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 [0.002,0.1] Hz using LISA noise curve. All waveforms are publicly available via ScholarSphere.
@article{arxiv.2510.13963,
title = {$\texttt{GR-Athena++}$ Simulations of Spinning Binary Black Hole Mergers},
author = {Estuti Shukla and Alireza Rashti and Rossella Gamba and David Radice and Koustav Chandra},
journal= {arXiv preprint arXiv:2510.13963},
year = {2026}
}