{
  "abstract": "The Dark Energy Spectroscopic Instrument (DESI) measures baryon acoustic oscillations (BAO) in the Lyman-$α$ (Lyman-alpha) forest and provides a robust probe of the expansion history in the matter-dominated era. Yet, non-linear structure formation broadens and shifts the BAO peak. To undo these effects, we extend standard Zel'dovich reconstruction, routinely applied to galaxy surveys, to the Lyman-alpha forest. We validate our methodology on large-volume idealized Lyman-alpha forest mocks painted on top of the \\textsc{AbacusSummit} $N$-body simulations, using linear control variates to suppress sample variance and thereby reduce the error bars by a factor of up to $\\approx \\sqrt{50}$. In fully sampled periodic boxes, reconstruction halves the radial BAO damping scale and reduces the uncertainties on the radial ($\\apar$) and transverse ($\\aperp$) scaling parameters by $\\approx25\\%$ and $\\approx15\\%$, respectively. It also reduces the non-linear shift from $Δ\\apar=+0.3\\%$ to $+0.10\\pm0.07\\%$, while $\\aperp$ remains unbiased. To make this approach readily applicable to observational data, we demonstrate the impact of a survey mask with a DESI-like density of $50\\,\\mathrm{deg}^{-2}$. For this mask, we compare two approaches to estimate the displacement field: either directly from the Lyman-alpha forest or using an external tracer with a number density of $\\bar n \\simeq 10^{-3}\\,h^3\\mathrm{Mpc}^{-3}$, such as Lyman-break galaxies and Lyman-$α$ emitters---both key targets for DESI-II. Both approaches give comparable gains and reduce the uncertainties on $\\apar$ and $\\aperp$ by $\\approx 27\\%$ and $\\approx 10\\%$, respectively, with mild improvements for futuristic high-density surveys with $160\\,\\mathrm{deg}^{-2}$. Correspondingly, the figure of merit improves by factors of $1.66$ for fully sampled boxes, $1.65$ for a DESI-like, and $1.76$ for a high-density survey.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.37664",
  "author_total": 2,
  "authors": [
    {
      "name": "Boryana Hadzhiyska"
    },
    {
      "name": "Roger de Belsunce"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ajxvqpf978ts4.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.37664",
  "fulltext_url": null,
  "id": "ajxvqpf978ts4",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.37664",
  "language": null,
  "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"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7224108714",
  "pdf_url": "https://arxiv.org/pdf/2610.37664",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ajxvqpf978ts4.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:50Z",
      "native_id": "2610.37664",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.37664"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    }
  ],
  "title": "Improving cosmological distance measurements at high redshift using Lyman-Alpha forest BAO reconstruction",
  "title_text": "Improving cosmological distance measurements at high redshift using Lyman-Alpha forest BAO reconstruction",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:50Z",
  "url": "https://research.draconitic.com/paper/ajxvqpf978ts4",
  "venue": "arXiv",
  "versions": []
}