An image shows that an event of surprising power occurred near the center of the Milky Way

Radio image of the center of the Milky Way with part of the MeerKAT telescope network in the foreground. The plan of the galaxy is marked by a series of bright elements, exploded stars and regions where new stars are being born, and diagonally crosses the image from the bottom to the right up to In the upper center. The black hole in the center of the Milky Way is hidden in the brightest of these extensive areas. The radio bubbles extend from the two nearest antennas to the upper right corner. Many magnetized filaments can be seen parallel to the bubbles. In this composite view, the sky to the left of the nearest second antenna is the night sky visible to the naked eye, and the right radio image has been enlarged to emphasize its fine features. Credit: Oxford, SARAO

An international team of astronomers has discovered one of the greatest features ever seen in the center of the Milky Way: a pair of huge radio-emitting bubbles that dominate for hundreds of years. light above and below the central region of our galaxy.

This hourglass-like feature, which surpasses all other radio structures in the galactic center, is probably the result of a phenomenal explosion of energy that erupted near the supermassive of the Milky Way. black hole a few million years ago.

"The center of our galaxy is relatively quiet compared to other galaxies with very active central black holes," said Ian Heywood of Oxford University and senior author of an article in the newspaper. Nature. "Nevertheless, the central black hole of the Milky Way can, from time to time, become unusually active, ignite by periodically devouring huge masses of dust and gas. It is possible that such binge eating triggered terrible explosions that inflated this unique feature. "

Using the MeerKAT telescope of the South African Radio Astronomy Observatory (SARAO), Heywood and his colleagues mapped vast areas in the center of the galaxy, making observations at long distances. wave close to 23 centimeters. Radio broadcasts of this type are generated by a process called synchrotron radiation, in which electrons traveling at a speed close to the speed of light interact with strong magnetic fields. This produces a characteristic radio signal that can be used to draw energy regions in space. This radio light easily penetrates dust clouds that block visible light from the center of the galaxy.

By examining the almost identical size and shape of the twin bubbles, the researchers believe they have found convincing evidence of the formation of these features from a violent eruption that, over a short period of time, has passed through the interstellar medium in opposite directions. .

"The shape and symmetry of what we have observed strongly suggests that an event of staggering power occurred a few million years ago very near the central black hole of our galaxy, "said William Cotton, astronomer at the National Radio Astronomy Observatory in Charlottesville, Virginia, co-author on the paper. "This eruption was probably caused by large amounts of interstellar gas falling into the black hole, or by a massive explosion of star formation that sent shockwaves into the galactic center. In fact, these swollen bubbles in hot ionized gas near the galactic center feed it and generate radio waves that we could possibly detect here on Earth. "

The environment surrounding the black hole in the center of our galaxy is very different from the one that exists elsewhere in the Milky Way and is a region of many mysteries. Among them are very long and narrow filaments that have not been found elsewhere and whose origin has not been solved since their discovery 35 years ago. The filaments appear as radio structures of several tens of light years and about a light year.

"The radio bubbles discovered by MeerKAT now shed light on the origin of the filaments," said Farhad Yusef-Zadeh of Northwestern University in Evanston, Illinois, and co-author of the newspaper. "Almost all the more than one hundred filaments are confined by radio bubbles."

The authors suggest that the close association of filaments with bubbles implies that the energy event that created the radio bubbles is also responsible for accelerating the electrons required for the production of the emission radio magnetized filaments.

"These huge bubbles were hitherto masked by the light of an extremely bright radio broadcast from the center of the galaxy," said Fernando Camilo of SARAO, Cape Town, co-author of the newspaper. "Teasing bubbles from the background noise was a technical feat, made possible only by the unique characteristics of MeerKAT and its ideal location," said Camilo. "With this unexpected discovery, we are witnessing the Milky Way to a new manifestation of flux of matter and energy on the scale of the galaxy, ultimately ruled by the central black hole.

According to the researchers, the discovery of these bubbles relatively close to the center of our galaxy of origin brings us even closer to the understanding of the spectacular activities that take place in more distant cousins ​​of the Milky Way through the world. ;universe.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under a cooperative agreement by Associated Universities, Inc.

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The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under a cooperative agreement by Associated Universities, Inc.

Reference: "Inflation of bipolar radio bubbles of 430 parsecs in the Galactic Center by an energy event", I. Heywood, et al., Nature.