We investigate the possible dynamical origin of GW190814, a gravitational wave (GW) source discovered by the LIGO-Virgo-Kagra collaboration (LVC) associated with a merger between a stellar black hole (BH) with mass $23.2$ M$_odot$ and a compact object, either a BH or a neutron star (NS), with mass $2.59$ M$_odot$. Using a database of 240,000 $N$-body simulations modelling the formation of NS-BH mergers via dynamical encounters in dense clusters, we find that systems like GW190814 are likely to form in young, metal-rich clusters. Our model suggests that a little excess ($sim 2-4%$) of objects with masses in the range $2.3-3$ M$_odot$ in the compact remnants mass spectrum leads to a detection rate for dynamically formed GW190814 -like mergers of $Gamma_{rm GW190814} simeq 1-6$ yr Gpc$^{-3}$, i.e. within the observational constraints set by the GW190814 discovery, $Gamma_{rm LVC} sim 1-23$ yr Gpc$^{-3}$. Additionally, our model suggests that $sim 1.8-4.8%$ of dynamical NS-BH mergers are compatible with GW190426_152155, the only confirmed NS-BH merger detected by the LVC. We show that the relative amount of light and heavy NS-BH mergers can provide clues about the environments in which they developed.
Download