“…The experimental realization of vortex states in rotating trapped atomic BECs [6,7], brought the acoustic black-hole analogy into the BEC superfluid [8,2]. The acoustic superradiance and even the Penrose process in both BEC superfluids and classical fluids have been suggested in the literature [9,10,11], and quickly gained momentum as an active research subject. Eventually, an acoustic black hole in a needle-shaped BEC of 87Rb is experimentally demonstrated and recently spontaneous Hawking radiation, stimulated by quantum vacuum fluctuations, emanating from an analogue black hole in an atomic BEC is reported [12,13,14].…”