Renormalized stress tensor in Kerr space-time: General results - art. no. 084018

We derive constraints on the form of the renormalized stress tensor for sta tes on Kerr space-time based on general physical principles: symmetry, the conservation equations, the trace anomaly and regularity on (sections of) t he event horizon. This is then applied to the physical vacua of interest. W e introduce the concept of past and future Boulware vacua and discuss the n on-existence of a state empty at both F- and J(+). By calculating the stres s tensor for the Unruh vacuum at the event horizon and at infinity, we are able to check our earlier conditions. We also discuss the difficulties of d efining a state equivalent to the Hartle-Hawking vacuum and comment on the properties of two candidates for this state.