Hawking tunneling radiation with thermodynamic pressure

TL;DR

This work studies Hawking radiation from Schwarzschild-AdS black holes in an extended phase space where the cosmological constant is dynamical and interpreted as thermodynamic pressure $P$. Mass is treated as enthalpy $\mathcal{H}=U+PV$, and the thermodynamic volume is $V=\frac{4}{3}\pi r_H^3$, with the first law $dM=TdS+VdP$. Using the null geodesic (tunneling) method with self-gravitation, the authors compute the imaginary part of the action and obtain a tunneling rate $\Gamma\propto e^{\Delta S_{BH}}$, where $\Delta S_{BH}=S_{BH}(M-\omega',P-p')-S_{BH}(M,P)$. The resulting radiation spectrum is non-thermal, consistent with unitary evolution, and the analysis connects the tunneling picture to the extended first law via $d(M-\omega')-V' d(P-p')$. The findings extend Hawking tunneling to the extended phase space and highlight how $P$ and $V$ influence black-hole radiation, providing a unified framework for quantum gravitational effects in black hole thermodynamics and guiding future investigations to other black hole solutions.

Abstract

Hawking radiation elucidates black holes as quantum thermodynamic systems, thereby establishing a conceptual bridge between general relativity and quantum mechanics through particle emission phenomena. While conventional theoretical frameworks predominantly focus on classical spacetime configurations, recent advancements in Extended Phase Space thermodynamics have redefined cosmological parameters (such as the $Λ$-term) as dynamic variables. Notably, the thermodynamics of Anti-de Sitter (AdS) black holes has been successfully extended to incorporate thermodynamic pressure $P$. Within this extended phase space framework, although numerous intriguing physical phenomena have been identified, the tunneling mechanism of particles incorporating pressure and volume remains unexplored. This study investigates Hawking radiation through particle tunneling in Schwarzschild Anti-de Sitter black holes within the extended phase space, where the thermodynamic pressure $P$ is introduced via a dynamic cosmological constant $Λ$. By employing semi-classical tunneling calculations with self-gravitation corrections, we demonstrate that emission probabilities exhibit a direct correlation with variations in Bekenstein-Hawking entropy. Significantly, the radiation spectrum deviates from pure thermality, aligning with unitary quantum evolution while maintaining consistency with standard phase space results. Moreover, through thermodynamic analysis, we have verified that the emission rate of particles is related to the difference in Bekenstein-Hawking entropy of the emitted particles before and after they tunnel through the potential barrier. These findings establish particle tunneling as a unified probe of quantum gravitational effects in black hole thermodynamics.