Understanding Eccentricity and Precession II: Can we measure accurately with incomplete models?

Eccentricity is a key observable to infer the origin of a gravitational wave (GW) source. While there have been many recent studies using eccentric state-of-the-art GW models, models incorporating both spin precession and eccentricity are only in their infancy. Understanding our ability to measure these parameters without all the physics incorporated into the models will be vital for inferring the formation of a binary. To this end, we present a two-part study on the distinguishability of these two key parameters. In this work, we focus on analyzing signals simulated from numerical relativity (NR) simulations of BBH mergers with both eccentricity and spin precession. We conduct two Bayesian parameter estimation analyses on these simulated signals: assuming only eccentric systems and only precessing systems. We then compare results to the corresponding NR generated quasi-circular precessing signals; we asses our ability to measure each parameter using eccentric-only or precession-only models. To illustrate the bias in different parts of parameter space, we analyze signals across masses and distances.