{
  "abstract": "EP J062132.0+623837 is a new X-ray source identified in 14-day binned survey data from the Wide-field X-ray Telescope aboard the Einstein Probe (EP). Subsequent X-ray observations with the Follow-up X-ray Telescope (FXT) on board EP localized the source to the central region of the galaxy 2MASX J06213207+6238390 at $z=0.084$. Here, we present a comprehensive analysis of the multi-wavelength data for this object. During the FXT and Swift/XRT follow-up, the source remained X-ray active, with observed luminosities of $(3-9)\\times10^{43}$ erg s$^{-1}$, and its X-ray spectra were well described by power-law models with photon indices of $Γ\\sim1.5$. The optical spectrum of the host galaxy clearly reveals a broad-line active galactic nucleus (AGN) exhibiting significantly enhanced broad Balmer emission lines compared to an archival spectrum obtained four years earlier, thereby marking a changing-look transition from Type 1.8 to Type 1.5. Furthermore, long-term optical and mid-infrared light curves indicate that the nucleus underwent dramatic brightening around 2010 and has since shown substantial variability. Given the spatial coincidence and multi-wavelength behavior, we identify EP J062132.0+623837 as a changing-look AGN, initially detected by EP and subsequently confirmed to exhibit large-amplitude variability across multiple bands. This case study demonstrates the great potential of wide-field time-domain X-ray surveys for discovering changing-look AGNs, paving a new avenue for their systematic identification as a powerful complement to ongoing optical surveys.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.30959",
  "author_total": 18,
  "authors": [
    {
      "name": "Lin-Na Xu"
    },
    {
      "name": "Ning Jiang"
    },
    {
      "name": "Tinggui Wang"
    },
    {
      "name": "Shifeng Huang"
    },
    {
      "name": "Yibo Wang"
    },
    {
      "name": "Zhenfeng Sheng"
    },
    {
      "name": "Mingxin Wu"
    },
    {
      "name": "Jiazheng Zhu"
    },
    {
      "name": "Huaqing Cheng"
    },
    {
      "name": "Chichuan Jin"
    },
    {
      "name": "Jun-Jie Jin"
    },
    {
      "name": "Dongyue Li"
    },
    {
      "name": "Yuan Liu"
    },
    {
      "name": "Jianwei Lyu"
    },
    {
      "name": "Jian-Guo Wang"
    },
    {
      "name": "Yun-Fei Xu"
    },
    {
      "name": "Yongquan Xue"
    },
    {
      "name": "Zhen Zhang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dsgzfhyr6rv2x.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.30959",
  "fulltext_url": null,
  "id": "dsgzfhyr6rv2x",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.30959",
  "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"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7223270905",
  "pdf_url": "https://arxiv.org/pdf/2610.30959",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dsgzfhyr6rv2x.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.30959",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.30959"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "EP J062132.0+623837: A Multi-wavelength Study of a Changing-look Active Galactic Nucleus Discovered by Einstein Probe",
  "title_text": "EP J062132.0+623837: A Multi-wavelength Study of a Changing-look Active Galactic Nucleus Discovered by Einstein Probe",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/dsgzfhyr6rv2x",
  "venue": "arXiv",
  "versions": []
}