Collisions among galaxies were historically assumed to inevitably contribute to the enormous black holes' activity at their cores. However, researchers have carried out the most reliable simulations of several collision scenarios and noticed that certain collisions would decrease their central black holes' operation. The explanation is that specific head-on impacts will help clear the matter from the galactic nuclei that would otherwise feed the black holes found inside.

A Simulation of Two Colliding Stars Reveal How A Black Hole is Born
(Photo: NASA official website)

Suppose you think of gargantuan events such as the merger between worlds. In that case, it may be easy to picture it as a form of galactic cataclysm, of stars falling and bursting, and catastrophe on an epic scale. Although it's really similar to merging a pair of clouds, typically, a bigger one replaces a smaller one. It's doubtful that the stars between them would clash. But that said, the effects can be immense as universes clash.

Are These Clashes Unavoidable?

Galaxies clash in various forms. A tiny galaxy can often intersect with the outer portion of a larger one and then move through or combine, sharing a number of objects along the way in either situation. But galaxies will clash head-on as well, where the smaller of the two would be ripped apart by the larger one's overpowering tidal forces. It is in this condition where, inside the galactic nucleus, something rather fascinating will happen.

Research Associate Yohei Miki of Tokyo University said a massive black hole (MBH) sits at the center of several galaxies. Experts believe that a crash would often supply an MBH with fuel in the form of material inside the nucleus. 

And that this fuel will feed the MBH, growing its operation dramatically, which we will see as, among other things, ultraviolet and X-ray radiation. We have sufficient cause now, though, to assume that this chain of events is not unavoidable and that the very reverse can also be valid in fact.

ALSO READ: Massive Black Hole Found in the Milky Way

Galaxy Collision Can Leave the Black Holes With Nothing to Feast On

Miki informs MailOnline that, compared to black holes at the center of other galaxies, the large black hole's activity frequency at the heart of the Milky Way is comparatively mild. Still, Miki and his group were intrigued to examine this idea. They developed extremely accurate simulations of scenarios of galactic collisions and ran them on supercomputers.

The team was delighted to see that an approaching small galaxy might potentially strip away the matter surrounding the MBH from the larger one in certain circumstances. This will decrease its operation rather than raise it.

"In a torus, or donut, form, we measured the complex evolution of the gaseous matter surrounding the MBH," Miki said. If this torus were accelerated by the incoming galaxies beyond a certain level defined by the MBH's properties, the matter would be expelled. The MBH would be starving. While we are still uncertain about how long the repression of MBH behavior may continue, these occurrences may last in the area of a million years.

This analysis could help us consider our own Milky Way evolution. Astronomers are sure that our universe has crashed before with several smaller ones.

Experts published their findings in the journal Nature Astronomy. 

ALSO READ: Massive Black Hole Collisions Are Giving Off Detectable Galactic X-ray and Gravitational Waves

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