Researchers have discovered eight new “echo” black hole systems in the Milky Way, and they sound like they’re going through a terrifying wind tunnel. Interestingly, the echoes point to the role of black holes in the evolution of galaxies.

A little about black holes

The gravitational force of a black hole is so great that even light cannot leave it. Black holes are often surrounded by superheated accumulations of gas and dust known as accretion disks. When a black hole is “fed” by this material, it produces bright flashes of X-ray light reflected from the gas falling on it.

In a new study, researchers at the Massachusetts Institute of Technology (MIT) used a tool called the Reverberation Machine to identify eight new eco-double black holes, or systems with a star orbiting a black hole.

what scientists found

BEAUTIFUL It studies X-rays from sources such as black holes and neutron stars.

Using this data, the team’s algorithm identified 26 X-ray double black holes known to emit X-ray flares. The team then narrowed down the list to 10 systems that were close and bright enough for researchers to distinguish between the X-ray echoes between the flashes.

This method detected eight previously unknown echoes from neighboring X-ray double black holes. According to the Massachusetts Institute of Technology, only two such systems are known to emit X-rays in the Milky Way.

The researchers found that among the eight systems identified, black holes have a mass of between 5 and 15 solar masses, and all of them are “fed” by sun-like stars. Using this data, the team recreated the evolution of a black hole as it “eats” stellar material and then converted the X-ray echo into sound waves that you can listen to.

How black holes swallowing stars sound: video

Scientists reproduce black hole evolution

By comparing the echo signals from the eight systems, the researchers found a general evolution in the immediate vicinity of black holes.

Black holes produce X-rays for several weeks. At this time, glowing crowns are appearing around black holes – regions of high-energy plasma just outside the black hole – and jets of matter moving at nearly the speed of light. Then, within a few days, the peaks begin to fade and the jets evaporate as the black holes transition to a lower energy state.

However, black holes emit a final burst of high-energy particles before they are completely destroyed. According to scientists, this could help explain how supermassive black holes, believed to be at the center of all large galaxies, affect the formation of galaxies by emitting particles over great distances.

The role of black holes in the evolution of galaxies is an unresolved issue in modern astrophysics. Interestingly, these double black holes look like “mini” supermassive black holes, and so by understanding flares in these small, nearby systems, we can understand how similar flares in supermassive black holes affect the galaxies they’re in.
— said Erin Kara, co-author of the study and associate professor of physics at the Massachusetts Institute of Technology.

Some of the X-rays are reflected from the black hole’s accretion disks, creating an echo of the initial radiation. The researchers calculated the distance between the black hole corona and the accretion disk based on when NICER received light from the apex, not when it detected X-rays. In turn, the map around the black hole provided clues as to how its crown and disk evolved.

In addition, the researchers found that the transition time from the high-energy state to the low-energy state increased in all double black holes studied, suggesting that the distance between the crown and the disk also increased. This could be the result of the corona’s short-term expansion “before the stellar meal completed and subsided” during the most recent high-energy black hole explosion, the researchers said.