General features of the thermalization of particle detectors and the Unruh effect

We study the thermalization of smeared particle detectors that couple locally to any operator in a quantum field theory curved spacetimes. show if state satisfies Kubo-Martin-Schwinger condition with inverse temperature $\ensuremath{\beta}$ respect detector's local notion time evolution, reasonable assumptions ensure probe thermalizes $1/\ensuremath{\beta}$ limit long interaction times. Our method also imposes bounds on size system its proper acceleration and spacetime curvature order accurately field. then apply this formalism uniformly accelerated detector probing Minkowski vacuum $CPT$ symmetric theory, Unruh temperature, independently it couples to. This exemplifies yet again robustness effect, even when arbitrary are used general operators theory.