Astronomers discover three distinct groups of merging black holes
Black hole collisions do not appear to come from one simple cosmic recipe. After studying more than 150 mergers detected through gravitational waves, astronomers say the growing catalog points instead to three distinct groups of merging black holes. Each group seems to carry its own signature in mass, spin, and how often the mergers happened across cosmic time. Taken together, the pattern suggests that these violent collisions are being built in more than one kind of environment. Their analysis focuses on the fourth gravitational-wave transient catalog from the LIGO-Virgo-KAGRA Collaboration, known as GWTC-4. That catalog includes more than 150 detected black hole mergers, enough for researchers to stop treating these events as a single blended population and start asking whether different families are hiding inside the data. Artist’s impression of a pair of black holes merging, involving one with unusual spin. (CREDIT: Carl Knox, OzGrav, Swinburne University of Technology) Not one family, but three One clue came from the masses. When the researchers looked across the full sample, they did not see a smooth spread. …
