H. Narnhofer, I. Peter, W. Thirring
How Hot Is the de Sitter Space? 
(40K, LaTeX)

ABSTRACT.  We show that the unique invariant locally Minkowskian state 
of quantum fields in de Sitter space $M$ has for an observer
moving along with a Killing vector field a temperature
$\frac{1}{2\pi} \sqrt{\frac{1}{R^2} + |a|^2}$ where $R$ is the radius
of $M$ and $a$ his acceleration. States with another temperature
cannot be locally Minkowskian all over $M$.