Solar Mass Primordial Black Holes in Moduli Dominated Universe
  We explore the prospect of producing primordial black holes around the solar
mass region during an early matter domination epoch. The early matter-dominated
epoch can arise when a moduli field comes to dominate the energy density of the
Universe prior to big bang nucleosynthesis. The absence of radiation pressure
during a matter-dominated epoch enhances primordial black hole formation from
the gravitational collapse of primordial density fluctuations. In particular,
we find that primordial black holes are produced in the $0.1-10~M_{\odot}$ mass
range with a favorable choice of parameters in the theory. However, they cannot
explain all of the merger events detected by the LIGO/Virgo gravitational wave
search. In such a case, primordial black holes form about $4\%$ of the total
dark matter abundance, of which $95\%$ belongs to the LIGO/Virgo consistent
mass range. The rest of the dark matter could be in the form of particles that
are produced from the decay of the moduli field during reheating.
