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Bibliographic Details
Main Author: Torres, Ramon
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.11422
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author Torres, Ramon
author_facet Torres, Ramon
contents We formulate an analogue transverse first law for general closed marginally trapped surfaces in arbitrary spacetimes. The construction is intrinsically quasi-local and is attached directly to an individual marginally trapped surface, rather than to a preferred horizon worldtube. Taking the Hawking energy as the internal energy and an invariant effective surface gravity associated with the marginally trapped surface as the quantity controlling the thermal term, we derive a balance law in which the variation of energy splits into a generalized heat contribution and a total work contribution. In this way, the resulting law provides a codimension-two, transverse counterpart to existing horizon-based formulations of black-hole thermodynamics. We show that the formalism reproduces the expected results for round spheres in spherically symmetric spacetimes. We then examine semiclassical equilibrium and evaporating regimes, and extend the analysis to non-spherically symmetric marginally trapped surfaces in Kerr. These examples indicate that the framework remains applicable in situations where a horizon-based treatment is either nonunique or technically cumbersome, and suggest that closed marginally trapped surfaces provide a natural arena for a genuinely quasi-local thermodynamics of black holes.
format Preprint
id arxiv_https___arxiv_org_abs_2603_11422
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An analogue first law for general closed marginally trapped surfaces
Torres, Ramon
General Relativity and Quantum Cosmology
High Energy Physics - Theory
We formulate an analogue transverse first law for general closed marginally trapped surfaces in arbitrary spacetimes. The construction is intrinsically quasi-local and is attached directly to an individual marginally trapped surface, rather than to a preferred horizon worldtube. Taking the Hawking energy as the internal energy and an invariant effective surface gravity associated with the marginally trapped surface as the quantity controlling the thermal term, we derive a balance law in which the variation of energy splits into a generalized heat contribution and a total work contribution. In this way, the resulting law provides a codimension-two, transverse counterpart to existing horizon-based formulations of black-hole thermodynamics. We show that the formalism reproduces the expected results for round spheres in spherically symmetric spacetimes. We then examine semiclassical equilibrium and evaporating regimes, and extend the analysis to non-spherically symmetric marginally trapped surfaces in Kerr. These examples indicate that the framework remains applicable in situations where a horizon-based treatment is either nonunique or technically cumbersome, and suggest that closed marginally trapped surfaces provide a natural arena for a genuinely quasi-local thermodynamics of black holes.
title An analogue first law for general closed marginally trapped surfaces
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2603.11422