More than two dozen missing “cocoons” black holes They have been rediscovered after researchers looked at the X-ray maps of the sky. All of these singularities had been wrongly classified as distant galaxies or other types of black holes.
The 28 objects are supermassive black holes, billions of times the mass of our sun. And they are all going through a stage of development where they wrap themselves in a dark bubble of dust and other materials. Those cocoons obscure the bright X-rays emitted by hot material that rotates around their event horizons, the point of no return for falling matter, making them appear dimmer than they really are. Black hole formation models suggest that there should be many black holes like this in the sky, but until now, scientists have not seen as many as expected. This new research, based on observations of a patch from the southern sky, suggests that many of them were hiding in plain sight.
“We like to say that we found these giant black holes, but they really were there the entire time,” Johns Hopkins astronomer Erini Lambrides, a doctoral student who led the study, he said in a statement from the Chandra X-ray Observatory.
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To distinguish these disguised black holes, the researchers compared Chandra Deep Field-South (CDF-S) X-ray images, an ultra-detailed X-ray image of a patch in the southern sky, with infrared and optical observations of the same patch. of heaven
Sixty-seven supermasses had already been found wrapped in the image. But the researchers found 28 objects that looked dim on the X-ray image but bright on infrared and optical wavelengths. They turned out to be black holes in the active centers of galaxies that had been so well hidden by their cocoons that they looked at the Chandra X-ray telescope as an older supermassive black hole or more distant galaxies.
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“More than 40% of our sample has underestimated intrinsic darkening,” the researchers wrote in an article published May 15 in the prepress database. arXiv And it will soon appear in The Astrophysical Journal, which means that 40% of the objects they studied turned out to be black holes with a certain level of cocoon that previous studies had not taken into account.
That’s a big problem for two reasons, they said.
First, the development of supermassive black holes is complex, and astrophysicists still don’t quite understand it. Objects are so large that it is difficult to explain how they acquired all their mass even billions of years to gobble up matter. There is simply not enough mass available and it takes time for any part of the mass to fall into a black hole.
These new data could improve theoretical models of how gigantic singularities form, revealing that black holes spend more time in that cocoon stage than previously thought. That could shed light on the history of large galaxies like the Milky Way with its giant central black holes.
The second reason has to do with the “X-ray background”.
X-ray observations of the sky reveal many different objects, but there is also a diffuse glare outside the X-ray energy range that Chandra, by far the most advanced X-ray telescope, can easily detect. Astronomers do not have a clear picture of this brightness. But many researchers suspect that invisible black holes are involved in their production.
The researchers wrote that a larger than expected population of cocooned black holes could help explain some of the less understood parts of that X-ray background.
Originally published in Live Science.
