{
  "abstract": "Reconstructing the initial conditions of the Universe from late-time tracers would unlock cosmological information buried by non-linear structure formation and astrophysics. We reconstruct the initial density field corresponding to z = 300, with its linear amplitude extrapolated to z = 0, from simulated 21-cm and CO(1–0) line-intensity maps at z = 8 generated with the semi-numerical code, LIMFAST. Using a three-dimensional U-Net, we reconstruct the initial conditions and evaluate their impact on cosmological parameter constraints. The two tracers probe complementary environments: 21-cm emission traces neutral, low-density regions of the intergalactic medium, while CO traces overdense, star-forming regions. We additionally train and evaluate the reconstruction on maps incorporating SKA1-Low– and COMAP-ERA–like instrumental response and thermal noise. In the noiseless case, combining both tracers delivers the most accurate reconstruction across ionisation states, with the cross-correlation coefficient between the reconstructed and true initial density fields, |C(k)| ≳ 0.90 for k ≲ 0.75 Mpc−1. With observational effects, small-scale information is degraded, but the joint reconstruction retains substantial large-scale coherence, with |C(k)| ≳ 0.70 for k ≲ 0.3 Mpc−1. To quantify the cosmological information gain, we perform simulation-based inference using power-spectrum summaries pre- and post-reconstruction. Across an ensemble of realisations, reconstruction yields the largest improvements for σ8 and ns, with a median aggregate marginal compression of 1.17 bits in the noiseless case, corresponding to a 56% reduction in the factorised product of prior-normalised 68% marginal widths. With observational effects, the corresponding median compression is 1.29 bits. These results demonstrate that joint 21-cm–CO reconstruction can recover cosmological information beyond that captured by the pre-reconstruction summaries.",
  "abstract_shown": true,
  "affiliations": [
    "Max-Planck-Insitut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn ,",
    "Van Swinderen Institute, University of Groningen , Nijenborgh 4, 9747 AG Groningen ,",
    "Northwestern University CIERA and Department of Physics and Astronomy, , 1800 Sherman Ave, Evanston, IL 60201 ,",
    "Jet Propulsion Laboratory, California Institute of Technology , 4800 Oak Grove Drive, Pasadena, CA 91109 ,",
    "California Institute of Technology , 1200 E. California Blvd., Pasadena, CA 91125 ,",
    "University of California Department of Astronomy and Astrophysics, , Santa Cruz, 1156 High Stpreet, Santa Cruz, CA 95064 ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Anchal Saxena",
      "orcid": "0000-0002-6631-2256"
    },
    {
      "affs": [
        1
      ],
      "name": "P Daniel Meerburg"
    },
    {
      "affs": [
        2
      ],
      "name": "Guochao Sun"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Tzu-Ching Chang"
    },
    {
      "affs": [
        5
      ],
      "name": "Lluís Mas-Ribas"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7j6p8ma015tvc.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag1972",
  "fulltext_url": null,
  "id": "7j6p8ma015tvc",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag1972/8931748",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7211887494",
  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag1972/72051934/stag1972.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-16",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/7j6p8ma015tvc.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:17Z",
      "native_id": "10.1093/mnras/stag1972",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag1972/8931748"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Cosmology and Gravitation Theories",
      "subfield": "cosmology"
    }
  ],
  "title": "Tracing the Cosmic Origins: Machine Learning Reconstruction of the Primordial Density Field from EoR Observations",
  "title_text": "Tracing the Cosmic Origins: Machine Learning Reconstruction of the Primordial Density Field from EoR Observations",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:17Z",
  "url": "https://research.draconitic.com/paper/7j6p8ma015tvc",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": [
    {
      "doi": "10.48550/arxiv.2609.05412",
      "pid": "ejv6vy5hx5szr",
      "relation": "preprint",
      "title": "Tracing the Cosmic Origins: Machine Learning Reconstruction of the Primordial Density Field from EoR Observations",
      "venue": "arXiv"
    }
  ]
}