Gravitational waves emitted by neutron star black hole mergers encode key
properties of neutron stars - such as their size, maximum mass and spins - and
black holes. However, the presence of matter and the high mass ratio makes
generating long and accurate waveforms from these systems hard to do with
numerical relativity, and not much is known about systematic uncertainties due
to waveform modeling. We simulate gravitational waves from neutron star black
hole mergers by hybridizing numerical relativity waveforms produced with the
SpEC code with a recent numerical relativity surrogate NRHybSur3dq8Tidal. These
signals are analyzed using a range of available waveform families, and
statistical and systematic errors are reported. We find that at a network
signal-to-noise ratio (SNR) of 30, statistical uncertainties are usually larger
than systematic offsets, while at an SNR of 70 the two become comparable. The
individual black hole and neutron star masses, as well as the mass ratios, are
typically measured very precisely, though not always accurately at high SNR. At
a SNR of 30 the neutron star tidal deformability can only be bound from above,
while for louder sources it can be measured and constrained away from zero. All
neutron stars in our simulations are non-spinning, but in no case we can
constrain the neutron star spin to be smaller than $\sim0.4$ (90% credible
interval). Waveform families whose late inspiral has been tuned specifically
for neutron star black hole signals typically yield the most accurate
characterization of the source parameters. Their measurements are in tension
with those obtained using waveform families tuned against binary neutron stars,
even for mass ratios that could be relevant for both binary neutron stars and
neutron star black holes mergers.
