Accelerating the evaluation of inspiral-merger-ringdown waveforms with adapted grids

This paper presents an algorithm to accelerate the evaluation of inspiral-merger-ringdown waveform models for gravitational wave data analysis. While the idea can also be applied in the time domain, here we focus on the frequency domain, which is most typically used to reduce computational cost in gravitational wave data analysis. Our work extends the idea of multibanding Vinciguerra S et al (2017 Class. Quantum Grav. 34 115006), which has been developed to accelerate frequency domain waveforms, to include the merger and ringdown and spherical harmonics beyond the dominant quadrupole spherical harmonic. The original method of Vinciguerra S et al (2017 Class. Quantum Grav. 34 115006) is based on a heuristic algorithm based on the inspiral to de-refine the equi-spaced frequency grid used for data analysis where a coarser grid is sufficient for accurate evaluation of a waveform model. Here we use a different criterion, based on the local interpolation error, which is more flexible and can easily be adapted to general waveforms, if their phenomenology is understood. We discuss our implementation in the LIGO Algorithms Library (The LIGO Scientific Collaboration 2015 ) for the IMRPhenomXHM Garcia Quiros C et al (2020 arXiv:) frequency domain model, and report the acceleration in different parts of the parameter space of compact binary systems.