The Nature of Gravitational Wave Events with Host Environment Escape Velocities

Abstract We propose a novel method to probe the parameters and origin channels of gravitational wave events using the escape velocities of their host environments. This method could lead to more convergent posterior distributions offering additional insights into the physical properties, formation, and evolution of the sources. The method provides more accurate parameter estimation for events that represent previous mergers in the hierarchical triple merger scenario and is valuable for the search for such mergers with third-generation ground-based detectors. To demonstrate this approach, we take six recently identified events in LIGO–Virgo–KAGRA (LVK) data, considered as potential previous mergers in hierarchical triple mergers, as examples. The use of escape velocities results in posterior spin distributions that are concentrated near zero, aligning with the expected birth spins of first-generation black holes formed from the collapse of stars. The uncertainty in the posterior primary mass distribution is significantly reduced comparing with the LVK distributions, especially for events modeled under the assumption of a globular cluster (GC) origin scenario. We rule out the possibility that GW190512, GW170729, and GW190708 originate from GCs as previous mergers in the hierarchical triple merger scenario.