Black hole evaporation in de Sitter space

We investigate the evaporation process of a Kerr-de Sitter black hole with Unruh-Hawking-like vacuum state, which is realistic state modelling originating from gravitational collapse. also compute greybody factors for gravitons, photons, and conformal-coupling massless scalar particles by using analytic solutions Teukolsky equation in background. It turns out that cosmological constant quenches amplification factor it approaches to zero towards critical point where Nariai extremal limits merge together. confirm even near point, superradiance gravitons more significant than photons particles. Angular momentum carried several times faster mass energy decreases. This means rapidly spins down nearly Schwarzschild-de before completely evaporates. time evolution Bekenstein-Hawking entropy. The total entropy horizon increases time, consistent generalized second law thermodynamics.