{
  "abstract": "The Seyfert 1 galaxy H 0557$-$385 (z = 0.034) has long been classified as radio-quiet on the basis of its radio-to-optical flux ratio, yet its radio properties are physically inconsistent with this designation. We present a broadband ($0.076 - 258.8$ GHz) radio spectral analysis combining new Australia Telescope Compact Array (ATCA) observations with archival Murchison Widefield Array (MWA), Australian Square Kilometre Array Pathfinder (ASKAP) and Atacama Large Millimeter/submillimeter Array (ALMA) data. The spectrum requires a two-component model: a compact, self-absorbed component with a stratified gigahertz-peaked (GPS)/high-frequency-peaked (HFP) spectral shape (turnover at $9.4^{+0.6}_{-0.5}$ GHz), superposed on an extended, optically thin power-law lobe ($α_{\\rm pl} = -0.78$) that dominates below ~1.6 GHz. The derived parameters $-$ a source size of ~15 pc, an equipartition magnetic field of 2.8 mG, a synchrotron age of $\\lesssim1.8\\times10^{3}$ yr, and a time-averaged jet power of ${\\sim}5\\times10^{41}$ $-$ $5\\times10^{44}$ erg s$^{-1}$ $-$ are characteristic of compact steep-spectrum and GPS young radio galaxies, not of canonical radio-quiet AGN. The two-component structure admits two interpretations that the present data cannot distinguish: the extended emission may be the growing lobe of a genuinely young, expanding radio galaxy, or relic plasma from an earlier episode of a transient or recurrent jet. Under either, H 0557$-$385 is better understood as an intermediate object: optically a Seyfert, but with the radio-physical properties of a newly ignited or recently re-triggered radio galaxy. It is therefore a candidate missing link between radio-quiet AGN and large-scale radio galaxies. Distinguishing these scenarios will require high-resolution imaging and multi-epoch monitoring",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.03818",
  "author_total": 12,
  "authors": [
    {
      "name": "J. Chauhan"
    },
    {
      "name": "T. D. Russell"
    },
    {
      "name": "A. Lohfink"
    },
    {
      "name": "M. Bottcher"
    },
    {
      "name": "F. Panessa"
    },
    {
      "name": "R. L. C. Starling"
    },
    {
      "name": "K. Nyland"
    },
    {
      "name": "C. Done"
    },
    {
      "name": "S. Chattopadhyay"
    },
    {
      "name": "T. Ghosh"
    },
    {
      "name": "R. Misra"
    },
    {
      "name": "M. Del Santo"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/agscm4hv7ym0j.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.03818",
  "fulltext_url": null,
  "id": "agscm4hv7ym0j",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.03818",
  "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",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.03818",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/agscm4hv7ym0j.ris",
  "sources": [
    {
      "first_seen": "2026-11-04T15:21:25Z",
      "native_id": "2611.03818",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.03818"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "H 0557$-$385: A Candidate Missing Link Between Radio-Quiet Seyferts and Young Radio Galaxies",
  "title_text": "H 0557−385: A Candidate Missing Link Between Radio-Quiet Seyferts and Young Radio Galaxies",
  "type": "preprint",
  "updated_at": "2026-11-06T18:21:01Z",
  "url": "https://research.draconitic.com/paper/agscm4hv7ym0j",
  "venue": "arXiv",
  "versions": []
}