Gray-body factor and infrared divergences in 1D BEC acoustic black holes.

It is shown that the gray-body factor for a one-dimensional elongated Bose-Einstein condensate (BEC) acoustic black hole with one horizon does not vanish in the low-frequency (ω → 0) limit. This implies that the analog Hawking radiation is dominated by the emission of an infinite number (1/ω) of soft phonons in contrast with the case of a Schwarzschild black hole where the gray-body factor vanishes as ω → 0 and the spectrum is not dominated by low-energy particles. The infrared behaviors of certain correlation functions are also discussed. [ABSTRACT FROM AUTHOR]