A single ejection of a black hole has created giant clouds of gas near the Milky Way

(ORDO NEWS) — Astronomers from the United States and China have found that the so-called ears of the Milky Way – giant clouds of hot gas, discovered by the Spektr-RG and Fermi telescopes, were generated by a single burst of activity from a supermassive black hole in the center of the Galaxy. The results of the scientists’ calculations were published in an article in the journal Nature Astronomy.

“We have created a theoretical model that links the existence of these hot gas ejections, as well as some features in the galaxy’s microwave background radiation, to a single burst of activity from a supermassive black hole that occurred approximately 2.6 million years ago. The validity of our model is confirmed by the results of computer simulations” , the researchers write.

The so-called ears of the Milky Way – giant bubbles of gas emitting large amounts of gamma rays – were discovered by the Fermi orbiting telescope in 2010. In subsequent years, astronomers discovered similar structures near the nearby Andromeda Nebula, and also found hints of their existence in the vicinity of other spiral galaxies.

Two years ago, bubbles of hot gas, similar in size, emitting X-ray beams, were discovered in the same region of space using the German eRosita telescope installed on board the Russian orbital observatory Spektr-RG. Their discovery confirmed the existence of the “ears” of the Milky Way and indicated that they were generated by the supermassive black hole Sgr A *, located at the center of the Galaxy.

Traces of black hole activity

A group of astrophysicists led by Ellen Zweibel, a professor at the University of Wisconsin-Madison (USA), proposed a theoretical explanation of how these giant gas structures could have arisen. To do this, scientists have created a detailed model of the center of the galaxy and the black hole Sgr A *, periodically interacting with stars and other clusters of matter.

As the scientists note, X-rays and other data obtained using the Spektra-RG instruments played a key role in preparing this model and determining the possible progenitor of the Milky Way’s “ears”, which in the past was claimed not only by Sgr A * emissions, but also supernova explosions.

The calculations by Prof. Zweibel and her colleagues unequivocally showed that giant gas accumulations were ejected into the intergalactic medium as a result of a single awakening of a supermassive black hole, which happened about 2.6-3 million years ago. According to current scientists, this episode of activity lasted about 100 thousand years – a relatively short time by the standards of galaxies and supermassive black holes.

According to the researchers, the theory they developed may receive additional confirmation after the European X-ray telescope ATHENA is launched into orbit. It will have sufficient sensitivity and resolution to measure the rate at which the boundaries of the “ears” of the Galaxy are expanding, and to prove that these ejecta were generated by a burst of Sgr A* activity.


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