Tweak to dark matter may explain Milky Way mystery
Radiation in early universe might illuminate problem of missing satellite galaxies
BLINDED BY THE LIGHT Dark matter envelops a galaxy similar in size to the Milky Way in this computer simulation, where red indicates high densities of dark matter and blue shows low densities. On the left, traditional dark matter creates many satellite galaxies. At right, dark matter that interacts with light produces far fewer.