{
  "abstract": "We reconsider the Bardeen black hole surrounded by a Kiselev fluid, obtained by adding a Kiselev term to the Ayon-Beato-Garcia-Bardeen metric. Contrary to claims in the literature, the solution is regular at the origin only for $c=0$: for $c\\neq0$ curvature invariants diverge as $r\\to0$, and the spacetime is asymptotically de Sitter-like rather than flat, with a cosmological horizon $r_c$ for $0<c<c_N(q)$. We map the full $(q,c)$ domain of horizon structures in closed form, locating the extremal and Nariai-type boundaries and their cusp. Using the Ma-Zhao prescription for the mass-dependent nonlinear-electrodynamics source, we derive the corrected entropy and verify the extended first law and Smarr relation to machine precision by computer-algebra differentiation, not through the entropy's own definition. The heat capacity shows a single Davies-type divergence, located as a closed-form quartic and expanded analytically in $c$. In thermodynamic geometry, the Quevedo-metric curvature has a spurious second singularity generated by the entropy's integration constant and the non-uniqueness of its conformal factor; we isolate this artefact and show only the Davies-point divergence is physical. The Ruppeiner curvature, identically zero for pure Bardeen, becomes non-zero once $c\\neq0$. For the shadow, we compute the critical impact parameter $b_c(q,c,w)$ and show the nominal bound $c\\lesssim10^{-2}/M$ from the EHT image of Sagittarius A* is not self-consistent: the same $c$ places the cosmological horizon nine orders of magnitude closer than Earth's distance to Sgr A*, and the bound is fourteen orders of magnitude larger than $H_0/c$, the true cosmological dark-energy scale. We reinterpret the EHT constraint as bounding $c$ only near the horizon, not as an astrophysical or cosmological bound on the quintessence parameter.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.03801",
  "author_total": 1,
  "authors": [
    {
      "name": "Hoang Van Quyet"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1m1hz3bs8gd0y.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.03801",
  "fulltext_url": null,
  "id": "1m1hz3bs8gd0y",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.03801",
  "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",
      "3106|Black Holes and Theoretical Physics"
    ]
  ],
  "openalex": "W7220696400",
  "pdf_url": "https://arxiv.org/pdf/2610.03801",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1m1hz3bs8gd0y.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.03801",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.03801"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Thermodynamics, thermodynamic geometry, and the shadow of a Bardeen black hole surrounded by a Kiselev fluid: the role of regularity, asymptotics, and observational self-consistency",
  "title_text": "Thermodynamics, thermodynamic geometry, and the shadow of a Bardeen black hole surrounded by a Kiselev fluid: the role of regularity, asymptotics, and observational self-consistency",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/1m1hz3bs8gd0y",
  "venue": "arXiv",
  "versions": []
}