Stellar mass Primordial Black Holes as Cold Dark Matter

TL;DR

This paper investigates the formation of stellar mass primordial black holes during the early Universe, considering different QCD phase transition models, and finds they could explain gravitational wave sources and make up most of dark matter.

Contribution

It introduces new formation scenarios for stellar mass PBHs incorporating QCD phase transition models and a running-tilt power-law spectrum.

Findings

PBHs of 0.05-500 M$_{igodot}$ can form during early Universe.

Stellar mass PBHs could explain gravitational wave sources.

PBHs may account for approximately 76% of Cold Dark Matter.

Abstract

Primordial Black Holes (PBHs) might have formed in the early Universe due to the collapse of density fluctuations. PBHs may act as the sources for some of the gravitational waves recently observed. We explored the formation scenarios of PBHs of stellar mass, taking into account the possible influence of the QCD phase transition, for which we considered three different models: Crossover Model (CM), Bag Model (BM), and Lattice Fit Model (LFM). For the fluctuations, we considered a running-tilt power-law spectrum; when these cross the $\sim 10^{-9}$-$10^{-1}\mathrm{~s}$ Universe horizon they originate 0.05-500~M$_{\odot}$ PBHs which could: i) provide a population of stellar mass PBHs similar to the ones present on the binaries associated with all known gravitational wave sources; ii) constitute a broad mass spectrum accounting for $\sim 76\%$ of all Cold Dark Matter (CDM) in the Universe.