Quasinormal Modes and Phase Structure of Regular $AdS$ Einstein-Gauss-Bonnet Black Holes

Abstract

In this paper, we present an exact regular black hole solution in Einstein-Gauss-Bonnet coupled with nonlinear matter fields. It is a generalization of a regular Einstein-Gauss-Bonnet black hole in $5D$ $AdS$ spacetime. The causal structure of the obtained solution identifies with Boulware-Deser black hole solution, except for the curvature singularity at the center. It incorporates the Boulware-Deser black holes in the absence of deviation parameters. We also study the thermodynamic properties of the solution that satisfies a modified first law of thermodynamics. Furthermore, we discuss the stability of the obtained black hole solution and, in this regard, a double phase transition occurs. Within context, we find that phase transition exists at the point where the heat capacity diverges and, incidentally, the temperature attains the maximum value. We discuss the fluid nature of the black hole also exhibiting critical points. The quasinormal modes of the black hole solution and their dependencies on Gauss-Bonnet coupling and deviation parameters are also analysed in terms of null geodesics.