Merging black holes with Cauchy-characteristic matching: Computation of late-time tails

Abstract: Cauchy-characteristic matching (CCM) is a numerical-relativity technique that solves Einstein's equations on an effectively infinite computational domain, thereby eliminating systematic errors associated with artificial boundary conditions. Whether CCM can robustly handle fully nonlinear, dynamical spacetimes, such as binary black hole (BBH) mergers, has remained an open question. In this work, we provide a positive answer by presenting nine successful CCM simulations of BBHs; and demonstrate a key application of this method: computing late-time tails. Our results pave the path for systematic studies of late-time tails in BBH systems, and for producing highly accurate waveforms essential to next-generation gravitational-wave detectors.