Classical and Quantum Reissner-Nordstr\"om Black Hole Thermodynamics and first order Phase Transition

TL;DR

This paper analyzes the thermodynamics and phase transitions of classical and quantum Reissner-Nordström black holes, revealing a first order phase transition at a critical temperature and discussing the evaporation process leading to a stable remnant.

Contribution

It introduces a detailed thermodynamic analysis of CRNBH and QRNBH, identifying a first order phase transition and the properties of black hole remnants after evaporation.

Findings

First order phase transition at critical temperature $T_c$.

Black hole evaporation halts, leaving a stable remnant with mass $|e|$.

Temperature and luminosity vanish for the remnant, addressing information loss.

Abstract

First we consider CRNBH metric which is obtained by solving Einstein-Maxwell metric equation for a point electric charge $e$ inside of a spherical static body with mass $M$. It has 2 interior and exterior horizons. Using Bekenestein-Hawking entropy theorem we calculate interior and exterior entropy, temperature, Gibbs free energy and heat capacity at constant electric charge. We calculate first derivative of the Gibbs free energy with respect to temperature which become a singular function having a singularity at critical point with corresponding temperature $T_c=\frac{1}{24\pi \sqrt{3}|e|}.$ Hence we clime first order phase transition is happened there. Temperature same as Gibbs free energy takes absolutely positive (negative) values on the exterior (interior) horizon. The Gibbs free energy takes two different positive values synchronously for $0<T<T_c$ but not for negative values which means the system is made from two subsystem. For negative temperatures entropy reaches to zero value at $T\to-\infty$ and so takes Bose-Einstein condensation single state. Entropy increases monotonically in case $0<T<T_c$. Regarding results of the work presented at Ref. \citep{Bob01} we calculate again the mentioned thermodynamical variables for remnant stable final state of evaporating QRNBH and obtained results same as one in case of the CRNBH. Finally, we solve mass loss equation of QRNBH against advance Eddington-Finkelstein time coordinate and derive luminosity function. We obtain switching off of QRNBH evaporation before than the mass completely vanishes. It reaches to a could Lukewarm type of RN black hole which its final remnant mass is $m_{final}=|e|$ in geometrical units. Its temperature and luminosity vanish but not in Schwarzschild case of evaporation. Our calculations can be takes some acceptable statements about information loss paradox .