Unruh–DeWitt Detectors in Spherically Symmetric Dynamical Space-Times |
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Authors: | G Acquaviva R Di Criscienzo M Tolotti L Vanzo and S Zerbini |
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Institution: | (1) Dipartimento di Fisica, Universit? di Trento and Istituto Nazionale di Fisica Nucleare, Via Sommarive 14, 38123 Povo, Italy |
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Abstract: | In the present paper, Unruh–DeWitt detectors are used in order to investigate the issue of temperature associated with a spherically
symmetric dynamical space-times. Firstly, we review the semi-classical tunneling method, then we introduce the Unruh–DeWitt
detector approach. We show that for the generic static black hole case and the FRW de Sitter case, making use of peculiar
Kodama trajectories, semiclassical and quantum field theoretic techniques give the same standard and well known thermal interpretation,
with an associated temperature, corrected by appropriate Tolman factors. For a FRW space-time interpolating de Sitter space
with the Einstein–de Sitter universe (that is a more realistic situation in the frame of ΛCDM cosmologies), we show that the detector response splits into a de Sitter contribution plus a fluctuating term containing
no trace of Boltzmann-like factors, but rather describing the way thermal equilibrium is reached in the late time limit. As
a consequence, and unlike the case of black holes, the identification of the dynamical surface gravity of a cosmological trapping
horizon as an effective temperature parameter seems lost, at least for our co-moving simplified detectors. The possibility
remains that a detector performing a proper motion along a Kodama trajectory may register something more, in which case the
horizon surface gravity would be associated more likely to vacuum correlations than to particle creation. |
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