidden corners of the universe.

In addition to eccentricities, the spontaneous flat gas-pull theory explains two other surprising properties of the GW190521 collision. A large black hole mass is the result of many small black holes crammed into a gas cloud that undergo multiple collisions, increasing the mass of the resulting black hole with each collision. These successive collisions also speed up the rotation of black holes, they write.

According to the researchers, this is just the beginning. “Researchers have long been trying to understand the properties of dense, flat gas clouds, but it is a complex problem. The outcome depends largely on the properties of gas clouds and how exactly black holes move in them. Colliding black holes like GW190521 opened a new avenue that research must continue, potentially leading to More unexpected discoveries – Summarized in Zoltan Heymann’s statement.