{
  "abstract": "Weak gravitational lensing by intervening structure magnifies distant sources and induces scatter in their luminosity distances. We develop an improved stochastic model for the distribution of weak lensing magnifications, $\\textrm{d} P/\\textrm{d}μ$, that resolves individual lenses down to $10^7\\,M_\\odot$ and, besides field halos and filaments, includes subhalos and large-scale clustering of the lens population. Both extensions broaden the distribution, and the resulting scatter in the luminosity distances agrees with the halo-model prediction from the nonlinear matter power spectrum and exceeds that obtained from $N$-body ray tracing, which we attribute to the finite mass resolution and box size of the simulations. Building on this model, we develop \\texttt{FLUMEN}, a conditional normalizing-flow emulator that predicts $\\textrm{d} P/\\textrm{d}μ$ as a function of the source redshift up to $z_s=12$ and six cosmological parameters $\\{h,Ω_M,Ω_B,σ_8,n_s,z_{\\rm eq}\\}$. The emulator enforces the empty-beam cutoff and the fold-caustic power-law tail analytically, and reproduces the Monte Carlo distributions on held-out cosmologies with a median Kullback--Leibler divergence of $0.0048$ at negligible cost. Our results provide a fast and flexible framework for incorporating the full magnification distribution into cosmological analyses of standard sirens, supernovae, and other point sources.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.21806",
  "author_total": 2,
  "authors": [
    {
      "name": "Galymzhan Baltabay"
    },
    {
      "name": "Ville Vaskonen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4bfj6rtnfmaq0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.21806",
  "fulltext_url": null,
  "id": "4bfj6rtnfmaq0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.21806",
  "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": null,
  "pdf_url": "https://arxiv.org/pdf/2609.21806",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4bfj6rtnfmaq0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:03Z",
      "native_id": "2609.21806",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.21806"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    }
  ],
  "title": "FLUMEN: Neural Emulator of an Advanced Stochastic Weak Lensing Model",
  "title_text": "FLUMEN: Neural Emulator of an Advanced Stochastic Weak Lensing Model",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:03Z",
  "url": "https://research.draconitic.com/paper/4bfj6rtnfmaq0",
  "venue": "arXiv",
  "versions": []
}