WHICH came first, the galaxy or the black hole? That question has been
puzzling astronomers ever since they discovered that most galaxies have a
monster black hole at their core.
Now observations of one such black-hearted galaxy suggest that the galaxy
came first. Black holes formed later from individual stars in tight-knit
clusters, which merged to make a “middleweight” black hole that migrated to the
galactic centre.
Astronomers have long wanted to explain the size gap between small black
holes—up to 100 times the mass of the Sun—and supermassive ones that
are millions of times as massive. The…
