Early dressing of primordial black holes with cold dark matter particles
Abstract: If primordial black holes make up a fraction of the cosmological dark matter, then they could in principle efficiently accrete other dark matter species soon after their collapse, at least from the time these other species can free stream in the early universe. Considering exotic thermal particles as the main dark matter component, I will show that the subsequent building up of very compact particle dark matter halos around black holes is a linear process in the radiation-domination epoch, which can be predicted almost fully analytically (a result first obtained by Eroshenko, which my colleagues and I have slightly corrected since then). This takes the form of scale invariant solutions describing compact dark matter halos with different profile indices that depend not only on the black hole and particle masses, but also on the kinetic decoupling time of the latter. All this may further translate into mutual exclusion limits if dark matter particles can self-annihilate, which has important consequences if one of these dark matter candidates happens to be discovered in future observations.
