The Universe is full of galaxy tablets, but Abell 2261 is in its own class. In the galaxy in the center of the cluster, where one of the largest black holes should be in the Universe, astronomers have not been able to find such a thing.
And a new study has just made the absence more interesting: if the supermassive black hole went out into space, there should be evidence left about it. But there is no trace of it in the material around the galactic center, either.
But this means that restrictions can be placed on what the supermassive black hole – if it exists, avoids detection – does.
Galaxy collections are the most recognizable structures in the universe. They are usually groups of hundreds to thousands of galaxies that are interconnected, with one large, bright galaxy at or closing the center, known as the lightest clustered galaxy (BCG).
But even among BCGs, BCG Abell 2261 (pronounced, of course, A2261-BCG, and located about 2.7 billion light-years away) stands out. It is about a million light-years across – up to 10 times the size of a Milky Way galaxy – and has a light, puffy heart of 10,000 light-years across, the largest galactic heart ever seen.
Which one could it be ??? (NASA; ESA; M. Postman, STScI; T. Lauer, NOAO, Tucson; CLASH team)
Based on the mass of the galaxy, which is related to the size of a black hole, an animal should have a total black hole at its heart, between 3 and 100 billion times the mass of the sun, which could be one of the largest known black holes (the Milky Way’s supermassive black hole is 4 million solar masses).
But instead of absorbing the radiation you would expect from an active black hole as it churns and heats the material around it, the A2261-BCG core is filled with a diffused mist of light. clear. Various instruments, including the Chandra X-ray Observatory, the Large Array and the Hubble Space Telescope, have failed to detect a black hole in the center of A2261-BCG.
Now a team of astronauts led by Kayhan Gultekin of the University of Michigan at Ann Arbor has gone back to Chandra for a deeper set of ideas, based on the idea that the horrible black hole was kicked out .
It’s not that wild. BCGs are expected to grow when combined with other diseases. When this happens, the black holes at the center of these unified galaxies would come together, slowly spinning towards each other before coming together to form one larger black hole.
We know, now, from astronomy of gravitational waves, proud black holes converge sending gravitational waves spanning space-time. It is possible that, if the gravitational waves were stronger in one direction, the gravity retraction could kick the unified black hole in the other side.
It would be surprising to find evidence of this. First, the rediscovery of a black hole union has not yet been discovered, which means it is still hypothetical. But we also don’t know if horrible black holes can come together.
According to numerical simulations of horrific black hole unions, they can not. That’s because as their orbit declines, and also the area of space where they can transfer energy. By the time the black holes are one parsec apart (about 3.2 light-years), theoretically this area of space is no longer large enough to support orbital decay, so they will be in stable binary orbit, probably for billions of years. This is the last parsec problem.
There have been a number of advertisements indicating that such a merger may have taken place at the heart of A2261-BCG. It’s the size of a heart, to begin with. In 2012, scientists suggested that two black holes fused out could form a cluster of stars from the heart, building up the area. This would also explain why the dense density of 2,000 light-years from the heart.
In 2017, scientists looked for a high density of stars that would be trapped in the gravity of something as large as the unified black hole as it erupted from the galactic center. Of the three groups, two were rejected and the third was inconclusive.
(NASA / CXC, NASA / STScI, NAOJ / Subaru, NSF / NRAO / VLA)
So Gultekin and his team used Chandra to take a closer look at the A2261-BCG core, and combined it with archival data to detect a low level of horrible black hole activity. Radio broadcasts had previously shown that the last black eclipse activity occurred at the center of the galaxy around 48 million years ago, so the team was very careful to explore that area as well.
They also looked at stellar densities around the galactic core.
What the team found is that the density of the hot gas decreases as it approaches the plant; so the highest gas density is not in the center of the heart, but around it. But none of the sites they studied showed any evidence of the X-radiation related to black hole activity.
Since black holes do not emit recognizable radiation on their own, and we can usually only detect them when eating, it is possible that there is a black hole in the middle of A2261-BCG. If so, it is either questionable, or a case of slow accretion to be determined by our standard instruments.
The other explanation is that the black hole has been kicked in much longer than we have been looking at. More sensitive instruments in the future may help answer this interesting question.
The research was approved by AAS Journals, and is available on arXiv.