Chandra X‐Ray Observatory Examines a New Kind of Black Hole

For decades, astronomers have been accumulating increasingly strong evidence for the existence of black holes in two distinct mass regimes: “stellar” black holes, weighing a few times the mass of the Sun $(M⊙),$ and “supermassive” black holes with masses ranging from $106−109M⊙,$ always sitting at the centers of galaxies. There seemed to be nothing in between.