Quantized fields and temperature in charged dilatonic black hole spacetimes

TL;DR

This paper calculates the stress-energy tensor of a quantized scalar field in a charged dilatonic black hole spacetime, revealing that a nonzero temperature is necessary for regularity at the horizon, even in extreme cases.

Contribution

It demonstrates that assigning a nonzero temperature to the extreme string metric ensures regularity of the quantum stress-energy tensor at the horizon.

Findings

Nonzero temperature is required for regularity at the horizon.

The stress-energy tensor is computed explicitly in the charged dilatonic black hole.

Extreme string metric has a nonzero temperature for regular quantum fields.

Abstract

The stress-energy tensor of a quantized scalar field is computed in the reduced two-dimensional charged dilatonic black hole spacetime of Garfinkle, Horowitz, and Strominger. In order for the stress-energy of quantized fields to be regular on the event horizon in both the extreme string metric and the conformally associated physical metric, it is necessary to assign a nonzero temperature, T = (8 pi e^{phi_0} M)^{-1}, to the extreme string metric, contrary to the expectation that this horizonless spacetime would have a natural temperature of zero.