The Dark Secret of Galaxies May Not be so Dark After All
Since the discovery of dark matter, most astronomers have concluded that every galaxy held some of its mass in the form of this enigmatic — something. Now, a pair of studies show that some galaxies do not hold onto any dark matter at all.
NGC 1052-DF2, found in 2015, is the first galaxy ever seen to contain little to no dark matter. This ultra-diffuse galaxy, which only loosely holds on to its member stars, was discovered by a team including Yale University graduate student Shany Danieli.
“The fact that we’re seeing something that’s just completely new is what’s so fascinating. No one knew that such galaxies existed, and the best thing in the world for an astronomy student is to discover an object, whether it’s a planet, a star, or a galaxy, that no one knew about or even thought about,” said Pieter van Dokkum of Yale University.
The mysteries of dark matter are immense. Whatever it is, this — something — is invisible, gives off no radiation, and only seems to interact with normal matter through the force of gravity. Yet, it holds galaxies together, and greatly “outweighs” normal matter throughout the visible Universe.
Playing Hide and Seek with Dark Matter
Evidence for dark matter between galaxies was first discovered in 1933 by astronomer Fritz…
