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

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.