{
  "abstract": "We investigate the cosmological dynamics and thermodynamic properties of a viscous variable generalized Chaplygin gas (VVGCG) model in a spatially flat Friedmann--Lema^ıtre--Robertson--Walker universe, described by $P=-B/ρ^α$, where $B=B_0V^{n/3}$. The model includes a bulk-viscous pressure $Π=-3ξH$, with $ξ=ξ_0ρ^{1/2}$. We find that the physically viable branch corresponds to $ξ_0<0$, for which the positive viscous pressure dominates at early times, producing decelerated expansion. As the volume increases, the effective pressure changes sign at a finite volume $V_c$, while the transition to acceleration occurs at a larger volume $V_f$. At large volume, the equation-of-state parameter approaches a phantom-like regime for $n<0$. A detailed thermodynamic analysis of the thermal and caloric equations of state, entropy, heat capacity, and isothermal and adiabatic stability shows that the stability conditions and $c_V>0$ are simultaneously satisfied for $n<0$ and $ξ_0<0$. The entropy vanishes as $T\\rightarrow0$, consistent with the third law, while the model admits a finite minimum volume and corresponding maximum temperature. Thermodynamic consistency is further verified through the fundamental thermodynamic identity. The framework also contains several existing Chaplygin-gas models as special cases. Constraints from the Hubble-57 data yield $α=0.0024$, $n=-0.0182$, and $ξ_0=-0.0015$, consistent with the thermodynamically stable parameter region. Thus, the VVGCG model provides a consistent description of cosmic evolution from an early decelerating phase to late-time phantom-like acceleration while remaining thermodynamically stable throughout the evolution.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.05361",
  "author_total": 3,
  "authors": [
    {
      "name": "D. Panigrahi"
    },
    {
      "name": "K. Kanjilal"
    },
    {
      "name": "Saibal Ray"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/73vdff27wnqfc.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.05361",
  "fulltext_url": null,
  "id": "73vdff27wnqfc",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.05361",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7220740042",
  "pdf_url": "https://arxiv.org/pdf/2610.05361",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/73vdff27wnqfc.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.05361",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.05361"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Thermodynamic Stability of a Viscous Variable Generalised Chaplygin Gas",
  "title_text": "Thermodynamic Stability of a Viscous Variable Generalised Chaplygin Gas",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/73vdff27wnqfc",
  "venue": "arXiv",
  "versions": []
}