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arXiv · 2507.14105

Apparent Horizons Associated with Dynamical Black Hole Entropy

Hideo Furugori·Kanji Nishii·Daisuke Yoshida·Kaho Yoshimura
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Abstract

We define entropic marginally outer trapped surfaces (E-MOTSs) as a generalization of apparent horizons. We then show that, under first-order perturbations around a stationary black hole, the dynamical black hole entropy proposed by Hollands, Wald, and Zhang, defined on a background Killing horizon, can be expressed as the Wall entropy evaluated on an E-MOTS associated with it. Our result ensures that the Hollands-Wald-Zhang entropy reduces to the standard Wald entropy in each stationary regime of a dynamical black hole, thereby reinforcing the robustness of the dynamical entropy formulation.

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Hideo Furugori, Kanji Nishii, Daisuke Yoshida, Kaho Yoshimura. 2025-07-18. Apparent Horizons Associated with Dynamical Black Hole Entropy. https://doi.org/10.1103/f2t6-7t61

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