Hubble uncovers concentration of small black holes

Scientists were expecting to find an intermediate-mass black hole at the heart of the globular cluster NGC 6397, but instead they found evidence of a concentration of smaller black holes lurking there. New data from the NASA/ESA Hubble Space Telescope have led to the first measurement of the extent of a collection of black holes in a core-collapsed globular cluster.

source https://www.sciencedaily.com/releases/2021/02/210211144331.htm