{
  "abstract": "We develop an effective field theory (EFT) of intrinsic alignments at the level of spin-2 field fluctuations of large-scale structure tracers, such as the shapes of galaxies and dark matter halos. Our perturbative model includes the non-linear treatment of the Zel'dovich displacement, and contains all necessary shape operators through the third order. We apply our field-level model to the full 3D distribution of galaxy shapes, whose sky projections are a known contaminant of cosmic shear measurements. Our field-level EFT model achieves a better description of the helicity fields of dark matter halo shapes than the standard non-linear alignment (NLA) and tidal torquing + tidal alignment (TATT) models in the literature, as evidenced by improved correlations with the simulations' initial conditions. We perform precision measurements of field-level bias parameters by means of a generalized least-squares problem, for which we derive an optimal estimator and analytic covariance matrices. We measure the full set of linear, quadratic, and cubic shape bias coefficients as a function of halo mass in the $\\texttt{Quijote}$ N-body simulations. We then study the intrinsic alignments of galaxies in the $\\texttt{FLAMINGO}$ hydrodynamical simulation, focusing on observationally relevant samples: spirals, ellipticals, luminous red galaxies (LRG) and emission-line galaxies (ELG). We detect linear and nonlinear alignment coefficients at high significance for LRG, spiral and elliptical galaxies. We also find evidence for non-zero density-weighted tidal bias coefficient of the simulated ELG. This work supports the notion that EFT-based models of alignments will be paramount in optimally extracting constraints from future shape correlations, and lays the foundation for the development of simulation-based priors for future galaxy shape samples.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.36027",
  "author_total": 3,
  "authors": [
    {
      "name": "Nickolas Kokron"
    },
    {
      "name": "Mikhail M. Ivanov"
    },
    {
      "name": "James M. Sullivan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ajbanmctdb0a8.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.36027",
  "fulltext_url": null,
  "id": "ajbanmctdb0a8",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.36027",
  "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"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.36027",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-26",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ajbanmctdb0a8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:50Z",
      "native_id": "2610.36027",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.36027"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Field-level modeling of halo and galaxy alignments",
  "title_text": "Field-level modeling of halo and galaxy alignments",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:50Z",
  "url": "https://research.draconitic.com/paper/ajbanmctdb0a8",
  "venue": "arXiv",
  "versions": []
}