Event horizons and ergoregions in ³He

Event horizons for fermion quasiparticles naturally arise in moving textures in superconductors and Fermi superfluids. We discuss the example of a planar soliton moving in a superfluid ³He-A, which is closely analogous to a charged rotating black hole. The moving soliton will radiate quasiparticles via the Hawking effect at a temperature of about 5 μK, and via vacuum polarization induced by the effective “electromagnetic field” and “ergoregion.” The superfluid ³He-A thus appears to be a useful system for experimental and theoretical simulations of quantum effects related to event horizons and ergoregions.