Understanding GW191109: Robust Glitch Mitigation and Its Astrophysical Implications*

One of the most interesting gravitational wave events from the LVK’s third observing run was GW191109_010717 (GW191109), which possesses support for high, asymmetric component masses and high component spins anti-aligned with the orbital angular momentum. This has led to significant interest in the event as one of the most promising candidates for a hierarchical formation scenario. However, GW191109 is coincident with terrestrial noise transients (“glitches”) in both detectors, and previous works have found that changes to glitch mitigation techniques may erase support for astrophysically interesting spin configurations. Here, we present a thorough analysis of this event. First, we reproduce the results of previous analyses and investigate the implications of their glitch mitigation methods. We next apply two parameter estimation techniques which have not yet been used on this event: joint inference with a physically motivated model of the coincident scattered light glitches, and time-domain analyses which exclude segments of the data in time. We discuss the merits and shortcomings of each approach, as well as the astrophysical implications of results in each scenario.