Phase transitions, shadows, and microstructure of Reissner-Nordstr"om-Anti-de-Sitter black holes from a geometrothermodynamic perspective
The study uses shadow thermodynamics and Geometrothermodynamics to analyze Reissner-Nordström-Anti-de Sitter (RN-AdS) black holes. It shows that the shadow radius links phase transitions to critical values of the curvature radius, which determines whether zero, one, or two second-order phase transitions happen. This geometrical approach reveals how the microstructure changes with black hole size.