2021ApJ...907L..24S

In its third observing run, the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration has announced a potential neutron star-black hole (NS-BH) merger candidate, GW190426_152155. Together with GW190814, these two events belong to a class of binaries with a secondary mass less than 3 M_☉. While the secondary system in GW190426_152155 is consistent with being a neutron star (NS) with a mass of 1.5_–0.5^+0.8M_☉, that of GW190814 is a 2.59_–0.09^+0.08M_☉ object and counts as the first confirmed detection of a mass-gap object. Here we argue that these two events could have a common origin as follows: both are formed as NS-BH systems; however, the larger escape velocity of a system with more massive primary black hole (BH) increases the bound fraction of the ejecta material from the supernova explosion leading to the formation of a NS. This bound material forms a disk, which is preferentially accreted onto the NS. This scenario predicts the secondary component mass should correlate with the primary component mass, which is consistent with GW190426_152155 and GW190814. If this hypothesis is corroborated by upcoming observations, GW190814-like events can be excluded from the binary BH population when inferring their global characteristics.