The Mystery of Ultra-Luminous X-ray Sources
Does the existence of mysterious, ultra-luminous X-ray sources indicate that black holes may become more massive than previously thought?
Ultra-Luminous X-ray Sources and Intermediate Mass Black Holes: A lost middle sibling in the black hole family tree?
Continuums seem to be the name of the game in astronomy. On more than one occasion, astronomers have defined discrete subclasses for a type of phenomena only to later discover objects which populate an intermediate space between their original classifications. So… what about black holes?