Astronomers said Thursday they spotted a hot bubble of gas spinning clockwise around the black hole at the center of our galaxy at “breathtaking” speeds. The detection of the bubble, which survived only a few hours, should give some insight into the workings of these invisible and insatiable galactic monsters.
Thelurks in the middle of the Milky Way some 27,000 light-years from Earth, and its immense pull gives our home galaxy its characteristic whirlwind.
The very first image of Sagittarius A* was revealed in May by the Event Horizon Telescope Collaboration, which links satellite dishes around the world aiming to detect light as it disappears into the maws of black holes.
One such dish, the ALMA radio telescope in the Chilean Andes, detected something “really puzzling” in the data from Sagittarius A*, said Maciek Wielgus, an astrophysicist at the Max Planck Institute for Radio Astronomy in Germany.
Minutes before ALMA’s radio data collection began, the Chandra space telescope observed a “huge spike” in X-rays, Wielgus told AFP.
This burst of energy, thought to be similar to solar flares on the sun, sent a bubble of hot gas swirling around the black hole, according to a new study published in the journal Astronomy and Astrophysics.
The gas bubble, also known as the hotspot, had an orbit similar to Mercury’s journey around the sun, said the study’s lead author Wielgus.
But while it takes Mercury 88 days to make this trip, the bubble did it in just 70 minutes. This means it traveled at about 30% of the speed of light.
“So it’s an absolutely, ridiculously fast spinning bubble,” Wielgus said, calling it “mind-blowing.”
The scientists were able to follow the bubble through their data for around an hour and a half – it was unlikely to have survived more than two orbits before being destroyed.
Wielgus said the sighting supported a theory known as MAD. “MAD like crazy, but also MAD like magnetically stopped records,” he said.
The phenomenon is thought to occur when there is such a strong magnetic field at the mouth of a black hole that it prevents matter from being sucked into it.
But matter continues to build up, creating a “flux flare”, Wielgus said, which breaks up magnetic fields and causes a burst of energy.
By learning how these magnetic fields work, scientists hope to build a model of the forces that control black holes, which remain shrouded in mystery.
Magnetic fields could also help indicate the rotational speed of black holes, which could be of particular interest for Sagittarius A*.
While Sagittarius A* is four million times the mass of our sun, it only shines with the power of about 100 suns, “which is extremely unimpressive for a supermassive black hole,” Wielgus said.
“It’s the faintest supermassive black hole we’ve seen in the universe – we only saw it because it’s very close to us.”
But it’s probably a good thing that our galaxy has a “hungry black hole” at its center, Wielgus said.
“To live next to a quasar”, which can shine with the power of billions of suns, “would be a terrible thing”, he added.
By definition, black holes cannot be directly observed because nothing, not even light, can escape the overwhelming inner force of their titanic gravity.
But their presence can be indirectly detected by observing the effects of this gravity on the trajectories of nearby stars and by the radiation emitted across the electromagnetic spectrum by material heated to extreme temperatures as it is sucked into an “accretion disk”. ” in rapid rotation, then in the hole itself.
One of the main goals of the new James Webb Space Telescope is to help astronomers map the formation and growth of these black holes in the wake of the Big Bang.
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