Year: 2025
Type: article
Abstract: We show that the intensive variables associated with the outer and inner horizons of the Kerr–Newman black hole: absolute temperatures, angular velocities and electromagnetic potentials, obey a Gibbs–Duhem type relation, which is closely related, but however distinct, to the Smarr equation. Thus, analogously as in ordinary thermodynamics, $$T_{\pm }$$ T ± , $$\Omega _{\pm }$$ Ω ± and $$\Phi _{\pm }$$ Φ ± are not independent quantities. The relation also holds in the Kerr and Reissner–Nordström cases, while in the Schwarzschild case it is trivially fulfilled due to the zeroth law of black hole mechanics.
Institution: Universidad Nacional Autónoma de México
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,890
OpenAlex ID: W4414378305