Black holes and the positive cosmological constant

TL;DR

This paper explores black hole spacetimes with a positive cosmological constant, analyzing horizons, no-hair theorems, cosmic strings, and particle creation effects in such cosmological settings.

Contribution

It provides a general criterion for the existence of cosmological horizons and investigates classical and quantum phenomena in black holes within de Sitter space.

Findings

Established a criterion for cosmological horizon existence

Analyzed no-hair theorems in de Sitter black holes

Calculated particle creation by horizons in Schwarzschild-de Sitter spacetime

Abstract

We address some aspects of black hole spacetimes endowed with a positive cosmological constant, i.e. black holes located inside a cosmological event horizon. First we establish a general criterion for existence of cosmological event horizons. Using the geometrical set up built for this, we study classical black hole no hair theorems for both static and stationary axisymmetric spacetimes. We discuss cosmic Nielsen-Olesen strings as hair in Schwarzschild-de Sitter spacetime. We also give a general calculation for particle creation by a Killing horizon using complex path analysis and using this we study particle creation in Schwarzschild-de Sitter spacetime by both black hole and the cosmological event horizons.