{
  "abstract": "Deeply bound stellar substructures of about 1 kpc at the center of bulges are found in a subset of galaxies from the cosmological chemo-hydrodynamical zoom-in CIELO simulation suite. They were identified as stellar overdensities at the lowest binding energies in each galaxy's circularity-energy $(ε, E)$ plane. We refer to these overdensities as stellar knots. We aim to characterize their properties in the context of bulge assembly using CIELO simulated galaxies spanning a wide range of stellar masses ($10^{8.0}$-$10^{10.7}\\,\\mathrm{M}_{\\odot}$), with diverse formation histories. We inspect 54 galactic bulges. Within them, we isolate stellar knot candidates in $(ε, E)$ space, and identify 28 robust knots satisfying successive selection criteria: kinematic, concentration, and morphology. We characterize their chemical enrichment, formation timescales, formation sites, progenitor gas origin, and spatial distributions. Across all galaxy masses, knots are systematically alpha-element enhanced, having assembled the bulk of their stellar mass at earlier epochs and on shorter timescales than other bulge populations, with a median of $\\sim$2$\\,$Gyr versus $\\sim$5$\\,$Gyr. Regarding their origin, knots are predominantly in-situ ($5\\%$ accreted mass fraction, roughly half that of the rest of the bulge), with negligible disk-born stars contribution and the largest gas fractions originating from a primordial central spheroid ($21\\%$ versus 16--17$\\%$ for the surrounding populations), consistent with being the primary gas fuel for the alpha-element enhancement. In terms of structure, knots exhibit a variety of morphologies, with spheroidal shapes predominating. Dynamical selection in $(ε, E)$ space of CIELO galaxies demonstrates its effectiveness in recovering coeval stellar populations, pointing to stellar knots as plausible fossil signatures of early in-situ bulge assembly.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.11465",
  "author_total": 10,
  "authors": [
    {
      "name": "Belén Acosta-Tripailao"
    },
    {
      "name": "Patricia B. Tissera"
    },
    {
      "name": "Manuela Zoccali"
    },
    {
      "name": "Jenny Gonzalez-Jara"
    },
    {
      "name": "Brian Tapia-Contreras"
    },
    {
      "name": "Ignacio Muñoz-Escobar"
    },
    {
      "name": "Susana Pedrosa"
    },
    {
      "name": "Nelson D. Padilla"
    },
    {
      "name": "Lucas Bignone"
    },
    {
      "name": "Rosa Dominguez-Tenreiro"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5ad49vpwbjs17.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.11465",
  "fulltext_url": null,
  "id": "5ad49vpwbjs17",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.11465",
  "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": null,
  "pdf_url": "https://arxiv.org/pdf/2609.11465",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-10",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5ad49vpwbjs17.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:26Z",
      "native_id": "2609.11465",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.11465"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "The properties of central stellar knots embedded in galactic bulges of CIELO simulations",
  "title_text": "The properties of central stellar knots embedded in galactic bulges of CIELO simulations",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:26Z",
  "url": "https://research.draconitic.com/paper/5ad49vpwbjs17",
  "venue": "arXiv",
  "versions": []
}