https://doi.org/10.1140/epjc/s10052-022-10370-5
Regular Article - Theoretical Physics
On light surfaces in black hole thermodynamics
1
Research Centre for Theoretical Physics and Astrophysics, Institute of Physics, Silesian University in Opava, Bezručovo náměstí 13, 74601, Opava, Czech Republic
2
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, AP 70543, 04510, Mexico, DF, Mexico
3
Dipartimento di Fisica and ICRA, Università di Roma “La Sapienza”, 00185, Rome, Italy
Received:
2
March
2022
Accepted:
23
April
2022
Published online:
18
May
2022
We discuss the fundamentals of classical black hole (BH) thermodynamics in a new framework determined by light surfaces and their frequencies. This new approach allows us to study BH transitions inside the Kerr geometry. In the case of BHs, we introduce a new parametrization of the metric in terms of the maximum extractable rotational energy or, correspondingly, the irreducible mass, which is an alternative to the spin parametrization. It turns out that BH spacetimes with spins 
and 
show anomalies in the rotational energy extraction and surface gravity whereas the case 
is of particular relevance to study the variations of the horizon area. We find the general conditions under which BH transitions can occur and express them in terms of the masses of the initial and final states. This shows that BH transitions in the Kerr geometry are not arbitrary but depend on the relationship between the mass and spin of the initial and final states. From an observational point of view, we argue that near the BH poles it is possible to detect photon orbits with frequencies that characterize the light surfaces analyzed in this work.
© The Author(s) 2022
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