Astronomers have observed a bubble of gas circulating very quickly in the center of our galaxy

This observation could help to understand the behavior of black holes. The phenomenon would be of magnetic origin, according to the authors of the study which reveals the detection of this bubble.

Astronomers have observed the fleeting appearance of a bubble of gas circulating at “amazing” speeds around the black hole at the center of our galaxy, according to a scientific study published Thursday.

The detection of this bubble, whose lifetime did not exceed a few hours, could provide information on the behavior of black holes. These astronomical objects are all the more mysterious in that they are literally invisible, their gravitational force being such that not even light can escape.

Sagittarius A*, the supermassive black hole lurking at the heart of the Milky Way, is about 27,000 light-years from Earth. It was detected thanks to the movement of stars orbiting around it. The EHT collaboration, a worldwide network of radio-telescopes, published last May the first image of the ring of material that surrounds the black hole before being absorbed into it.

The image of a supermassive black hole at the heart of our galaxy, released on May 12, 2022.
The image of a supermassive black hole at the heart of our galaxy, released on May 12, 2022. © EHT COLLABORATION

A “very surprising” signal

ALMA, one of these radio-telescopes which is located in Chile, has picked up a “very surprising” signal in the observation data of Sagittarius A *, explained to AFP the astrophysicist Maciek Wielgus, of the German Institute Max Planck for Radio Astronomy.

A few minutes before ALMA collected this data, the Chandra space telescope detected “a huge emission” of X-rays from Sagittarius A *, he detailed.

This burst of energy, believed to be similar to solar storms from the Sun, sent a bubble of gas flying around the black hole at full speed, according to the study published in the journal Astronomy and Astrophysics.

The phenomenon observed for about an hour and a half made it possible to calculate that the gas bubble made a complete orbit of the black hole in just 70 minutes, and therefore at a speed equivalent to 30% of that of light, which goes to 300,000 km per second. A speed that “defies the imagination”, according to Maciek Wielgus.

A phenomenon of magnetic origin

The phenomenon would be of magnetic origin, according to a theory exposed by the scientist. The black hole’s magnetic field is so powerful that it prevents some of the matter circulating around it from being absorbed into it.

But this accumulation of material leads to a “flux eruption”, which makes a breach in the magnetic field and releases a burst of energy, in the form of a bubble of gas, according to the astrophysicist.

Observations of these magnetic fields should help understand how black holes work. They could also indicate how fast these black holes rotate on themselves.

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