  An event horizon for "relativistic" fermionic quasiparticles can be
constructed in a thin film of superfluid 3He-A. The quasiparticles see an
effective "gravitational" field which is induced by a topological soliton of
the order parameter. Within the soliton the "speed of light" crosses zero and
changes sign. When the soliton moves, two planar event horizons (black hole and
white hole) appear, with a curvature singularity between them. Aside from the
singularity, the effective spacetime is incomplete at future and past
boundaries, but the quasiparticles cannot escape there because the
nonrelativistic corrections become important as the blueshift grows, yielding
"superluminal" trajectories. The question of Hawking radiation from the moving
soliton is discussed but not resolved.
