A spectacular set of rings around a black hole has been captured using NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory.
The X-ray images of the giant rings have revealed new information about dust located in our Galaxy, using a similar principle to the X-rays performed in doctor’s offices and airports.
The black hole is part of a binary system called V404 Cygni, located about 7,800 light years away from Earth.
The black hole is actively pulling material away from a companion star — with about half the mass of the Sun — into a disk around the invisible object. This material glows in X-rays, so astronomers refer to these systems as “X-ray binaries.”
“The rings tell astronomers not only about the black hole’s behavior, but also about the landscape between V404 Cygni and Earth,” researchers at the Chandra X-ray Observatory wrote in a statement.
For example, the diameter of the rings in X-rays reveals the distances to the intervening dust clouds the light ricocheted off. If the cloud is closer to Earth, the ring appears to be larger and vice versa.
The light echoes appear as narrow rings rather than wide rings or haloes because the X-ray burst lasted only a relatively short period of time.
The rings are created by echoes of light, similar to what happens on Earth when sound waves bounce off solid surfaces.
“Instead of sound waves bouncing off a canyon wall, the light echoes around V404 Cygni were produced when a burst of X-rays from the black hole system bounced off of dust clouds between V404 Cygni and Earth. ” the statement added.
Cosmic dust is not like household dust but is more like smoke, and consists of tiny, solid particles.
The statement indicated that the rings are useful for scientists in understanding the black hole in more detail, as well as the distance between V404 Cygni and Earth.
The X-ray burst from the star system was first detected in June 2015, but the images were only recently released.
The composite image is a combination of X-rays seen by Chandra and data from the Pan-STARRS telescope in Hawaii that shows stars in the field of view.
The team analyzed 50 Swift observations made in 2015 between June 30 and August 25. Chandra observed the system on July 11 and 25. It was such a bright event that the operators of Chandra purposely placed V404 Cygni in between the detectors so that another bright burst would not damage the instrument.
The Swift Observatory was launched into space 17 years ago, and the Chandra X-ray Observatory was launched into space on July 23, 1999.
Sources:
- https://www.nasa.gov/mission_pages/chandra/images/huge-rings-around-a-black-hole.html
- https://chandra.si.edu/photo/2021/v404cyg/