This inactive black hole has been discovered using gravitational lensing, a novel method that will help astronomers catalog more of its kind.

A team of astronomers from Durham University have discovered one of the largest black holes ever found, taking advantage of a phenomenon called gravitational lensing. The study has been published in the journal ‘Monthly Notices of the Royal Astronomical Society’.

The scientists used gravitational lensing to discover this hole. A galaxy in the foreground deflects light from a distant object and magnifies it, but computer simulations allowed the team to examine what that light was like deflected by a black hole.

The black hole, considered ultramassive, is located within a galaxy millions of light years from Earth. Its mass is more than 30,000 million times that of the Sun, being one of the largest ever discovered and the first using this technique. This is gravitational lensing that occurs when the gravitational field of a foreground galaxy appears to deflect light from a background galaxy, meaning we observe it more than once, explains the Royal Society for Astronomy.

Like a real lens, this effect also magnifies the background galaxy, so scientists can study it in greater detail. This is how astronomers distinguished this ultramassive and inactive black hole, one of the largest cataloged to date.

One of the study’s authors, James Nightingale, stated that “this particular black hole […] is one of the largest ever detected and is at the upper limit of how large we think black holes can theoretically become, for which is an extremely exciting discovery.”

Also, Nightingale explained that most of the black holes that are currently known are active, where the matter that approaches them is heated and released in the form of light or X-rays. “However, gravitational lensing makes it possible to study inactive black holes , something that is currently not possible in distant galaxies. This approach could allow us to detect many more black holes beyond our local universe and reveal how these exotic objects evolved further back in cosmic time.”

source: https://academic.oup.com/mnras/article/521/3/3298/7085506?login=false