The case for co-decaying dark matter
Monday, December 5, 2016 - 09:31
in Astronomy & Space
(Phys.org)—There isn't as much dark matter around today as there used to be. According to one of the most popular models of dark matter, the universe contained much more dark matter early on when the temperature was hotter. As the universe cooled, the dark matter annihilated away, at least up until a point when thermal equilibrium was reached and the annihilations ceased, resulting in the number of dark matter particles in the universe "freezing out" and remaining roughly constant.