GR-Athena++ simulations of spinning binary black hole mergers

We present the second release of the GR-Athena++ waveform catalog, comprising four new quasi-circular, non-precessing, spinning binary black hole simulations. These simulations are performed at high resolutions and represent a step toward generating high-fidelity gravitational waveforms that can eventually meet the accuracy requirements of upcoming next-generation detectors, including LISA, cosmic explorer, and Einstein Telescope. Gravitational waves are extracted at future null infinity ( I+) using both Cauchy characteristic extraction and finite-radius extraction. For each simulation, we provide strain data across multiple resolutions and analyze waveform accuracy via convergence studies and self-mismatch analyses. The absolute phase and relative amplitude differences reach their largest values near the merger, while the smallest errors are of order O(10−2) and O(10−3), respectively. A self-mismatch analysis of the dominant (2, 2) mode yields mismatches between O(10−5) and O(10−7) for a total binary mass of 106M⊙ over the frequency range f∈[0.002,0.1]Hz using LISA’s noise curve. All waveforms are publicly available via ScholarSphere.