The SXS Collaboration catalog of binary black hole simulations (1904.04831v2)

Abstract: Accurate models of gravitational waves from merging black holes are necessary for detectors to observe as many events as possible while extracting the maximum science. Near the time of merger, the gravitational waves from merging black holes can be computed only using numerical relativity. In this paper, we present a major update of the Simulating eXtreme Spacetimes (SXS) Collaboration catalog of numerical simulations for merging black holes. The catalog contains 2018 distinct configurations (a factor of 11 increase compared to the 2013 SXS catalog), including 1426 spin-precessing configurations, with mass ratios between 1 and 10, and spin magnitudes up to 0.998. The median length of a waveform in the catalog is 39 cycles of the dominant $\ell=m=2$ gravitational-wave mode, with the shortest waveform containing 7.0 cycles and the longest 351.3 cycles. We discuss improvements such as correcting for moving centers of mass and extended coverage of the parameter space. We also present a thorough analysis of numerical errors, finding typical truncation errors corresponding to a waveform mismatch of $\sim 10^{-4}$. The simulations provide remnant masses and spins with uncertainties of 0.03% and 0.1% ($90^{\text{th}}$ percentile), about an order of magnitude better than analytical models for remnant properties. The full catalog is publicly available at https://www.black-holes.org/waveforms .

• The paper presents an expanded catalog of 2018 simulations, including 1426 spin-precessing cases that notably broaden the parameter space for binary black hole mergers.
• It employs high-accuracy spectral methods and advanced center-of-mass corrections to precisely model gravitational waveforms from black hole coalescences.
• The results significantly enhance gravitational wave astronomy by improving model comparisons and predictions of remnant black hole properties.

Overview of the SXS Collaboration Catalog of Binary Black Hole Simulations

The paper presented by the SXS Collaboration introduces a significant update to their catalog of numerical simulations of binary black hole (BBH) systems. This discussion focuses on the methodologies employed, the improvements made over previous catalogs, and the implications for gravitational wave astronomy.

Key Contributions

• Expansion of Catalog: The catalog now includes 2018 simulations of merging black holes, marking a substantial increase from previous efforts. It features 1426 simulations with spin-precessing configurations and covers mass ratios between 1 and 10, with spin magnitudes extending to 0.998. This scale of expansion allows for a more comprehensive analysis of the parameter space relevant to BBH mergers.
• Numerical Accuracy and Techniques: A central feature of the paper is the description of the numerical methods used, notably the Spectral Einstein Code (SpEC), which is essential for achieving high accuracy in the simulation of relativistic dynamics near the time of merger. The use of spectral methods enhances the precise resolution of the Einstein field equations during black hole coalescence.
• Center-of-Mass Corrections: The authors introduce techniques to correct for center-of-mass (COM) motion, which ensures that the gravitational waveforms extracted from simulations do not suffer from unphysical modulations due to shifts in the simulation's coordinate system.
• Waveform Extrapolation: Extrapolation of the gravitational waveforms to future null infinity is rigorously described, which is crucial for aligning numerical relativity results with observational data collected by LIGO and Virgo detectors.

Implications

• Gravitational Wave Astronomy: The expanded SXS catalog provides indispensable resources for the detection and parameter estimation of gravitational wave events. The increased number of simulations and improved accuracy directly enhance the construction of waveform models, which are used to extract physical information from gravitational wave signals.
• Model Comparison: The paper's comprehensive analysis of waveform comparisons and mismatches due to resolution differences provides insights into the reliability of numerical simulations. The small mismatches observed in most simulations affirm the robustness of SpEC and the employed numerical techniques.
• Remnant Black Hole Properties: By comparing numerical results with analytical models for remnant properties, such as mass, spin, and recoil velocity, the paper provides a critical evaluation of the accuracy of predictive models.

Future Directions

The paper hints at several areas for future exploration, such as extending the parameter space coverage to even higher mass ratios and spin magnitudes, improving initial data to reduce spurious artifacts, and leveraging Cauchy-characteristic extraction methods for more accurate wave extraction. These developments aim to provide waveforms that are both longer in orbit coverage and reduced in numerical error, thereby enabling new insights into the dynamics of strong gravitational fields.

In conclusion, the SXS Collaboration's updated catalog marks a significant advancement in our ability to understand and interpret the complex gravitational waves emitted by binary black hole systems. The rigorous development and dissemination of accurate waveform data ensure continued progress in the field of gravitational wave astronomy.