Dark Matter Annihilation Must Be Very Rare If It Happens

Examination of the cosmic rays produced by a dwaft galaxy with an apparent high proportion of dark matter places strict limits on the dark matter annihilation cross-section and mean dark matter lifetime for dark matter candidates with 10 GeV or more of mass.

The age of the universe is about 4.35*10¹⁷ seconds (13.8 billion years). The minimum mean lifetime of dark matter with various assumptions given the observations made in this study is from 10²⁵ to 10²⁷ seconds.  Thus, 99.999999% or more of the dark matter, if it exists and has 10 GeV or heavier particles, that ever in existence during the lifetime of the universe must still exist.