High-accuracy modeling techniques for intermediate mass ratio waveform models based on perturbation theory calibrated to numerical relativity

Recent advancements in surrogate models of gravitational waves based on point particle black hole perturbation theory (ppBHPT) have enabled the efficient generation of high-fidelity waveforms for binary black hole (BBH) mergers. A distinguishing feature of these ppBHPT-based models is their simple calibration to numerical relativity (NR) through phase and amplitude rescalings, known as α-β scaling where α and β are time-independent constants. This technique broadens the applicability of ppBHPT-based waveforms to regimes involving comparable to intermediate mass ratios. However, due to the time-independent assumption of α-β scaling, the current calibration method suffers reduced accuracy near late-inspiral through ringdown. This presentation will highlight improvements in calibration techniques, including the introduction of time-varying α-β parameters to better track the waveform's evolution as well as a ringdown surrogate to further enhance waveform accuracy. I will present the latest progress in these calibration refinements and discuss ongoing efforts to improve ringdown modeling.