Particle creation by de Sitter black holes revisited

Understand

Creation of thermal distribution of particles by a black hole is independent of the detail of gravitational collapse, making the construction of the eternal horizons suffice to address the problem in asymptotically flat spacetimes.

• For eternal de Sitter black holes however, earlier studies have shown the existence of both thermal and non-thermal particle creation, originating from the non-trivial causal structure of these spacetimes.
• Keeping this in mind we consider this problem in the context of a quasistationary gravitational collapse occurring in a $(3+1)$-dimensional eternal de Sitter, settling down to a Schwarzschild- or Kerr-de Sitter spacetime and consider a massless minimally coupled scalar field.
• There is a unique choice of physically meaningful `in' vacuum here, defined with respect to the positive frequency cosmological Kruskal modes localised on the past cosmological horizon ${\cal C^-}$, at the onset of the collapse.