“X-ray magnifier” improves sight of distant black holes

By taking advantage of a natural lens in space, astronomers have captured an unprecedented look at x-rays from a black hole system in the early universe.

This magnifier was first used to refine X-ray images using NASA’s Chandra X-ray Observatory. He captured details of black holes that would normally be too far away to be studied using existing x-ray telescopes.

Astronomers have applied a phenomenon known as the “gravitational lens” which occurs when the path of light from distant objects is bent by a large concentration of mass, such as a galaxy, which lies along line of sight. This lens can magnify and amplify light in large quantities and create duplicate images of the same object. The configuration of these duplicate images can be used to decipher the complexity of the object and refine the images.

The gravitational lens system in the new study is called MG B2016 + 112. The X-rays detected by Chandra were emitted by this system when the universe was only 2 billion years old, compared to its current age of almost 14 billion years.

“Our efforts to see and understand objects so far away in x-rays would be doomed if we didn’t have a natural magnifying glass like this,” said Dan Schwartz of the Center for Astrophysics, Harvard & Smithsonian (CfA ), who led the study.

The latest research builds on previous work led by co-author Cristiana Spingola, currently at the Italian National Institute of Astrophysics (INAF) in Bologna, Italy. Using radio observations from MG B2016 + 112, his team found evidence of a pair of fast-growing supermassive black holes separated by only about 650 light-years. They discovered that the two black hole candidates may have jets.

Using a gravitational lens model based on the radio data, Schwartz and his colleagues concluded that the three x-ray sources they detected from the MG B2016 + 112 system must have resulted from the lens of two separate objects. These two x-ray emitting objects are probably a pair of growing supermassive black holes or a growing supermassive black hole and its jet. The estimated separation of these two objects is consistent with the radio work.

Chandra’s previous measurements of pairs or trios of growing supermassive black holes have typically involved objects much closer to Earth, or with much larger separations between objects. An X-ray jet at an even greater distance from Earth has already been observed, with light emitted when the universe was only 7% of its current age. However, the jet’s emission is separated from the black hole by about 160,000 light years.

This result is important because it provides crucial information on the rate of growth of black holes in the early universe and the detection of a possible double black hole system. The gravitational lens amplifies the light from those distant objects that would otherwise be too faint to be detected. X-ray light detected by any of the MG B2016 + 112’s objects can be up to 300 times brighter than it would have been without the lens.

“Astronomers have discovered black holes whose mass is billions of times greater than that of our Sun and which formed only a few hundred million years after the big bang, when the universe had only a few percent of his current age, “said Spingola. “We want to solve the mystery of how these supermassive black holes have grown in mass so quickly.”

Pulses from the gravitational lens can allow researchers to estimate how many systems containing two supermassive black holes have separations small enough to produce gravitational waves observable in the future with space detectors.

“In many ways, this result is an exciting proof of concept of how this ‘magnifying glass’ can help us reveal the physics of distant supermassive black holes in a new approach. Without this effect, Chandra should have observed a few. -a hundred times longer and even then wouldn’t reveal the complex structures, ”said co-author Anna Barnacka of CfA and Jagiellonian University, who developed the techniques to turn gravitational lenses into high-resolution telescopes to refine images.

“Thanks to the gravitational lens, much longer Chandra observations may be able to distinguish between the pair of black holes and the black hole and jet explanations. Will be online soon will provide tens of thousands of targets.” , concluded Schwartz.

The uncertainty in the x-ray position of one of the objects in MG B2016 + 112 is 130 light years in one dimension and 2000 light years in the other perpendicular dimension. This means that the size of the area where the source is probably located is more than 100 times smaller than the corresponding area for a typical Chandra source without a lens. Such precision in a position determination is unprecedented in X-ray astronomy for a source at this distance.

An article describing these results appears in the August issue of The Journal of Astrophysics.