Analysis of GWTC-3 with multiple quasicircular models
The interpretation of gravitational wave sources depends on the specific choice of model used to interpret signals. Previous analyses of GWTC-3 event candidates using SEOBNRv4PHM, IMRPhenomXPHM, and NRSur7dq4 have sometimes arrived at notably different conclusions about event properties. Subtle analysis settings and code differences can also produce notable differences. We revisit 60 publicly available events from the first three observing runs, released across GWTC-1, GWTC-2, GWTC-2.1, and GWTC-3, using a consistent analysis framework and three waveform models: two state-of-the-art time-domain models with higher-order modes (SEOBNRv5PHM and IMRPhenomTPHM) and one older frequency-domain model without higher-order modes (IMRPhenomPv2). The two state-of-the-art models agree well overall, although about 20\% of events have a visible difference in at least one one-dimensional marginal posterior. By contrast, the older model often arrives at qualitatively different conclusions for key events across the mass spectrum. We also identify a bug in published LVK GWTC-2.1 SEOBNRv4PHM results and in a later reprocessing of GW200105. At the adopted sampling rates, the model's Nyquist-frequency restriction excluded part of the allowed parameter space and artificially truncated the mass-ratio posterior away from equal mass for seven low-mass events. These results emphasize the need to use multiple state-of-the-art waveform models and carefully validated analysis settings to characterize uncertainty in gravitational-wave source properties.