{
  "abstract": "Weak gravitational lensing provides a powerful way to map cosmic structure, but most current measurements rely on galaxy shape distortions from deep imaging surveys and are affected by systematics such as intrinsic alignments, photometric-redshift uncertainties and shape-measurement biases. Here we present a spectroscopic galaxy-galaxy lensing magnification measurement using Fundamental-Plane (FP) size residuals, $δ_r\\equivΔ\\log_{10}R_\\mathrm{e}$, from 3.26 million DESI luminous red galaxy (LRG) sources behind DESI Bright Galaxy Survey lenses. The FP-like relation predicts the intrinsic sizes of LRGs from lensing-invariant quantities, including velocity dispersion $σ_0$ and surface brightness $I_\\mathrm{e}$, with a scatter of about 0.06-0.07 dex. Lensing magnifies LRG sizes, giving the direct convergence response $δ_r(κ)=κ/\\ln 10$, but we show that the full lensing response is modified by magnification bias, because fitting $R_\\mathrm{e}$ with $I_\\mathrm{e}$ inevitably induces a magnitude dependence in $\\barδ_r(m)$. After calibrating this response, we recover surface-density profiles with uncertainties comparable to those from individual Stage-III shear surveys using 5-20 million higher-redshift sources. The corresponding excess surface-density profiles agree with shear-based measurements. We further show that the estimator is robust to size-measurement uncertainties, with a convergence multiplicative bias only $\\simeq -0.2$ times the size bias. FP lensing therefore provides a clean, spectroscopic and complementary probe of cosmic structure.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.09151",
  "author_total": 47,
  "authors": [
    {
      "name": "Kun Xu"
    },
    {
      "name": "Jiaqi Wang"
    },
    {
      "name": "Ravi K Sheth"
    },
    {
      "name": "J Aguilar"
    },
    {
      "name": "S Ahlen"
    },
    {
      "name": "F Beutler"
    },
    {
      "name": "D Bianchi"
    },
    {
      "name": "D Brooks"
    },
    {
      "name": "A Carnero Rosell"
    },
    {
      "name": "T Claybaugh"
    },
    {
      "name": "A de la Macorra"
    },
    {
      "name": "P Doel"
    },
    {
      "name": "J.E Forero-Romero"
    },
    {
      "name": "E Gaztañaga"
    },
    {
      "name": "G Gutierrez"
    },
    {
      "name": "K Honscheid"
    },
    {
      "name": "C Howlett"
    },
    {
      "name": "M Ishak"
    },
    {
      "name": "J Jimenez"
    },
    {
      "name": "S Juneau"
    },
    {
      "name": "R Kehoe"
    },
    {
      "name": "D Kirkby"
    },
    {
      "name": "O Lahav"
    },
    {
      "name": "M Landriau"
    },
    {
      "name": "L Le Guillou"
    },
    {
      "name": "M Manera"
    },
    {
      "name": "A Meisner"
    },
    {
      "name": "R Miquel"
    },
    {
      "name": "J Moustakas"
    },
    {
      "name": "S Nadathur"
    },
    {
      "name": "J.A Newman"
    },
    {
      "name": "W.J Percival"
    },
    {
      "name": "F Prada"
    },
    {
      "name": "I Pérez-Ràfols"
    },
    {
      "name": "C Ravoux"
    },
    {
      "name": "G Rossi"
    },
    {
      "name": "R Ruggeri"
    },
    {
      "name": "E Sanchez"
    },
    {
      "name": "C Saulder"
    },
    {
      "name": "D Schlegel"
    },
    {
      "name": "M Schubnell"
    },
    {
      "name": "H Seo"
    },
    {
      "name": "J Silber"
    },
    {
      "name": "M Siudek"
    },
    {
      "name": "G Tarlé"
    },
    {
      "name": "B.A Weaver"
    },
    {
      "name": "H Zou"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7n91sj94ayh8b.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09151",
  "fulltext_url": null,
  "id": "7n91sj94ayh8b",
  "issns": [],
  "landing_url": "https://hal.science/hal-05758207v1",
  "language": "en",
  "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"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7212086024",
  "pdf_url": "https://arxiv.org/pdf/2609.09151",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7n91sj94ayh8b.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:37Z",
      "native_id": "hal-05758207",
      "source": "hal",
      "url": "https://hal.science/hal-05758207v1"
    },
    {
      "first_seen": "2026-10-30T12:19:53Z",
      "native_id": "2609.09151",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09151"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "Sizing the Universe with DESI Galaxy Sizes: Plain Fundamentals of Fundamental-Plane Lensing",
  "title_text": "Sizing the Universe with DESI Galaxy Sizes: Plain Fundamentals of Fundamental-Plane Lensing",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:53Z",
  "url": "https://research.draconitic.com/paper/7n91sj94ayh8b",
  "venue": "HAL",
  "versions": []
}