Systematic Biases in Estimating the Properties of Black Holes Due to Inaccurate Gravitational-Wave Models

Gravitational-wave (GW) observations of binary black-hole (BBH) coalescences are expected to address outstanding questions in astrophysics, cosmology, and fundamental physics. Inference of BBH parameters relies on waveform models, and realizing the full discovery potential of upcoming LIGO-Virgo-KAGRA observing runs and new ground-based facilities (such as the Einstein Telescope and Cosmic Explorer) hinges on the accuracy of these waveform models. Using linear-signal approximation methods and Bayesian analysis, we start to assess our readiness for what lies ahead using two state-of-the-art quasicircular, spin-precessing models: SEOBNRv5PHM and IMRPhenomXPHM. We find that systematic biases increase with the spin of the BH, with parameter biases being approximately 6 to 8 times likelier, if the primary-spin magnitude exceeds 0.5 compared to when it is less than 0.5. Additionally, we ascertain that current waveforms can accurately recover the distribution of masses in the LVK astrophysical population but not spins. Upon exploring the broader parameter space of BHs, we find that systematic biases increase with detector-frame total mass, binary asymmetry, and spin precession, with a majority of such binaries incurring parameter biases, extending up to redshifts around 3 in future detectors. Furthermore, we examine three "golden" events characterized by mass ratios of approximately 6 to 10, significant spin magnitudes (0.6 - 0.9), and high precession, evaluating how systematic biases may affect their scientific outcomes. Our findings reveal that current waveforms fail to enable the unbiased measurement of the Hubble-Lema & icirc;tre parameter and sky localization from loud signals, even for current detectors. Moreover, highly asymmetric systems within the lower BH mass gap exhibit biased measurements of the secondary-companion mass, which impacts the physics of both neutron stars and formation channels. Similarly, we deduce that the primary mass of massive binaries (> 60M(circle dot)) will also be biased, affecting supernova physics. Future progress in analytical calculations and numerical-relativity simulations, crucial for calibrating the models, must target regions of the parameter space with significant biases to develop more accurate models. Only then can precision GW astronomy fulfill the promise it holds.