Radiating black holes in the novel 4D Einstein–Gauss–Bonnet gravity

Abstract

Recently Glavan and Lin (2020) formulated a novel Einstein–Gauss–Bonnet gravity in which the Gauss–Bonnet coupling has been rescaled as α∕(D−4) and the 4D theory is defined as the limit D→4, which preserves the number degrees of freedom thereby free from the Ostrogradsky instability. We present exact spherically symmetric nonstatic null dust solutions in the novel 4D Einstein–Gauss–Bonnet gravity that bypasses the Lovelock theorem. Our solution represents radiating black holes and regains, in the limit α→0, the famous Vaidya black hole of general relativity (GR). We discuss the horizon structure of black hole solutions to find that the three horizon-like loci that characterizes its structure, viz. AH, EH and TLS have the relationship rEH<rAH=rTLS. The charged radiating black holes in the theory, generalizing Bonnor–Vaidya black holes, are also considered. In particular our results, in the limit α→0, reduced exactly to vis-à-vis 4D black holes of GR.