{
  "abstract": "Action-based distribution functions $f(\\mathbf{J})$ provide a powerful description of stellar systems. Consequently, the construction of physically accurate and dynamically stable $f(\\mathbf{J})$ for galactic components has emerged as a key challenge in the field. In this study, we present GroArnold, a computational framework designed to construct analytical $f(\\mathbf{J})$ expressions for axisymmetric and triaxial galaxies and dark matter halos. The framework integrates modules for $N$-body initial condition generation, $N$-body simulation, angle--action variable estimation, and distribution-function fitting into a unified workflow. It supports a wide range of density profiles and kinematic properties, and is uniquely designed to generate stable $N$-body models for user-specified galactic systems, with the aim of obtaining an $f(\\mathbf{J})$ that approximates a dynamically stable and physically consistent state. To this end, we extend the triaxial Stäckel Fudge method of the TACT code, implemented in our Nbody-TACT module, to enable action estimation directly from $N$-body gravitational potentials. GroArnold provides a robust and flexible tool for deriving numerically empirical, explicitly analytical distribution functions for user-specified galaxies or halos, thereby facilitating a wide range of practical $f(\\mathbf{J})$-based modeling applications. In addition, it serves as a powerful tool for investigating the dynamics of realistic triaxial galaxies and halos beyond the scope of traditional spherical or axisymmetric models. We assessed the accuracy of the output $f(\\mathbf{J})$ by comparing its predicted spatial and velocity distributions with those of the input $N$-body snapshot, and confirmed that it provides a reasonably accurate representation of the input. The code is modular, publicly available, and designed to support future extensions and adaptations.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18978",
  "author_total": 4,
  "authors": [
    {
      "name": "Jian-Yu Gu"
    },
    {
      "name": "Xiao-Bo Dong"
    },
    {
      "name": "Shi-Yan Zhong"
    },
    {
      "name": "Run-Yu Meng"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4jj4d1p23r2jt.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18978",
  "fulltext_url": null,
  "id": "4jj4d1p23r2jt",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.18978",
  "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.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7222282171",
  "pdf_url": "https://arxiv.org/pdf/2610.18978",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4jj4d1p23r2jt.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:28Z",
      "native_id": "2610.18978",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18978"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "GroArnold: A Framework for Constructing Action-based Models for Triaxial Galaxies and Dark Matter Halos",
  "title_text": "GroArnold: A Framework for Constructing Action-based Models for Triaxial Galaxies and Dark Matter Halos",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:47Z",
  "url": "https://research.draconitic.com/paper/4jj4d1p23r2jt",
  "venue": "arXiv",
  "versions": []
}