Dormant Black Hole Found Outside the Galaxy

A team of international scientists, including researchers from the renowned UK institution, the University of Sheffield, discovered a stellar-mass black hole in a neighboring galaxy.

The team discovered that the star that gave rise to the black hole vanished without leaving any trace of a supernova explosion. Six years of observations with the European Southern Observatory's (ESO) Very Large Telescope resulted in the discovery (VLT).

When massive stars reach the end of their lives and collapse under their own gravity, stellar-mass black holes form. This process leaves a black hole in orbit with a luminous companion star in a binary, a system of two stars revolving around each other. If a black hole does not emit high levels of X-ray radiation, which is how such black holes are typically detected, it is said to be 'dormant.'
Dormant black holes are particularly difficult to detect because they have little interaction with their surroundings. The team has been looking for black-hole-binary systems for more than two years, and they are especially excited about the discovery, dubbed VFTS243, which they believe is the most convincing candidate reported to date.

Professor Paul Crowther, Head of the Department of Physics and Astronomy, and Professor of Astrophysics at the University of Sheffield says “It’s a very exciting discovery. Although a number of `dormant’ black hole candidates have been proposed, this is the first to be unambiguously detected outside our galaxy.”