Can we measure component spins from black hole binaries?

Gravitational wave (GW) observations of binary black hole (BBH) mergers provide measurements of BBH parameters such as mass and spin, which shed light on the evolutionary history of these systems. Data from the Laser Interferometer Gravitational-wave Observatory (LIGO) currently provides strong constraints on effective spin, a mass weighted average of each black hole's spin projected in the direction of the orbital angular momentum, while the individual spin magnitudes and tilt angles ("component spins") remain weakly constrained for individual events. In this talk, I explore whether we can differentiate synthetic populations with the same effective spin distributions but different underlying component spin distributions. I also discuss our ability to diagnose model misspecification by analyzing posterior predictive plots. This study provides insight into how much information we can extract about component spin of BBH mergers from LIGO data and how we can identify poor model fits, which will prove especially useful with LIGO's upcoming observing run (O4).