Static black hole in minimal Horndeski gravity with Maxwell and Yang-Mills fields and some aspects of its thermodynamics

In this work we obtain a static spherically symmetric charged black hole solution in the framework of minimal Horndeski gravity with additional Maxwell and Yang-Mills fields. The obtained solution is examined, in particular its asymptotics are studied. Thermodynamics of the black hole is investigated, namely we use an effective surface gravity to derive black hole temperature. To obtain the first law of black hole thermodynamics the Wald method is applied. We also use the extended thermodynamics approach, namely it allows us to derive the Smarr relation, Gibbs free energy and the thermal equation of state. The study of thermal values in the extended space shows rich phase behaviour, in particular domain where the first order phase transition takes place and the critical point with the second order phase transition. We also study thermal behaviour near the critical point, obtain critical exponents and analyse the Ehrenfest's equations at the critical point. Finally, we calculate the Prigogine-Defay ratio confirming the conclusion about the second order phase transition at the critical point.Comment: 27 pages + references, 7 figure