{
  "abstract": "Extragalactic foregrounds contaminate cosmic microwave background (CMB) temperature maps at small angular scales and limit their utility for precision cosmology. The internal linear combination (ILC) is a well-known technique for suppressing these contaminants, but residual foreground power remains a limiting factor. Kusiak et al. (2023) proposed adding galaxy number-density maps as additional ILC channels, exploiting their correlation with the large-scale structure sourcing these foregrounds to suppress contamination. Here we apply this framework to forecast the gains in CMB-based cosmological parameter constraints from near- and next-generation experiments. Using a halo-model foreground pipeline and a Fisher forecast from joint TT+TE+EE power spectra, we quantify the improvement from galaxy-tracer-assisted ILC cleaning across three configurations: enhanced Simons Observatory (SO) with unWISE or Rubin-like galaxy catalogs, and a futuristic CMB-HD configuration with a hypothetical deep galaxy survey. We find that adding galaxy tracers reduces the residual foreground power in the cleaned temperature map by $\\sim4\\%$, $\\sim22\\%$, and $\\sim32\\%$ at $\\ell\\sim10,000$ for the unWISE, Rubin-like, and futuristic samples, respectively. For the overall variance of the cleaned map at $\\ell\\sim10,000$, it provides $8\\%$, $24\\%$, and $17\\%$ improvements for each combination. The resulting reduction in marginalized parameter error bars is modest for the base six-parameter $Λ$CDM model: sub-percent for SO+unWISE, rising to $\\sim2\\%$ for SO+Rubin-like tracer. Including the effective number of relativistic species $N_{\\rm eff}$, we find at most $2.2\\%$ improvements for both SO+Rubin-like and CMB-HD+Futuristic tracer. These results establish the expected gains from combining near-term CMB experiments with current and forthcoming large-scale-structure surveys.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.28487",
  "author_total": 2,
  "authors": [
    {
      "name": "Shu-Fan Chen"
    },
    {
      "name": "J. Colin Hill"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/efpxqm2j78f7w.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.28487",
  "fulltext_url": null,
  "id": "efpxqm2j78f7w",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.28487",
  "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.CO"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7204833655",
  "pdf_url": "https://arxiv.org/pdf/2608.28487",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/efpxqm2j78f7w.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "2608.28487",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.28487"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    }
  ],
  "title": "Enhancing Cosmological Constraints from Foreground-Cleaned CMB Maps Using Large-Scale Structure Surveys",
  "title_text": "Enhancing Cosmological Constraints from Foreground-Cleaned CMB Maps Using Large-Scale Structure Surveys",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/efpxqm2j78f7w",
  "venue": "arXiv",
  "versions": []
}