Astronomers observed the fleeting appearance of a bubble of gas circulating at speedsmind-bogglingaround the black hole at the center of our galaxy, according to a scientific study published this Thursday, September 22. 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.
A signal “very surprising»
ALMA, one of these radio telescopes located in Chile, picked up a signalvery surprisingin the observation data of Sagittarius A*, explained to AFP the astrophysicist Maciek Wielgus, of the German Max Planck Institute for Radio Astronomy.
Minutes before ALMA collected this data, the Chandra Space Telescope detected “a huge showof X-rays from Sagittarius A*, he explained. 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.
Speed that “defies the imagination”
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 thatdefies the imagination“, according to Maciek Wielgus. 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 matter leads to a “stream rash“, 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 spin on themselves.
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