A Gravitational Waveform Model for Detecting Accelerating Inspiraling Binaries

Abstract: We present an analytic frequency-domain gravitational waveform model for an inspiraling binary whose center-of-mass undergoes a small acceleration, assumed to be constant during the detection, such as when it orbits a distant tertiary mass. The center-of-mass acceleration along the line of sight is incorporated as a new parameter that perturbs the standard TaylorF2 model. We calculate the wave phase to 3rd post-Newtonian order and first order in the acceleration. It is shown that acceleration most significantly modifies the wave phase in the low frequency portion of the signal, so ground-based detectors with a good sensitivity at low frequencies are the most effective at detecting this effect. We present a Fisher information calculation to quantify the detectability of this effect at advanced LIGO A Plus, Cosmic Explorer, and Einstein Telescope over the mass range of neutron stars and stellar-mass black holes, and discuss degeneracy between acceleration and other parameters. We also determine the parameter space where the acceleration is large enough that the wave phase model would have to be extended to nonlinear orders in the acceleration.