Short-distance contribution to the spectrum of Hawking radiation

The Hawking effect can be rederived in terms of two-point functions and in such a way that it makes it possible to estimate, within the conventional semiclassical theory, the contribution of ultrashort distances to the Planckian spectrum. For Schwarzschild black holes of three solar masses the analysis shows that Hawking radiation is very robust up to frequencies of 96TH or 270TH for bosons and fermions, respectively. For primordial black holes (with masses around 10g) these frequencies turn out to be of order 52TH and 142TH. Only at these frequencies and above do we find that the contribution of Planck distances is of order of the total spectrum itself. Below this scale, the contribution of ultrashort distances to the spectrum is negligible. This suggests that only above these frequencies could an underlying quantum theory of gravity potentially predict significant deviations from Hawking’s semiclassical result. PACS: 04.62.+v,04.70.Dy [email protected] [email protected] [email protected] [email protected]