Frequency-domain gravitational waves from non-precessing black-hole binaries. II. A phenomenological model for the advanced detector era (1508.07253v2)

Abstract: We present a new frequency-domain phenomenological model of the gravitational-wave signal from the inspiral, merger and ringdown of non-precessing (aligned-spin) black-hole binaries. The model is calibrated to 19 hybrid effective-one-body--numerical-relativity waveforms up to mass ratios of 1:18 and black-hole spins of $|a/m| \sim 0.85$ ($0.98$ for equal-mass systems). The inspiral part of the model consists of an extension of frequency-domain post-Newtonian expressions, using higher-order terms fit to the hybrids. The merger-ringdown is based on a phenomenological ansatz that has been significantly improved over previous models. The model exhibits mismatches of typically less than 1\% against all 19 calibration hybrids, and an additional 29 verification hybrids, which provide strong evidence that, over the calibration region, the model is sufficiently accurate for all relevant gravitational-wave astronomy applications with the Advanced LIGO and Virgo detectors. Beyond the calibration region the model produces physically reasonable results, although we recommend caution in assuming that \emph{any} merger-ringdown waveform model is accurate outside its calibration region. As an example, we note that an alternative non-precessing model, SEOBNRv2 (calibrated up to spins of only 0.5 for unequal-mass systems), exhibits mismatch errors of up to 10\% for high spins outside its calibration region. We conclude that waveform models would benefit most from a larger number of numerical-relativity simulations of high-aligned-spin unequal-mass binaries.

• The paper presents a phenomenological model that captures the inspiral, merger, and ringdown phases of non-precessing black-hole binaries.
• It calibrates the model against 19 hybrid EOB/NR waveforms, achieving mismatches below 1% over a wide parameter range.
• Methodological enhancements include modular frequency segmentation and refined phase modeling, improving reliability for advanced GW detection.

An Analysis of Frequency-Domain Gravitational Waves from Non-Precessing Black-Hole Binaries

The paper presents a refined model to describe the gravitational wave (GW) emission from non-precessing (aligned-spin) black hole binaries (BBH), particularly suitable for the advanced detector era, such as Advanced LIGO and Virgo. This research focuses on creating a phenomenological frequency-domain model that captures the inspiral, merger, and ringdown phases of black hole coalescence, providing enhancements over previous models like PhenomB and PhenomC.

Model Calibration and Validation

The authors have calibrated the model against 19 hybrid waveforms derived from a combination of effective-one-body (EOB) and numerical relativity (NR) simulations. This calibration encompasses mass ratios up to 1:18 and black hole spins reaching approximately 0.85, extending to 0.98 for equal-mass systems. The model strives to minimize mismatches to below 1% in the calibrated range, which is crucial for the forthcoming era of precise GW astronomy.

Methodological Enhancements

The model is constructed by dividing the frequency spectrum into distinct regions, with each section being independently characterized and yet smoothly connected to neighboring segments. This modular approach not only increases the model's accuracy but also offers flexibility for future modifications. Researchers refine the inspiral region using extended post-Newtonian (PN) expressions aligned with hybrid EOB/NR data, whereas the merger-ringdown phase has been significantly improved via a new phenomenological ansatz, which refines phase modeling over the frequency domain.

Strong Numerical Results

Upon comparison with SEOBNRv2, particularly in high-spin, unequal-mass scenarios, this model outperforms with reduced mismatch errors, suggesting potential inadequacies of SEOBNRv2 models when applied outside their calibrated domain. This insight is vital for high-fidelity waveform modeling across broader parameter spaces.

Theoretical and Practical Implications

From a theoretical vantage, the resultant model offers an enriched representation of BBH waves, reinforcing the necessity for extensive NR simulations across varied mass and spin configurations. Practically, such advancements fulfill critical requirements for GW detection and parameter estimation, facilitating the extraction of astrophysical and fundamental physics insights from observational data.

Speculations on Future Developments

As future directions, expanding numerical relativity datasets across extremal parameter regimes is likely to augment waveform accuracy and reliability further. Moreover, integrating insights from this model into precessing binaries could yield a comprehensive toolkit for all expected astrophysical sources in the advanced detector era.

Overall, this research makes a significant contribution to the computational armamentarium required for precise GW astronomy, by extending the reach and robustness of phenomenological models beyond traditional boundaries.