paper

On the massive wave equation on slowly rotating Kerr-AdS spacetimes

arXiv:0902.0973 · doi:10.1007/s00220-009-0935-9

Abstract

The massive wave equation is studied on a fixed Kerr-anti de Sitter background . We first prove that in the Schwarzschild case (a=0), remains uniformly bounded on the black hole exterior provided that , i.e. the Breitenlohner-Freedman bound holds. Our proof is based on vectorfield multipliers and commutators: The usual energy current arising from the timelike Killing vector field (which fails to be non-negative pointwise) is shown to be non-negative with the help of a Hardy inequality after integration over a spacelike slice. In addition to , we construct a vectorfield whose energy identity captures the redshift producing good estimates close to the horizon. The argument is finally generalized to slowly rotating Kerr-AdS backgrounds. This is achieved by replacing the Killing vectorfield with for an appropriate , which is also Killing and--in contrast to the asymptotically flat case--everywhere causal on the black hole exterior. The separability properties of the wave equation on Kerr-AdS are not used. As a consequence, the theorem also applies to spacetimes sufficiently close to the Kerr-AdS spacetime, as long as they admit a causal Killing field which is null on the horizon.

1 figure; typos corrected, references added, introduction revised; to appear in CMP

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