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General Relativity and Quantum Cosmology, gr-qc
Abstract:
We improve the accuracy of the effective-one-body (EOB) waveforms that were
employed during the first observing run of Advanced LIGO for binaries of
spinning, nonprecessing black holes by calibrating them to a set of 141
numerical-relativity (NR) waveforms. The NR simulations expand the domain of
calibration towards larger mass ratios and spins, as compared to the previous
EOBNR model. Merger-ringdown waveforms computed in black-hole perturbation
theory for Kerr spins close to extremal provide additional inputs to the
calibration. For the inspiral-plunge phase, we use a Markov-chain Monte Carlo
algorithm to efficiently explore the calibration space. For the merger-ringdown
phase, we fit the NR signals with phenomenological formulae. After
extrapolation of the calibrated model to arbitrary mass ratios and spins, the
(dominant-mode) EOBNR waveforms have faithfulness --- at design Advanced-LIGO
sensitivity --- above $99\%$ against all the NR waveforms, including 16
additional waveforms used for validation, when maximizing only on initial phase
and time. This implies a negligible loss in event rate due to modeling for
these binary configurations. We find that future NR simulations at mass ratios
$\gtrsim 4$ and double spin $\gtrsim 0.8$ will be crucial to resolve
discrepancies between different ways of extrapolating waveform models. We also
find that some of the NR simulations that already exist in such region of
parameter space are too short to constrain the low-frequency portion of the
models. Finally, we build a reduced-order version of the EOBNR model to speed
up waveform generation by orders of magnitude, thus enabling intensive
data-analysis applications during the upcoming observation runs of Advanced
LIGO.
