Fast LISA response functions for massive black hole binaries

Abstract

LISA is a space-based gravitational wave observatory under development by the European Space Agency (ESA), designed to detect low-frequency signals from sources such as massive and stellar-mass black hole binaries. To process the signals LISA (Laser Interferometer Space Antenna) will observe, it is necessary to model its detector response accurately. In this work, we implement LISA’s noise-free frequency-domain response using the IMRPhenomD waveform model. The response is implemented in JAX, which provides efficient numerical computation and support for automatic differentiation. Our model accounts for the constellation’s motion and Time Delay Interferometry (TDI) observables. We validate the resulting strain signals using the BBHx simulation code, finding overlaps above 0.99999999 across all TDI channels and mass ranges, which demonstrates the reliability of our implementation