{
  "abstract": "We update the X-ray information given in Maselli et al. (2024) for five bright radio sources in the SMS4 catalog, thanks to additional observations with the X-Ray Telescope (XRT) on board the Neil Gehrels Swift Observatory (hereafter Swift) carried out through February 2026. X-ray emission from MRC B1754-597, previously based only on data from the eROSITA-DE DR1 catalogs, is now detected also by Swift, which yields a more precise positional uncertainty. Thanks to ~7 ks of additional exposure with Swift we are now able to detect MRC B1817-391, a source for which no X-ray counterpart is found in eROSITA-DE DR1. Another source that is not detected in the eROSITA-DE DR1 catalogs, and that was not observed by Swift earlier than 2025, is MRC B1827-360: with a ~6 ks X-ray observation, the source is detected. Finally, based on ~8 ks of additional exposure, we detect X-ray emission for MRC B2032-350, a source that lies out of the DR1 footprint. In contrast, additional exposure (~2 ks) just gives an upper limit on the X-ray emission of MRC B1814-519. The analysis of the extent and the hardness ratio of the four detected X-ray sources suggests the presence of soft, diffuse X-ray emission as expected from galaxy group cores or hot galaxy coronae. Using the positional uncertainty of the X-ray detections to constrain the search for counterparts at lower energies, we provide a new infrared/optical counterpart for MRC B1817-391 and confirm the counterparts previously reported in the literature for the three remaining sources.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.04310",
  "author_total": 5,
  "authors": [
    {
      "name": "Alessandro Maselli"
    },
    {
      "name": "William R. Forman"
    },
    {
      "name": "Christine Jones"
    },
    {
      "name": "Ralph P. Kraft"
    },
    {
      "name": "Matteo Perri"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6tdzjebpz9f74.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.04310",
  "fulltext_url": null,
  "id": "6tdzjebpz9f74",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.04310",
  "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.HE"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.04310",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6tdzjebpz9f74.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:14Z",
      "native_id": "2609.04310",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.04310"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "A Swift X-ray view of the SMS4 sample - III: Deeper insight into previously undetected sources",
  "title_text": "A Swift X-ray view of the SMS4 sample - III: Deeper insight into previously undetected sources",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:14Z",
  "url": "https://research.draconitic.com/paper/6tdzjebpz9f74",
  "venue": "arXiv",
  "versions": []
}