{
  "abstract": "Intracluster light (ICL) offers a luminous route for measuring the shapes and orientations of cluster haloes. We used Euclid Quick Data Release (Q1) images to quantify ICL shapes for 205 clusters at $0.1 \\leq z \\leq 0.8$ selected from the eROSITA All-Sky Survey and the Dark Energy Survey. We measured the ICL properties across five bands ($I_\\mathrm{E}$, $Y_\\mathrm{E}$, $J_\\mathrm{E}$, $H_\\mathrm{E}$ and the coadded $YJH_\\mathrm{E}$), and find that the shape parameters are consistent across the filters, with the $H_\\mathrm{E}$ band probing the profiles to the largest cluster-centric distances ($0.1R_{200\\mathrm{c}}\\sim100$ kpc). The ICL ellipticity ($e=1-b/a$) distribution peaks at 0.5, consistent with halo ellipticities inferred from strong and weak lensing studies, suggesting that the ICL traces the large-scale structure of the clusters. Cluster cores, dominated by brightest cluster galaxy (BCG) light, are round ($e\\sim0.2$), while the ICL becomes progressively more elongated at large radii, reaching an ellipticity of $\\sim0.5$ by $0.1R_{200\\mathrm{c}}$. We find that the ICL is closely aligned with the BCG (87% lie within 30$^\\circ$), but shows a weaker alignment with the satellite galaxy distribution (61% within 30$^\\circ$). Robust position angles could be measured using the ICL for 63% of the sample, whereas position angles could be measured for only 30% of the sample using the satellite galaxies. Stacking clusters in redshift bins allows measurements of the ICL surface brightness to $0.6$-$0.8R_{200\\mathrm{c}}$ and ellipticity beyond $0.3$-$0.4R_{200\\mathrm{c}}$ (300-400 kpc), but we observed a plateau in the ICL ellipticity beyond $0.1R_{200\\mathrm{c}}$. These results demonstrate the capability of Euclid to characterise the ICL morphology with high statistical precision, allowing new constraints on cluster halo structure and its evolution with redshift.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.29683",
  "author_total": 330,
  "authors": [
    {
      "name": "Euclid Collaboration"
    },
    {
      "name": "T. Kolcu"
    },
    {
      "name": "N. A. Hatch"
    },
    {
      "name": "A. Fernandez"
    },
    {
      "name": "S. P. Bamford"
    },
    {
      "name": "H. Gao"
    },
    {
      "name": "J. B. Golden-Marx"
    },
    {
      "name": "G. Martin"
    },
    {
      "name": "Y. M. Bahé"
    },
    {
      "name": "S. L. Ahad"
    },
    {
      "name": "C. Bellhouse"
    },
    {
      "name": "J. Butler"
    },
    {
      "name": "S. de Nicola"
    },
    {
      "name": "F. Durret"
    },
    {
      "name": "A. Ellien"
    },
    {
      "name": "A. H. Gonzalez"
    },
    {
      "name": "H. Gully"
    },
    {
      "name": "M. Kluge"
    },
    {
      "name": "M. Maturi"
    },
    {
      "name": "M. Montes"
    },
    {
      "name": "L. Moscardini"
    },
    {
      "name": "R. Ragusa"
    },
    {
      "name": "A. Saro"
    },
    {
      "name": "M. Urbano"
    },
    {
      "name": "N. Aghanim"
    },
    {
      "name": "B. Altieri"
    },
    {
      "name": "S. Andreon"
    },
    {
      "name": "N. Auricchio"
    },
    {
      "name": "C. Baccigalupi"
    },
    {
      "name": "M. Baldi"
    },
    {
      "name": "S. Bardelli"
    },
    {
      "name": "P. Battaglia"
    },
    {
      "name": "R. Bender"
    },
    {
      "name": "A. Biviano"
    },
    {
      "name": "M. Bolzonella"
    },
    {
      "name": "E. Branchini"
    },
    {
      "name": "M. Brescia"
    },
    {
      "name": "S. Camera"
    },
    {
      "name": "G. Cañas-Herrera"
    },
    {
      "name": "V. Capobianco"
    },
    {
      "name": "C. Carbone"
    },
    {
      "name": "J. Carretero"
    },
    {
      "name": "S. Casas"
    },
    {
      "name": "M. Castellano"
    },
    {
      "name": "G. Castignani"
    },
    {
      "name": "S. Cavuoti"
    },
    {
      "name": "K. C. Chambers"
    },
    {
      "name": "A. Cimatti"
    },
    {
      "name": "C. Colodro-Conde"
    },
    {
      "name": "G. Congedo"
    },
    {
      "name": "C. J. Conselice"
    },
    {
      "name": "L. Conversi"
    },
    {
      "name": "Y. Copin"
    },
    {
      "name": "F. Courbin"
    },
    {
      "name": "H. M. Courtois"
    },
    {
      "name": "M. Cropper"
    },
    {
      "name": "J. -C. Cuillandre"
    },
    {
      "name": "A. Da Silva"
    },
    {
      "name": "H. Degaudenzi"
    },
    {
      "name": "G. De Lucia"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/a557g6f6zc4fp.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.29683",
  "fulltext_url": null,
  "id": "a557g6f6zc4fp",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.29683",
  "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": "W7223204038",
  "pdf_url": "https://arxiv.org/pdf/2610.29683",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/a557g6f6zc4fp.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:19Z",
      "native_id": "2610.29683",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.29683"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Euclid Quick Data Release (Q1). The shape of cluster haloes revealed by intracluster light",
  "title_text": "Euclid Quick Data Release (Q1). The shape of cluster haloes revealed by intracluster light",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:19Z",
  "url": "https://research.draconitic.com/paper/a557g6f6zc4fp",
  "venue": "arXiv",
  "versions": []
}