Heat capacities and thermodynamic geometry in deformed Jackiw-Teitelboim gravity

We study the thermodynamics of charged AdS black holes in deformed Jackiw-Teitelboim (dJT) gravity and their phase transitions. In this regard, we will find some critical values for the temperature, entropy and charge of the corresponding black holes. We also compute the heat capacities, expansion coefficient and isothermal compressibility as thermodynamic response functions and study their behaviour at the critical points. We employ different formalisms to investigate thermodynamic geometry, such as Weinhold, Ruppeiner and new thermodynamic geometry and analyze the singularities of the thermodynamic curvature in this context. These singularities are correspond to the divergences of the response functions and indicate the critical points of phase transitions.