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General Relativity and Quantum Cosmology, gr-qc
Abstract:
Future third generation (3G) ground-based GW detectors, such as the Einstein
Telescope and Cosmic Explorer, will have unprecedented sensitivities enabling
studies of the entire population of stellar mass binary black hole coalescences
in the Universe. To infer binary parameters from a GW signal we require
accurate models of the gravitational waveform as a function of black hole
masses, spins, etc. Such waveform models are built from numerical relativity
(NR) simulations and/or semi-analytical expressions in the inspiral. We
investigate the limits of the current waveform models and study at what
detector sensitivity these models will yield unbiased parameter inference for
loud ''golden'' binary black hole systems, what biases we can expect beyond
these limits, and what implications such biases will have for GW astrophysics.
For 3G detectors we find that the mismatch error for semi-analytical models
needs to be reduced by at least \emph{three orders of magnitude} and for NR
waveforms by \emph{one order of magnitude}. In addition, we show that for a
population of one hundred high mass precessing binary black holes, measurement
errors sum up to a sizable population bias, about 10 -- 30 times larger than
the sum of 90\% credible intervals for key astrophysical parameters.
Furthermore we demonstrate that the residual signal between the GW data
recorded by a detector and the best fit template waveform obtained by parameter
inference analyses can have significant SNR ratio. This coherent power left in
the residual could lead to the observation of erroneous deviations from general
relativity. To address these issues and be ready to reap the scientific
benefits of 3G GW detectors in the 2030s, waveform models that are
significantly more physically complete and accurate need to be developed in the
next decade along with major advances in efficiency and accuracy of NR codes.
