The dimensions of galaxies in mergers affect the "inclusion" of black holes

The dimensions of galaxies in mergers affect the

A shot from NASA's Hubble Space Telescope demonstrates the territory of the massive galactic cluster Abell 2744. Here you can see some of the tiniest and youngest galaxies

A new study from the University of Colorado (Boulder) shows that powerful blows can seem much more effective when activating black holes. When two galaxies collide, the central supermassive black holes also break. But before that, galaxies often begin to flicker, absorbing huge amounts of gas and dust and creating an active galactic nucleus (AGN).

But not all mergers can be considered equal. In some, only one black hole is active. The researchers found that single activations occur more frequently in impacts with incompatible galaxies (one is huge and the other is tiny).

For the analysis, information from the Chandra X-ray Observatory, which systematically scan the night sky for signatures of active galactic nuclei, was used. They noticed a merger in the search for off galaxies (with one AGN). The absence of symmetry suggests that a second supermassive black hole that did not turn on may be nearby. Scientists took a sample of 10 off the galaxies and compared with pairs of AGN. It turned out that in 9 out of 10 galaxies, only one active black hole emanated from one-way mergers or when one galaxy was 4 times larger than the second. Only 2/3 of the galaxies with two AGNs collided with similar in size.

It turned out that in a collision of two galaxies of approximately the same size, their black holes affect each other by powerful gravitational forces. They send gas and dust clouds captured by black holes. If the galactic parameters in the merging pair differ sharply, then we get less forces affecting gas and dust.

The team did not identify the reasons why the black hole was activated during the disproportionate merger. Sometimes it was a huge black hole, while in others it was smaller. Scientists will focus on how the destruction of two black holes affects the galaxies themselves, namely the process of creating and destroying stars.

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