{
  "abstract": "We report the discovery and early outburst evolution of the new Galactic magnetar EP J223759.5+531421, detected by the Einstein Probe Wide-field X-ray Telescope on 2026 June 28. Follow-up observations with Einstein Probe, XMM--Newton, NuSTAR, SVOM, and IXPE revealed coherent X-ray pulsations at P ~ 6s and an average period derivative of Pdot ~ 2.8x10^{-12} s/s. These values imply a nominal polar dipolar magnetic field of B_dip ~ 2.6x10^{14} Gauss and a characteristic age of tau_c ~ 34 kyr, although the structured timing residuals suggest possible torque variability. The rms pulsed fraction is approximately 20-25% below ~7 keV and decreases at higher energies. The broadband spectra require multiple thermal components and a hard power-law tail. Adopting a distance of 3.3 kpc, the 0.5-30 keV luminosity declined from 1.2x10^{35} to 5.7x10^{34} erg/s during the first month, accompanied by a decrease in the inferred thermal-emitting areas. At this distance, the Galactic latitude b=-4.56 deg corresponds to a height of approximately 0.26 kpc below the Galactic plane, which is difficult to reconcile with the nominal characteristic age under a simple midplane-birth scenario even for an extreme proper motion velocity. Short X-ray bursts independently confirm the magnetar nature of the source. No near-infrared or radio counterpart were detected by GTC, Medicina or FAST, respectively, down to K_s>21 mag and S_{1.25 GHz} <2.3 microJy. These observations demonstrate the potential of the Einstein Probe WXT monitoring to uncover previously quiescent Galactic magnetars and follow their outbursts from their earliest observed stages.",
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  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.25990",
  "author_total": 47,
  "authors": [
    {
      "name": "N Rea"
    },
    {
      "name": "F Coti Zelati"
    },
    {
      "name": "A Borghese"
    },
    {
      "name": "Y.L Wang"
    },
    {
      "name": "H Yang"
    },
    {
      "name": "X Mao"
    },
    {
      "name": "C.-Y Dai"
    },
    {
      "name": "E Arrigoni"
    },
    {
      "name": "J Bai"
    },
    {
      "name": "G Bernardi"
    },
    {
      "name": "M Burgay"
    },
    {
      "name": "S Cao"
    },
    {
      "name": "A Coleiro"
    },
    {
      "name": "D de Grandis"
    },
    {
      "name": "P Esposito"
    },
    {
      "name": "H Feng"
    },
    {
      "name": "Y.-C Fu"
    },
    {
      "name": "A Geminardi"
    },
    {
      "name": "D Götz"
    },
    {
      "name": "S Guillot"
    },
    {
      "name": "Y Huang"
    },
    {
      "name": "M Imbrogno"
    },
    {
      "name": "G.L Israel"
    },
    {
      "name": "C Jin"
    },
    {
      "name": "A Kong"
    },
    {
      "name": "Y Li"
    },
    {
      "name": "L Lin"
    },
    {
      "name": "C.-S Liu"
    },
    {
      "name": "C Maitra"
    },
    {
      "name": "A Marino"
    },
    {
      "name": "S Mereghetti"
    },
    {
      "name": "J.-U Ness"
    },
    {
      "name": "S Ng"
    },
    {
      "name": "M Pilia"
    },
    {
      "name": "A Possenti"
    },
    {
      "name": "H Sun"
    },
    {
      "name": "L Tao"
    },
    {
      "name": "R Taverna"
    },
    {
      "name": "A Tiengo"
    },
    {
      "name": "R Turolla"
    },
    {
      "name": "W Yuan"
    },
    {
      "name": "S Zane"
    },
    {
      "name": "B Zhang"
    },
    {
      "name": "L.-X Zhang"
    },
    {
      "name": "Z Zhang"
    },
    {
      "name": "W.-W Zhu"
    },
    {
      "name": "Y.-C Zou"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f2fevqaxtscxe.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.25990",
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  "id": "f2fevqaxtscxe",
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  "landing_url": "https://hal.science/hal-05785797v1",
  "language": "en",
  "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",
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    [
      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
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  "openalex": "W7214074398",
  "pdf_url": "https://arxiv.org/pdf/2609.25990",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f2fevqaxtscxe.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:50Z",
      "native_id": "hal-05785797",
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    {
      "first_seen": "2026-10-30T12:23:39Z",
      "native_id": "2609.25990",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.25990"
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  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
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    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
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  ],
  "title": "Einstein Probe discovery of the magnetar EP J223759.5+531421",
  "title_text": "Einstein Probe discovery of the magnetar EP J223759.5+531421",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:39Z",
  "url": "https://research.draconitic.com/paper/f2fevqaxtscxe",
  "venue": "HAL",
  "versions": []
}