A model detector for Hawking radiation from a Schwarzschild black hole

A model detector for field quanta is considered from the point of view of a quantum field theory defined in asymptotically stationary regions of the Kruskal manifold and from that of a theory restrictdd to a Schwarzschild coordinate patch. A spherical array of oscillators at a constant distance r from the black hole, harmonic with respect to their proper time, is coupled to spherically symmetric Schwarzschild-modes of the field. The system is quantized and the energy expectation value of the coupled harmonic oscillators in a state of the field representing Hawking radiation is calculated. The back-reaction to the field may be interpreted in two controversial ways: In terms of the quantum field theory restricted to Schwarzschild space-time there is merely some scattering of the Hawking radiation, whereas in the framework of Kruskal quantum field theory particle production occurs. (orig.)