{
  "abstract": "We report spectroscopic observations of a remarkable QSO, J115724.80-000455.56 at $z=0.287$ from the Dark Energy Spectroscopic Instrument (DESI) survey. This QSO exhibits variability in its hydrogen Balmer absorption over a time interval of 10 months in the observed frame between 2021 and 2022. The observed Balmer absorption can be decomposed into two components with distinct kinematics: a non-varying, \"stationary\" component and a varying, \"dynamic\" component. Both absorbers have gas column densities of $N_{\\rm H}\\sim 10^{22}~{\\rm cm^{-2}}$ and likely have densities of $n_{\\rm H}\\gtrsim 10^{8}~{\\rm cm^{-3}}$. We inferred small effective physical sizes of $\\lesssim 10^{-3}$ pc for the absorbers, which, together with the time variability, suggests that the absorption occurs in the broad-line region (BLR). The reshifted centroid velocities of both absorbers imply an inflow, where the inferred mass inflow rate is comparable to the single-epoch mass accretion rate of this QSO. The 2022 epoch of this QSO further reveals a 10% change in the column density over 2 months, indicating the gas inflow might be continuous. We also obtained new X-ray observations using the $\\it Einstein~Probe$, which reveals an X-ray-to-bolometric luminosity ratio significantly below the general AGN population. The X-ray weakness is consistent with strong gas obscuration with $N_{\\rm H}= 4.0^{+ 1.6}_{- 1.5}\\times10^{23}~{\\rm cm^{-2}}$. The substantially higher gas obscuration seen in the X-rays compared to the optical possibly indicates a warm absorber inside the BLR or merger-driven enhancement of the galactic scale obscuration consistent with optical imaging. This QSO might thus represent an active feeding phase after a recent gas-rich merger.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.25224",
  "author_total": 9,
  "authors": [
    {
      "name": "Xihan Ji"
    },
    {
      "name": "Dominic J. Walton"
    },
    {
      "name": "Francesco D'Eugenio"
    },
    {
      "name": "Ignas Juodžbalis"
    },
    {
      "name": "Vasily Belokurov"
    },
    {
      "name": "Andrew C. Fabian"
    },
    {
      "name": "Roberto Maiolino"
    },
    {
      "name": "Jiamu Huang"
    },
    {
      "name": "Douglas N. C. Lin"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1fqf47eghr00w.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.25224",
  "fulltext_url": null,
  "id": "1fqf47eghr00w",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.25224",
  "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"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.25224",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1fqf47eghr00w.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:39Z",
      "native_id": "2609.25224",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.25224"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Gone with the wind? Potential gas inflow in the broad-line region of a QSO at $z=0.287$ traced by time-varying Balmer absorption",
  "title_text": "Gone with the wind? Potential gas inflow in the broad-line region of a QSO at z=0.287 traced by time-varying Balmer absorption",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:39Z",
  "url": "https://research.draconitic.com/paper/1fqf47eghr00w",
  "venue": "arXiv",
  "versions": []
}