Bardeen-like regular black holes in $5D$ Einstein-Gauss-Bonnet gravity (1911.11054v1)

Abstract: We find an exact spherically symmetric regular Bardeen-like solutions by considering the coupling between Einstein-Gauss-Bonnet theory and nonlinear electrodynamics (NED) in five-dimensional spacetime. These solutions, with an additional parameter $g$ apart from the mass $M$, represent black holes with Cauchy and event horizons, extremal black holes with degenerate horizons or no black holes in the absence of the horizons, and encompasses as a special case Boulware-Deser black holes which can be recovered in the absence of magnetic charge ($g=0$). Owing to the NED corrected black hole, the thermodynamic quantities have also been modified and we have obtained exact analytical expressions for the thermodynamical quantities such the Hawking temperature $T_+$, the entropy $S_+$, the specific heat $C_+$, and the Gibbs free energy $F_+$. The heat capacity diverges at a critical radius $r=r_C$, where incidentally the temperature has a maximum, and the Hawking-Page transitions even in absence of the cosmological term. The thermal evaporation process leads to eternal remnants for sufficiently small black holes and evaporates to a thermodynamic stable extremel black hole remnants with vanishing temperature. The heat capacity becomes positive $C_+ > 0$ for $r_+ < r_C$ allowing black hole to become thermodynamically stable, in addition the smaller black holes are globally stable with positive heat capacity $C_+ > 0$ and negative free energy $F_+<0$. The entropy $ S $ of a 5D Bardeen black hole is not longer a quarter of the horizon area $A$, i.e., $S \neq A/4$.