Solar Mass Primordial Black Holes in Moduli Dominated Universe

TL;DR

This paper investigates the formation of solar mass primordial black holes during an early matter-dominated epoch driven by moduli fields, highlighting their potential contribution to dark matter and implications for gravitational wave observations.

Contribution

It demonstrates that primordial black holes in the 0.1-10 solar mass range can form during a moduli-driven matter epoch, with specific parameter choices, and assesses their role in dark matter and gravitational wave events.

Findings

Primordial black holes in 0.1-10 M_sun range can form during moduli-dominated epoch.

These black holes constitute about 4% of dark matter, mostly in the LIGO/Virgo mass range.

They cannot account for all LIGO/Virgo merger events.

Abstract

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.