Asymptotics of Killing horizons: A Characterization in de Sitter Spacetime

Abstract: We prove that (n + 1)-dimensional de Sitter spacetime is locally the unique $(Λ> 0)$-vacuum spacetime whose Killing horizons intersect the conformal boundary $\mathscr{I}$. The intersection occurs at the isolated essential zeros of the extension of the Killing vector field to $\mathscr{I}$. We then reconstruct all de Sitter Killing vector fields from their boundary value and obtain a characterization of those admitting a Killing horizon in terms of a conformal invariant $σ$: $σ<0$ characterizes non-degenerate bifurcate horizons, whereas $σ= 0$ yields degenerate non-bifurcate horizons. Finally, we derive an intrinsic, conformally invariant formula for the surface gravity of the horizons in de Sitter, $κ² = |σ|$.