Precursor emission has been observed seconds to minutes before some short
gamma-ray bursts. While the origins of these precursors remain unknown, one
potential explanation relies on the resonance of neutron star pulsational modes
with the tidal forces during the inspiral phase of a compact binary merger. In
this paper, we present a model for short gamma-ray burst precursors which
relies on tidally resonant neutron star oceans. In this scenario, the onset of
tidal resonance in the crust-ocean interface mode corresponds to the ignition
of the precursor flare, possibly through the interaction between the excited
neutron star ocean and the surface magnetic fields. From just the precursor
total energy, the time before the main event, and a detected quasi-periodic
oscillation frequency, we may constrain the binary parameters and neutron star
ocean properties as never before. Our model can immediately distinguish neutron
star-black hole mergers from binary neutron star mergers without gravitational
wave detection. We apply our model to GRB 211211A, the recently detected long
duration short gamma-ray burst with a quasi-periodic precursor, and explore the
parameters of this system within its context. The precursor of GRB 211211A is
consistent with a tidally resonant neutron star ocean explanation that requires
an extreme-mass ratio NSBH merger and a high mass neutron star. While difficult
to reconcile with the gamma-ray burst main emission and associated kilonova,
our results constrain the possible precursor generating mechanisms in this
system. A systematic study of short gamma-ray burst precursors with the model
presented here can test precursor origin and could probe the possible
connection between gamma-ray bursts and neutron star-black hole mergers.Comment: 9 pages, 2 figures, accepted in MNRA