Entropy and Mass Bounds of Kerr - de Sitter Spacetimes

We consider Kerr-de Sitter spacetimes and evaluate their mass, angular momentum and entropy according to the boundary counterterm prescription. We provide a physicall interpretation for angular velocity and angular momentum at future/past infinity. We show that the entropy of the four-dimensional Kerr-de Sitter spacetimes is less than of pure de Sitter spacetime in agreement to the entropic N-bound. Moreover, we show that maximal mass conjecture which states " any asymptotically de Sitter spacetime with mass greater than de Sitter has a cosmological singularity " is respected by asymptotically de Sitter spacetimes with rotation. We investigate the behavior of the c-function for the Kerr-de Sitter spacetimes and show that it is no longer isotropic. However an average of the c−function over the angular variables yields a renormalization group flow in agreement with the expansion of spacetime at future infinity.