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We tend to think of supermassive black holes as relatively stationary things – sitting there in the middle of a galaxy while everything else swirls around it.
But that’s not always the case, and astronomers now have the best evidence of a supermassive black hole that not only moves through the Universe, but moves in its own galaxy. He’s got ants in his pants and witches in his panties, and while it’s unclear why, the possible explanations are really exciting.
“We don’t expect the majority of supermassive black holes to move; they usually just sit there, ”said astronomer Dominic Pesce of the Harvard & Smithsonian Center for Astrophysics.
“They’re so heavy that it’s hard to get them started. Consider how harder it is to throw a bowling ball in motion than it is to hit a soccer ball – knowing that in this case the ‘bowling ball “is several million times the mass of our Sun. It’s going to take a pretty powerful kick.”
Catching a peripatetic supermassive black hole is no small feat. They can only be found in vast gulfs of space, millions to billions of light years away; at these distances, isolating the movement of an object – even if that object is a supermassive black hole – in an entire galaxy is a challenge.
Pesce and his team figured they might get lucky with a type of galactic nucleus called a megamaser. It is a type of active supermassive black hole with an accreting disk of gas and dust injected into it, generating large amounts of heat and light.
With a megamaser, there is an additional ingredient to this formula: molecules such as hydroxyl, water, formaldehyde, and methine that boost the brightness of the nucleus in microwave wavelengths.
Using a technique called Super Long Base Interferometry, which combines observations from an array of radio telescope antennas to effectively create a huge observation dish, the speeds of these megamasers can be measured very precisely.
By studying water megamasers in particular, Pesce and his colleagues hoped to be able to identify supermassive black holes moving at a different speed than the galaxy around them.
“We asked: Are the speeds of black holes the same as the speeds of the galaxies in which they reside?” he said. “We expect them to have the same speed. Otherwise, it means the black hole has been disturbed.”
The team took a close look at 10 megamasers, comparing black hole velocity data to observations of the entire galaxy. Sure enough, nine of them met our expectations of supermassive black holes hidden in the galactic center, like a spider in a web.
One of them, however, showed different behavior. The spiral galaxy J0437 + 2456, located about 228 million light-years away, has a supermassive black hole about 3 million times the mass of the Sun, which appeared to be moving at a significantly different speed than the rest of the galaxy.
According to the team’s analysis, the speed of the supermassive black hole is around 4,810 kilometers per second (2,990 miles per second). The galaxy’s neutral hydrogen, on the other hand, appears to be receding at a speed of 4,910 kilometers per second. According to observations of the movements of stars and gas, the speed of the inner region of the galaxy is 4,860 kilometers per second.
Because all of these metrics differ quite significantly from each other, and the whole galaxy’s velocity structure looks pretty complicated, it’s hard to say exactly why everything is teetering in there.
There are several possible explanations. The galaxy might be in the process of encountering another massive object, such as another galaxy. The supermassive black hole could have collided with another supermassive black hole, generating a recoil kick that pushed the black hole out of position; the flicker could be the galaxy and the black hole recovering.
Or the black hole could have an invisible binary companion, the two objects orbiting a mutual center of gravity in the galactic core.
“Despite all the expectations that they really should be out there in some abundance, scientists have struggled to identify clear examples of binary supermassive black holes,” Pesce said.
“What we might see in the galaxy J0437 + 2456 is one such pair of black holes, the other remaining hidden from our radio observations due to its lack of maser emission.”
Whether it’s a recoil kick or a binary companion, that would be amazing news for astrophysics. There are a lot of unanswered questions about supermassive black holes, like how do they get so big and whether supermassive black hole binaries can close the final parsec of the distance between them. Supermassive black hole binary and fusion evidence could help answer these questions.
This is also great news for us here in the Milky Way: as we are a few billion years away from a galactic merger, there is very little chance that our supermassive black hole, Sagittarius A *, will develop any time soon. the desire to travel.
The team hopes to make more observations of the galaxy and its particular nucleus in an attempt to narrow down the cause of its strange behavior.
The research was published in The astrophysical journal.
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