{
  "abstract": "The stellar halo of the Milky Way (MW) exhibits a weak net prograde rotational signal ($v_ϕ \\lesssim 25$ km~s$^{-1}$), yet its origin remains unexplained. To investigate this, we use the Auriga cosmological simulation suite of MW-mass haloes to probe the rotation of stellar haloes over the redshift range $z_{\\mathrm{red}}=0-2.5$. The rotational signal is found to persist over this redshift range. We show that satellite progenitors of the stellar halo exhibit a non-uniform distribution of infall directions, with a tendency to align with the host disc, albeit with significant scatter. Thus, we attribute the net rotation to the anisotropic accretion of satellites. Haloes that host \\textit{Gaia}-Enceladus-Sausage (GES)-like substructures exhibit consistently slower rotational velocity, likely due to the head-on, more radial trajectory of the dominant progenitor in such systems. Haloes whose stellar discs have reorientated by $\\geq 90^{\\circ}$ also exhibit slower rotation, likely because the longer dynamical timescales of haloes prevent them from quickly adjusting to disc reorientations. We also report a correlation between the rotation of stellar and dark matter haloes, suggesting a possible common origin driven by anisotropic accretion. We therefore suggest that the MW experienced a disc flip and has a slowly rotating dark matter halo.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.01208",
  "author_total": 6,
  "authors": [
    {
      "name": "Kirill Batrakov"
    },
    {
      "name": "Alis J. Deason"
    },
    {
      "name": "Francesca Fragkoudi"
    },
    {
      "name": "Thomas Tomlinson"
    },
    {
      "name": "Azadeh Fattahi"
    },
    {
      "name": "Vasily Belokurov"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/44a60p2ghrc23.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.01208",
  "fulltext_url": null,
  "id": "44a60p2ghrc23",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.01208",
  "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/2609.01208",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/44a60p2ghrc23.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.01208",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.01208"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Slow stellar halo rotation as a signature of disc flips and GES-like mergers",
  "title_text": "Slow stellar halo rotation as a signature of disc flips and GES-like mergers",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/44a60p2ghrc23",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1093/mnras/stag1668",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}