{
  "abstract": "We study quasinormal modes (QNMs) of a minimally coupled massless scalar field on four-dimensional Schwarzschild–anti-de Sitter (SAdS) black holes using a Chebyshev spectral method. After compactifying the exterior domain, the radial problem is formulated as a quadratic matrix pencil in the dimensionless frequency. For the standard Dirichlet, or vanishing-field, boundary condition at the conformal AdS boundary, we reproduce the known scalar spectra across small, intermediate, and large black holes, including long overtone sequences and the expected approach to pure-AdS normal modes in the small black hole limit. We also impose a one-parameter relation between the slow and fast asymptotic coefficients. For a massless scalar in four dimensions, the slow branch lies outside the standard finite canonical energy domain. Because we neither construct a renormalized variational principle nor prove well-posedness of an evolution containing this branch, we present only the formal spectrum of the deformed radial problem. Each non-Dirichlet value examined yields an additional eigenvalue with positive imaginary part and hence, an exponentially growing separated formal mode. This does not establish a physical instability of the standard scalar theory. The interpolation parameter is representation-dependent. In a black-hole-independent conformal coordinate, the corresponding response coupling scales with the cube of the dimensionless horizon radius, so equal intermediate parameter values for different black-hole sizes do not represent the same boundary coupling.",
  "abstract_shown": true,
  "affiliations": [
    "Khalifa University of Science and Technology",
    "University of Johannesburg"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Davide Batic",
      "orcid": "0000-0002-7619-4900"
    },
    {
      "affs": [
        1
      ],
      "name": "Alan S. Cornell",
      "orcid": "0000-0003-1896-4628"
    },
    {
      "affs": [
        0
      ],
      "name": "Denys Dutykh",
      "orcid": "0000-0001-5247-2788"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1bbmxbdndvsjv.bib",
  "cited_by": 0,
  "doi": "10.1140/epjc/s10052-026-16449-7",
  "fulltext_url": null,
  "id": "1bbmxbdndvsjv",
  "issns": [
    "1434-6052",
    "1434-6044"
  ],
  "landing_url": "https://link.springer.com/article/10.1140/epjc/s10052-026-16449-7",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0",
  "metadata_licence": null,
  "native_subjects": [
    [
      "feed-journal",
      "physics/high-energy"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16449-7.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-29",
  "publisher": "Springer Science and Business Media LLC",
  "ris": "https://research.draconitic.com/paper/1bbmxbdndvsjv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:18Z",
      "native_id": "10.1140/epjc/s10052-026-16449-7",
      "source": "feed-springer",
      "url": "https://link.springer.com/article/10.1140/epjc/s10052-026-16449-7"
    },
    {
      "first_seen": "2026-10-30T12:18:04Z",
      "native_id": "10.1140/epjc/s10052-026-16449-7",
      "source": "crossref",
      "url": "https://link.springer.com/article/10.1140/epjc/s10052-026-16449-7"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "feed-journal:physics/high-energy",
      "subfield": "high-energy"
    }
  ],
  "title": "Scalar quasinormal modes of Schwarzschild–anti-de Sitter black holes: spectral analysis and a formal coefficient deformation",
  "title_text": "Scalar quasinormal modes of Schwarzschild–anti-de Sitter black holes: spectral analysis and a formal coefficient deformation",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T00:20:43Z",
  "url": "https://research.draconitic.com/paper/1bbmxbdndvsjv",
  "venue": "The European Physical Journal C",
  "versions": []
}