{
  "abstract": "The diversity of Type I AGNs can be organized along the Quasar Main Sequence (MS), a powerful framework primarily driven by the accretion rate and defined in the optical plane by the FWHM of $\\mathrm{Hβ}$ and the Fe II strength ($R_{\\rm FeII}$). Previous studies suggested that the UV Fe III evolves along this MS. However, a systematic analysis is still missing. We aim to characterize the UV Fe III emission across the MS, assess its potential as a tracer, and investigate how its properties depend on the conditions of the emitting gas. We analyzed the UV iron emission in 69 low-$z$ $(z \\lesssim 1)$ AGNs observed with the Hubble Space Telescope. We fitted the 1700-2200 Angstrom range and investigated the main correlations using principal component analysis. We complemented with $\\tt{CLOUDY}$ photoionization simulations to explore the dependence of the iron emission on gas density, ionization parameter, metallicity, microturbulence, column density, and spectral energy distribution. We find a positive correlation between the strengths of the UV iron emission and the optical $\\mathrm{R_{FeII}}$ parameter. With this, we define a UV MS diagram using the FWHM of $\\mathrm{Al III\\,\\lambda1860}$ and the equivalent width of $\\mathrm{Fe III}$ + $\\mathrm{Fe II}$. $\\tt{CLOUDY}$ simulations support this result, predicting stronger Fe III emission at high $\\mathrm{R_{FeII}}$. Additionally, we found object-to-object variations in the $\\mathrm{Fe III}$ multiplets. Our results indicate that UV Fe III emission and $\\mathrm{Al III}\\,λ1860$ can serve as proxies for optical Fe II and $\\mathrm{Hβ}$, extending the Quasar MS into the UV domain. The variations in the Fe III multiplets demonstrate that a single template may not represent all quasars. Thus, characterizing the Fe III emission and its dependence on physical conditions is essential for improving the modeling of UV AGN spectra.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.33339",
  "author_total": 6,
  "authors": [
    {
      "name": "Diego Martínez Collipal"
    },
    {
      "name": "Mary Loli Martínez-Aldama"
    },
    {
      "name": "Ashwani Pandey"
    },
    {
      "name": "Paola Marziani"
    },
    {
      "name": "Swayamtrupta Panda"
    },
    {
      "name": "Marco Cárdenas"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/exmfz393dsew3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.33339",
  "fulltext_url": null,
  "id": "exmfz393dsew3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.33339",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7223923409",
  "pdf_url": "https://arxiv.org/pdf/2610.33339",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/exmfz393dsew3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2610.33339",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.33339"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Exploring the UV Fe III Emission along the Quasar Main Sequence",
  "title_text": "Exploring the UV Fe III Emission along the Quasar Main Sequence",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/exmfz393dsew3",
  "venue": "arXiv",
  "versions": []
}