Black hole-neutron star mergers resulting in the disruption of the neutron
star and the formation of an accretion disk and/or the ejection of unbound
material are prime candidates for the joint detection of gravitational-wave and
electromagnetic signals when the next generation of gravitational-wave
detectors comes online. However, the disruption of the neutron star and the
properties of the post-merger remnant are very sensitive to the parameters of
the binary. In this paper, we study the impact of the radius of the neutron
star and the alignment of the black hole spin for systems within the range of
mass ratio currently deemed most likely for field binaries (M_BH ~ 7 M_NS) and
for black hole spins large enough for the neutron star to disrupt (J/M^2=0.9).
We find that: (i) In this regime, the merger is particularly sensitive to the
radius of the neutron star, with remnant masses varying from 0.3M_NS to 0.1M_NS
for changes of only 2 km in the NS radius; (ii) 0.01-0.05M_sun of unbound
material can be ejected with kinetic energy >10^51 ergs, a significant increase
compared to low mass ratio, low spin binaries. This ejecta could power
detectable optical and radio afterglows. (iii) Only a small fraction (<3%) of
the Advanced LIGO events in this parameter range have gravitational-wave
signals which could offer constraints on the equation of state of the neutron
star. (iv) A misaligned black hole spin works against disk formation, with less
neutron star material remaining outside of the black hole after merger, and a
larger fraction of that material remaining in the tidal tail instead of the
forming accretion disk. (v) Large kicks (v>300 km/s) can be given to the final
black hole as a result of a precessing BHNS merger, when the disruption of the
neutron star occurs just outside or within the innermost stable spherical
orbit.
