Astronomers Find a Third Galaxy Missing Its Dark Matter

Astronomers have long argued that dark matter is the invisible scaffolding that holds galaxies together. Without its immense gravitational pull, the rotational spins of galaxies would force them to simply fly apart. But now, scientists have found a string of galaxies that seem to be missing their dark matter entirely. The latest in this string, known as NGC 1052-DF9, is described in a new paper, available in pre-print on arXiv, by Michael Keim, Pieter van Dokkum and their team from Yale. It lends credence to a radical theory of galaxy formation known as the “Bullet Dwarf” collision scenario, which has been a controversial idea for the last decade.