Population-rate calculation for GW190814-like mergers

Determine the formation and merger rate of GW190814-like binary black hole systems formed through isolated binary evolution by performing a full rate calculation that integrates over the metallicity-dependent star formation history and accounts for binary survival across cosmic time.

Background

Using BackPop with COSMIC, the study identifies a preferred formation pathway for GW190814-like binaries that requires a low first natal kick and a large, in-plane second natal kick that raises eccentricity, enabling a merger within a Hubble time. The authors estimate that the required kick geometry occurs with a probability of approximately 20% under isotropic kicks.

To translate this geometric probability into an astrophysical event rate, the authors note that one must integrate over the metallicity-dependent star formation history and account for binary survival across cosmic time. They explicitly defer this calculation, which would quantify the rarity of GW190814-like events within cosmic populations.