{
  "abstract": "We report a direct measurement of the 21-cm signal from neutral hydrogen (HI) via the intensity mapping technique at redshift $z = 0.42$ through its power spectrum at cosmological scales $0.095\\,h\\,{\\rm Mpc}^{-1}<k<0.245\\,h\\,{\\rm Mpc}^{-1}$. We analyse intensity maps observed in the frequency range $971.2\\,{\\rm MHz}<ν<1023.6\\,{\\rm MHz}$ during the 2021 observational campaign of the MeerKAT Large Area Synoptic Survey (MeerKLASS) spanning an area of approximately $236\\,{\\rm deg}^2$. Capitalising on the depth of this survey, we divide the data set into multiple observationally independent subsets. After performing blind contaminant separation independently on each subset, we exploit internal cross-correlations to suppress the instrumental noise plateau and isolate the cosmological signal from residual systematics. Although the subsets' auto-spectra show the presence of excess power that we deem linked to still unresolved systematics, the cross-spectra measurements satisfactorily pass a battery of null and robustness tests. We introduce a multi-subset formalism to infer the amplitude of the HI auto-spectrum from our internal cross-spectra measurements while marginalising the potential signal loss that occurs during data processing, reaching a detection with signal-to-noise ratio of 6.2. We constrain the clustering amplitude of the signal in terms of the HI cosmic abundance and its linear bias, measuring $10^3\\,Ω_{\\rm HI} b_{\\rm HI}=1.271^{+1.080}_{-0.598}$. This direct measurement marks a milestone in demonstrating the effectiveness of the HI intensity mapping technique for future surveys with the SKA Observatory, of which MeerKAT is a precursor.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.12158",
  "author_total": 18,
  "authors": [
    {
      "name": "Matilde Barberi-Squarotti"
    },
    {
      "name": "José L Bernal"
    },
    {
      "name": "Philip Bull"
    },
    {
      "name": "Stefano Camera"
    },
    {
      "name": "Isabella P Carucci"
    },
    {
      "name": "Zhaoting Chen"
    },
    {
      "name": "Steven Cunnington"
    },
    {
      "name": "Brandon N Engelbrecht"
    },
    {
      "name": "José Fonseca"
    },
    {
      "name": "Keith Grainge"
    },
    {
      "name": "Wenkai Hu"
    },
    {
      "name": "Melis O Irfan"
    },
    {
      "name": "Yichao Li"
    },
    {
      "name": "Mário G Santos"
    },
    {
      "name": "Marta Spinelli"
    },
    {
      "name": "Jingying Wang"
    },
    {
      "name": "Amadeus Witzemann"
    },
    {
      "name": "Laura Wolz"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/38mfnh4q8a0p9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.12158",
  "fulltext_url": null,
  "id": "38mfnh4q8a0p9",
  "issns": [],
  "landing_url": "https://hal.science/hal-05842227v1",
  "language": "en",
  "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.CO"
    ],
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ],
    [
      "openalex",
      "3103|Radio Astronomy Observations and Technology"
    ]
  ],
  "openalex": "W7221118894",
  "pdf_url": "https://arxiv.org/pdf/2610.12158",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/38mfnh4q8a0p9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:02Z",
      "native_id": "hal-05842227",
      "source": "hal",
      "url": "https://hal.science/hal-05842227v1"
    },
    {
      "first_seen": "2026-10-30T12:27:54Z",
      "native_id": "2610.12158",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.12158"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "HI intensity mapping with MeerKAT: A measurement of the 21-cm auto-spectrum on cosmological scales",
  "title_text": "HI intensity mapping with MeerKAT: A measurement of the 21-cm auto-spectrum on cosmological scales",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:54Z",
  "url": "https://research.draconitic.com/paper/38mfnh4q8a0p9",
  "venue": "HAL",
  "versions": []
}