Hot origin of the Little Bang

Ultrarelativistic heavy ion collisions produce a quark-gluon matter which lies in the future light cone originating from given points on the $t=z=0$ plane of the Minkowski spacetime manifold. We show that in a weak coupling regime the Minkowski vacuum of massless fields presents itself for low $p_{T}$ particles as a thermal state in the "Little Bang" region, in close analogy to the Unruh effect for uniformly accelerated observers which are causally restricted to a Rindler wedge. It can shed some light on the mechanisms of early time thermalization of long-wavelength modes in ultrarelativistic heavy ion collisions.