Bounds on warm dark matter from Schwarzschild primordial black holes

We consider light dark matter candidates originated from the evaporation of Schwarzschild primordial black holes, with masses in the range 10(-5)-10(9) g. These candidates are beyond standard model particles with negligible couplings to the other particles, so that they interact only gravitationally. Belonging to the category of warm dark matter, they nevertheless spoil structure formation, with a softer impact for increasing values of the candidate spin. Requiring such candidates to fully account for the observed dark matter, we find that the scenario of black hole domination is ruled out for all spin values up to 2. For the scenario of radiation domination, we derive upper limits on the parameter beta (the primordial black hole energy density at formation over the radiation one), which are less stringent the higher the candidate spin is.

Automated summary

Light dark matter candidates from evaporating Schwarzschild primordial black holes with negligible couplings to other particles are considered, belonging to warm dark matter but potentially spoiling structure formation, ruling out black hole domination for all spin values up to 2, and deriving less stringent upper limits on the parameter beta for radiation domination with higher candidate spin values.