Explosibility fluctuations of massive stellar cores enable asymmetric compact object mergers like GW190814

The first three observing runs with Advanced LIGO and Virgo have detected a handful of binary black hole mergers (BBH) with highly unequal mass components that are difficult to reconcile with standard formation paradigms. The most extreme of these is GW190814, a highly asymmetric merger between a 23 M$_{\odot}$~black hole and a 2.6 M$_{\odot}$~compact object. Here, we employ recent results presented in Aguilera-Dena et al. (2021), suggesting that a sizeable fraction of stars with pre-collapse masses $\gtrsim 10$ M$_{\odot}$ may produce objects inside the so-called lower mass gap that bridges the division between massive pulsars and BHs in Galactic X-ray binaries. We argue that such an explosion landscape would naturally cause a fraction of massive binaries to produce asymmetric -- instead of symmetric-mass BBHs. We present examples of specific evolutionary channels leading to the formation of GW190814 and estimate the merger-rate density of these events in our scenario to be $\mathcal{O}$(5%) of the total BBH merger rate. We also discuss the broader implications of this formation channel for compact object populations, and its possible relevance to other merger events such as GW200115 and GW200105.