AthenaK simulations of the binary black hole merger GW150914

Abstract: We present new binary black hole simulations targeted to GW150914 using the GPU-accelerated code \texttt{AthenaK}. We compute the properties of the final remnant with the isolated horizon formalism and obtain gravitational-waveforms at future null infinity via Cauchy characteristic extraction. We compare our results with those obtained by the Simulating eXtreme Spacetimes (SXS) and Rochester Institute of Technology (RIT) groups, targeted to the same event. We find excellent agreement in the remnant mass, spin, and recoil velocity. For the dominant $(\ell,m)=(2,2)$ mode of the gravitational-wave signal we find maximum dephasing of $\Delta \phi \simeq 0.35$ and amplitude difference of $\Delta A/A \simeq 0.4\%$. We use our newly computed waveform to re-analyze the GW150914 data and find posteriors for chirp mass, luminosity distance, and inclination that are broadely consistent with those obtained using semi-analytic waveform models. This work demonstrates the viability of \texttt{AthenaK} for many-orbits binary black hole merger simulations. A step-by-step tutorial, including all necessary input files and analysis scripts to reproduce our results, is available on \texttt{GitHub}.