Universality of the quantum energy flux at the inner horizon of asymptotically de Sitter black holes

Recently, it was found that the energy flux of a free scalar quantum field on a Reissner-Nordström-de Sitter spacetime has a quadratic divergence towards the inner horizon of the black hole. Moreover, the leading divergence was found to be state independent as long as the spectral gap of the wave equation on the spacetime is sufficiently large. In this work, we show that the latter result can be extended to all subextremal Reissner-Nordström-de Sitter and subextremal Kerr-de Sitter spacetimes with a positive spectral gap.