  The fermionic signature operator is constructed in Rindler space-time. It is
shown to be an unbounded self-adjoint operator on the Hilbert space of
solutions of the massive Dirac equation. In two-dimensional Rindler space-time,
we prove that the resulting fermionic projector state coincides with the
Fulling-Rindler vacuum. Moreover, the fermionic signature operator gives a
covariant construction of general thermal states, in particular of the Unruh
state. The fermionic signature operator is shown to be well-defined in
asymptotically Rindler space-times. In four-dimensional Rindler space-time, our
construction gives rise to new quantum states.
