Thermodynamic analysis of a compact object in Rastall-Rainbow gravity

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Hauptverfasser: Eslamzadeh, Sareh, Soroushfar, Saheb
Format: Preprint
Veröffentlicht: 2025
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author Eslamzadeh, Sareh
Soroushfar, Saheb
author_facet Eslamzadeh, Sareh
Soroushfar, Saheb
contents In this paper, we investigate the thermodynamic behavior of a horizonless compact object within the framework of Rastall-Rainbow (RR) gravity. Working with local shell thermodynamics for gravastar and an exterior fiducial temperature, we show that the RR modification bends temperature to produce two extrema and a stable mass remnant at zero temperature. We show that the gravastar's shell entropy is smaller than that of a comparable black hole, and that RR modifications introduce a logarithmic correction which contributes to specific heat positivity and a smoother free energy landscape of small gravastars. A Central finding of this work is that, from heat capacity and Helmholtz free energy analyses, we uncover small, middle, and large branches and demonstrate that unlike Rainbow modified black holes, the small RR gravastar is both locally and globally favored over hot curved space. At the parameter level, both Rastall and Rainbow play distinct roles. Increasing the Rastall parameter, by strengthening matter-curvature coupling, adjusts the redshift between the shell and the exterior, shifts the temperature maximum to higher values at larger masses, and narrows the unstable window. In contrast, increasing the Rainbow parameter enhances energy dependent UV suppression and bends the temperature in lower values at larger masses. Altogether, these results highlight a controlled route to thermodynamic stabilization and the emergence of a stable remnant in horizonless compact objects within RR gravity.
format Preprint
id arxiv_https___arxiv_org_abs_2512_13471
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Thermodynamic analysis of a compact object in Rastall-Rainbow gravity
Eslamzadeh, Sareh
Soroushfar, Saheb
General Relativity and Quantum Cosmology
High Energy Physics - Theory
In this paper, we investigate the thermodynamic behavior of a horizonless compact object within the framework of Rastall-Rainbow (RR) gravity. Working with local shell thermodynamics for gravastar and an exterior fiducial temperature, we show that the RR modification bends temperature to produce two extrema and a stable mass remnant at zero temperature. We show that the gravastar's shell entropy is smaller than that of a comparable black hole, and that RR modifications introduce a logarithmic correction which contributes to specific heat positivity and a smoother free energy landscape of small gravastars. A Central finding of this work is that, from heat capacity and Helmholtz free energy analyses, we uncover small, middle, and large branches and demonstrate that unlike Rainbow modified black holes, the small RR gravastar is both locally and globally favored over hot curved space. At the parameter level, both Rastall and Rainbow play distinct roles. Increasing the Rastall parameter, by strengthening matter-curvature coupling, adjusts the redshift between the shell and the exterior, shifts the temperature maximum to higher values at larger masses, and narrows the unstable window. In contrast, increasing the Rainbow parameter enhances energy dependent UV suppression and bends the temperature in lower values at larger masses. Altogether, these results highlight a controlled route to thermodynamic stabilization and the emergence of a stable remnant in horizonless compact objects within RR gravity.
title Thermodynamic analysis of a compact object in Rastall-Rainbow gravity
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2512.13471