Presentation #234.05 in the session “Compact Mergers Observed & Compact Binary Populations through Gravitational Waves”.
The heaviest neutron stars and lightest black holes expected to be produced by stellar evolution leave the mass-range of 2.2-5 solar masses largely unpopulated. Objects found in this so-called lower mass gap likely originate from a distinct astrophysical process. Such an object, with mass 2.6 solar masses was recently detected in the binary merger GW190814 through gravitational waves by LIGO/Virgo. I will show that black holes in the mass gap are naturally assembled through mergers and accretion in AGN disks, and can subsequently participate in additional mergers. I will present the properties of AGN-assisted mergers involving neutron stars and black holes, accounting for accretion. Our results show that mergers in which one of the objects is in the lower mass gap represent up to 4% of AGN-assisted mergers detectable by LIGO/Virgo. The lighter object of GW190814, with mass 2.6 solar masses, could have grown in an AGN disk through accretion.