Narrator (April Hobart, CXC): Since the 1980s, astronomers have known about a mysterious class of objects that they call "ultraluminous X-ray sources," or ULXs. They named them this because these objects give off more X-ray light than most other binary systems where black holes or neutron stars are in orbit around a normal companion star. Recently, scientists using NASA's Chandra X-ray Observatory and optical telescopes spotted a ULX in the spiral galaxy M83 that was acting even more strangely. This ULX increased its output in X-rays by 3,000 times over the course of several years. Using clues found in the X-ray and optical data, researchers think this ULX may be a member of a population of black holes that up until now was suspected to exist but had not been confirmed. These black holes, which are the smaller stellar-mass black holes, are older and more volatile than previously thought.
Revised: May 19, 2022