Dark sector production and baryogenesis from not quite black holes
  Primordial black holes have been considered as an attractive dark matter
candidate, whereas some of the predictions heavily rely on the near-horizon
physics that remains to be tested experimentally. As a concrete alternative,
thermal 2-2-holes closely resemble black holes without event horizons. Being a
probable endpoint of gravitational collapse, they not only provide a resolution
to the information loss problem, but also naturally give rise to stable
remnants. Previously, we have considered primordial 2-2-hole remnants as dark
matter. Due to the strong constraints from a novel phenomenon associated with
remnant mergers, only small remnants with close to the Planck mass can
constitute all of dark matter. In this paper, we examine the scenario that the
majority of dark matter consists of particles produced by the evaporation of
primordial 2-2-holes, whereas the remnant contribution is secondary. The
products with light enough mass may contribute to the number of relativistic
degrees of freedom in the early universe, which we also calculate. Moreover,
2-2-hole evaporation can produce particles that are responsible for the baryon
asymmetry. We find that baryogenesis through direct B-violating decays or
through leptogenesis can both be realized. Overall, the viable parameter space
for the Planck remnant case is similar to primordial black holes with Planck
remnants. Heavier remnants, on the other hand, lead to different predictions,
and the viable parameter space remains large even when the remnant abundance is
small.
