Astronomers are involved hunting for a missing space creature. The quarry in question is dark, relentless and roughly approaching 100 billion times the mass of the Sun..
For years, scientists have observed a large galaxy 2.7 billion light-years from Earth. From every piece of data they have collected, there is clear evidence to suggest that a massive black hole is hiding at the center of the galaxy, much like in our own Milky Way. But while scientists are determined that the black hole is there, they have failed to find it. No sign.
But they are getting closer to solving this great mystery. Using a new set of data, a team of researchers was able to access the potential abode of the missing black hole, allowing them to create several scenarios to explain where this giant might be hiding.
Kayhan Gultekin, a professor in the Department of Astronomy at the University of Michigan, is the lead author of a new study detailing these scenarios. Says Inverse he is absolutely sure it is a black hole is there – and he is determined to find it.
“It’s there, it’s just very hard to find,” Gultekin says.
The work of Gultekin and his colleagues is described in detail in a study published on a network overprint server arXiv. Although not peer-reviewed, the study was accepted for publication in the journals of the American Astronomical Society.
The mystery began in 1999 – Using NASA’s X-ray Observatory Chandra, astronomers have collected observations on a cluster of galaxies called Abell 2261. At the center of the cluster is a galaxy that overpowers the rest: Abell 2261-BCG. This galaxy is about ten times larger than our Milky Way.
It is well established that galaxies the same size as the Milky Way or larger contain a massive black hole at their center. The supermassive black hole at the center of the Milky Way is 3.6 million times larger than the mass of the Sun.
But the observations of Abella 2261-BCG it is not discover a black hole in the center of a large galaxy.
Astronomers conducted additional observations using NASA’s Chandra in 2004, and later collected images of the galaxy with NASA’s Hubble Space Telescope and Subaru’s telescope, as well as measurements of radio emissions using a very large-scale telescope by Karl G. Jansky of the National Science Foundation. .
And yet: There are still no black holes.
Astronomers were not restrained. In 2018, scientists once again tried Chandra, recording further X-ray observations of the galaxy. By imaging an entire cluster of galaxies surrounding Abell 2261-BCG, they were able to look deeper into the black hole than ever before.
It is technically difficult to find all the black holes because they are dark – light cannot escape from their depth.
Astronomers typically locate black holes from the movement of stars next to them or when they spy on certain bright sparks from black holes formed from materials they pull toward them, forming a strip of dust, gas, and other objects known as their accretion disk.
But some of these cosmic beasts can be shy and quiet despite their size, which may be the case with this missing black hole, Gultekin says.
In a new study, he and his colleagues narrowed this mystery down to two powerful possible explanations:
The first scenario suggests that the black hole at the center of the galaxy does not swallow much material from its surroundings, and therefore does not accumulate as much matter.
“So we can’t see the control signs of matter secretion,” Gultekin says. “If it was really bright, it would be easy.”
Another scenario is pretty out there, literally.
Researchers suggest the black hole may have been expelled from a galaxy after its host merged with another galaxy. The two black holes of the galaxies in question would merge, creating a binary black hole.
As the two black holes merge, they release a strong ripple through space and time known as the gravitational wave. The momentum created by the gravitational waves would be strong enough to completely eject the original black hole from the galaxy.
This process is known as indentation of a black hole. Astronomers have theorized these black holes before, but have never noticed it.
If ejected from Abella 2261-BCG, the missing black hole may be floating aimlessly through space, perhaps surrounded by several stars.
If this is the case, then the missing black hole is basically impossible to find. That will remain a mystery to us forever.
Summary: We use Chandra X-ray observations to look for evidence of a black hole retreating from the brightest cluster galaxy in Abell 2261 (A2261-BCG). The A2261-BCG is a strong candidate for black hole retraction due to its large, flat stellar core, discovered by observing the Hubble Space Telescope. With Chandra, we took 100 ksec observations and combined them with 35 ksex archival observations to look for a low-level increment on a black hole of expected mass M∼1010 M⊙ that could be located in one of four star nodes off-center near the center of the galaxy, or at the optical center of the galaxy or at the location of a radio show. We did not find any X-ray emission from a point source that exceeds the cluster gas and we can set limits to the accumulation of any black hole in the central region at a flux of 2-7 keV below 4.3 × 10−16 erg s – 1 cm – 2, which corresponds to a bolometric Eddington fraction of about 10−6. Therefore, there is no 1010 M⊙ black hole in the A2261-BCG core or it is accreted at a low level. We also discuss the morphology of the X-ray emitting gas in the cluster and how its asymmetry is consistent with a large dynamic event.