After the discovery of gravitational waves from binary black holes (BBHs) and
binary neutron stars (BNSs) with the LIGO and Virgo detectors,
neutron-star--black-holes (NSBHs) are the natural next class of binary systems
to be observed. In this work, we develop a waveform model for aligned-spin
neutron-star--black-holes (NSBHs) combining a BBH baseline waveform (available
in the effective-one-body approach) with a phenomenological description of
tidal effects (extracted from numerical-relativity simulations), and correcting
the amplitude during the late inspiral, merger and ringdown to account for the
NS tidal disruption. We calibrate the amplitude corrections using NSBH
waveforms obtained with the SpEC and the SACRA codes. The model was calibrated
using simulations with NS masses in the range $1.2-1.4 M_\odot$, tidal
deformabilities up to $4200$ (for a 1.2 $M_\odot$ NS), and dimensionless BH
spin magnitude up to 0.9. Based on the simulations used, and on checking that
sensible waveforms are produced, we recommend our model to be employed with NS
mass in the range $1\mbox{--}3 M_\odot$, tidal deformability $0\mbox{--}5000$,
and BH spin magnitude up to $0.9$. We also validate our model against two new,
highly accurate NSBH waveforms with BH spin 0.9 and mass ratios 3 and 4,
characterized by tidal disruption, produced with SpEC, and find very good
agreement. We find that it will be challenging for the advanced
LIGO-Virgo--detector network at design sensitivity to distinguish different
source classes. We perform parameter-estimation on a synthetic
numerical-relativity signal in zero noise to study parameter biases. Finally,
we reanalyze GW170817, with the hypothesis that it is a NSBH. We do not find
evidence to distinguish the BNS and NSBH hypotheses, however the posterior for
the mass ratio is shifted to less equal masses under the NSBH hypothesis.
[Abstract abridged for arxiv].
