  LS 5039 is a TeV gamma-ray binary with extended radio emission. It consists
of a compact object in the mildly eccentric (e=0.35), 3.9-day orbit around a
massive O star. The nature of the compact object is not yet established. In
this paper, assuming that the compact object is a black hole, we study the
accretion of O-star wind by the black hole, by performing three-dimensional
Smoothed Particle Hydrodynamics (SPH) simulations. In order to roughly emulate
the effect of the stellar radiation effectively canceling the stellar gravity,
we assume that the O star's gravity does not exert on the wind. The wind
particles are ejected with half the observed terminal velocity in a narrow
range of azimuthal and vertical angles toward the black hole, in order to
emulate the wind significantly slower than the terminal speed, and optimize the
resolution and computational efficiency of simulations. We find that the
mass-accretion rate closely follows the classical Bondi-Hoyle-Littleton
accretion rate, which is of the order of 10^{16}g/s around periastron. The
accretion rate at this level would provide jets enough power to produce the
gamma-rays detected by HESS. Since the accretion peak occurs near the
periastron passage, we need a strong gamma-ray absorption around periastron in
order for the microquasar scenario to be consistent with the observed orbital
modulation of the TeV gamma-ray flux.
