Central charge and black hole entropy for regular extremal black-bounce spacetimes
Abstract
The Bekenstein-Hawking entropy, proportional to one quarter of the horizon area, is fundamental in black hole thermodynamics and can also be understood via the AdS/CFT correspondence, such as the 3D BTZ black hole and 2D CFT. In this work, we adopt the Kerr/CFT approach to analyze the central charge and black hole entropy for regular extremal black-bounce spacetimes, including the counterparts of the Kerr, Kerr-Newman, and Reissner-Nordström black holes. These spacetimes are free of curvature singularities at r=0. We derive the near horizon geometries of these spacetimes and find that they exhibit enhanced symmetry, namely SL(2,ℝ)× U(1) or SL(2,ℝ) × SO(3). By imposing appropriate boundary conditions, we analyze their asymptotic symmetry groups, which contain diffeomorphisms as well as the U(1)gauge symmetry arising from the electromagnetic field. We then extract the central charge from the charge algebra and evaluate the left-moving temperature of the Frolov-Thorne vacuum. It is worth emphasizing that in the black-bounce Kerr-Newman case, the central charge from the electromagnetic contribution vanishes. Furthermore, in the black-bounce Reissner-Nordström case, we uplift the 4D geometry to a 5D configuration by incorporating a U(1) gauge fiber. Our results show that the microscopic entropy calculated from the Cardy formula is consistent with the Bekenstein-Hawking entropy. This agreement suggests that the Kerr/CFT approach remains valid for certain regular spacetimes without curvature singularities, thereby providing a microscopic statistical understanding of black hole entropy.
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BibTeX
@misc{ye2026central,
title = {{Central charge and black hole entropy for regular extremal black-bounce spacetimes}},
author = {Xu Ye and Shan-Ping Wu and Yu-Kun Zhang and Shao-Wen Wei},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.18028},
eprint = {2609.18028},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.18028},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Central charge and black hole entropy for regular extremal black-bounce spacetimes
AU - Xu Ye
AU - Shan-Ping Wu
AU - Yu-Kun Zhang
AU - Shao-Wen Wei
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.18028
UR - https://arxiv.org/abs/2609.18028
AB - The Bekenstein-Hawking entropy, proportional to one quarter of the horizon area, is fundamental in black hole thermodynamics and can also be understood via the AdS/CFT correspondence, such as the 3D BTZ black hole and 2D CFT. In this work, we adopt the Kerr/CFT approach to analyze the central charge and black hole entropy for regular extremal black-bounce spacetimes, including the counterparts of the Kerr, Kerr-Newman, and Reissner-Nordström black holes. These spacetimes are free of curvature singularities at r=0. We derive the near horizon geometries of these spacetimes and find that they exhibit enhanced symmetry, namely SL(2,ℝ)× U(1) or SL(2,ℝ) × SO(3). By imposing appropriate boundary conditions, we analyze their asymptotic symmetry groups, which contain diffeomorphisms as well as the U(1)_gauge symmetry arising from the electromagnetic field. We then extract the central charge from the charge algebra and evaluate the left-moving temperature of the Frolov-Thorne vacuum. It is worth emphasizing that in the black-bounce Kerr-Newman case, the central charge from the electromagnetic contribution vanishes. Furthermore, in the black-bounce Reissner-Nordström case, we uplift the 4D geometry to a 5D configuration by incorporating a U(1) gauge fiber. Our results show that the microscopic entropy calculated from the Cardy formula is consistent with the Bekenstein-Hawking entropy. This agreement suggests that the Kerr/CFT approach remains valid for certain regular spacetimes without curvature singularities, thereby providing a microscopic statistical understanding of black hole entropy.
ER -