%0 Journal Article
%T Hawking radiation as perceived by different observers (ERE2011 proceedings)
%A Luis C. Barbado
%A Carlos Barcel¨®
%A Luis J. Garay
%J Physics
%D 2012
%I arXiv
%R 10.1063/1.4734435
%X We study the perception of Hawking radiation by different observers outside a black hole. The analysis is done in terms of an effective-temperature function that varies along the trajectory of each observer. The vacuum state of the radiation field is chosen to be non-stationary, so as to mimic the switching-on of Hawking radiation that would appear in a real black hole collapse. We analyse how this vacuum is perceived by observers staying at a fixed radius, by observers coming in free-fall from radial infinity at different times, and by observers in free-fall released from finite radial positions. Results found have a compelling physical interpretation. One main result, at first unexpected, is that in general free-falling observers do perceive particle emission by the black hole when crossing the event horizon. This happens because of a diverging Doppler shift at the event horizon.
%U http://arxiv.org/abs/1203.5407v2