Acoustic Black Hole (Dumb Hole)

Flow speed v: 1.50 Sound speed c_s: 1.00 Hawking T: 0.30

Mach #: — | Horizon: — | T_Hawking: —

Unruh (1981): phonons in supersonic flow ≡ Hawking radiation. Horizon where v=c_s. T_H=ℏκ/2πk_B (κ=surface gravity). BEC realization (Steinhauer 2016).