Potential science with GW250114 -- the loudest binary black hole merger detected to date

On January 14, 2025 the LIGO interferometers detected a gravitational wave from the merger of two black holes, GW250114. Using publicly available information, we estimate that the signal-to-noise ratio (SNR) of GW250114 was $\sim 80$. This would make it three to four times louder than any other gravitational wave detected to date. GW250114 therefore offers a unique opportunity to make precise measurements of its source parameters and to test general relativity. In anticipation of its public data release, we analyze a set of simulated signals that have parameters similar to what we estimate for GW250114 and explore what new insights may be gained from this significant event. We investigate how well the component spins may be constrained, whether any eccentricity may be measured, what quasi-normal modes (QNMs) may be detected in the post-merger signal, how well the black hole area theorem may be constrained, and what constraints may be expected on sub-dominant inspiral-merger-ringdown modes. We find that it should be possible to measure a non-zero eccentricity at $20\,$Hz ($e_{20}$) if GW250114 has $e_{20} \gtrsim 0.05$. We also find that at least one overtone of the dominant QNM should be detectable in the ringdown of GW250114, with a Bayes factor of $O(10^3)$ after marginalizing over all timing uncertainties.