Could the 2.6 $M_\odot$ object in GW190814 be a primordial black hole?

TL;DR

This paper examines whether the 2.6 solar mass object in GW190814 could be a primordial black hole, concluding that such an explanation is unlikely due to formation rate constraints and observed merger rates.

Contribution

The study provides a detailed analysis of primordial black hole scenarios for GW190814's secondary object, highlighting limitations based on formation and merger rate observations.

Findings

Primordial black hole explanation for GW190814 is unlikely.

Formation rate constraints limit primordial black hole scenarios.

Observed merger rates of massive black holes challenge the PBH hypothesis.

Abstract

On June 20, 2020, the LIGO-Virgo collaboration announced the discovery of GW190814, a gravitational wave event originating from a binary system merger between a black hole of mass $M_1 = 23.2^{+1.1} _ {-1.0}M_\odot$ and an unidentified object with a mass of $M_2 = 2.59^{+0.08} _ {-0.09}M_\odot$. This second object would be either the heaviest neutron star or lightest black hole observed to date. Here we investigate the possibility of the $\sim 2.6M_\odot$ object being a primordial black hole (PBH). We find that a primordial black hole explanation to GW190814 is unlikely as it is limited by the formation rate of the primary stellar progenitor and the observed merger rates of $\mathcal{O}(20)M_\odot$ massive black hole pairs.