  Transonic accretion onto astrophysical objects is a unique example of
analogue black hole realized in nature. In the framework of acoustic geometry
we study axially symmetric accretion and wind of a rotating astrophysical black
hole or of a neutron star assuming isentropic flow of a fluid described by a
polytropic equation of state. In particular we analyze the causal structure of
multitransonic configurations with two sonic points and a shock. Retarded and
advanced null curves clearly demonstrate the presence of the acoustic black
hole at regular sonic points and of the white hole at the shock. We calculate
the analogue surface gravity and the Hawking temperature for the inner and the
outer acoustic horizons.
