This image shows a standard prediction for the dark matter distribution within about 1 million light years of the Milky Way galaxy. Image credit: Garrison-Kimmel, Bullock (UCI)
This image shows a standard prediction for the dark matter distribution within about 1 million light years of the Milky Way galaxy, which is expected to be swarming with thousands of small dark matter clumps called `halos’. The scale of this image is such that the disk of the Milky Way would reside within the white region at the center. Until now, there was no observational evidence that dark matter actually clumps this way, raising concerns that our understanding of the cosmos was flawed in a fundamental way. Observations of the ultra-faint galaxy Segue 2 (zoomed image) have revealed that it must reside within such a tiny dark matter halo, providing possibly the first observational evidence that dark matter is as clumpy as long predicted. Image credit: Garrison-Kimmel, Bullock (UCI)