{
  "id": "2412.03707",
  "version": "v1",
  "published": "2024-12-04T20:44:20.000Z",
  "updated": "2024-12-04T20:44:20.000Z",
  "title": "Stellar-gas kinematic misalignments in EAGLE: lifetimes and longevity of misaligned galaxies",
  "authors": [
    "Maximilian K. Baker",
    "Timothy A. Davis",
    "Freeke van de Voort",
    "Ilaria Ruffa"
  ],
  "comment": "20 pages, 14 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The dominant processes by which galaxies replenish their cold gas reservoirs remain disputed, especially in massive galaxies. Stellar-gas kinematic misalignments offer an opportunity to study these replenishment processes. However, observed distributions of these misalignments conflict with current models of gas replenishment in early-type galaxies (ETGs), with longer relaxation timescales suggested as a possible solution. We use the EAGLE simulation to explore the relaxation of unstable misaligned gas in galaxies with masses of $M_{*}\\geqslant \\mathrm{10^{9.5}}$ M$_\\odot$ between $0<z<1$. We extract misalignments from formation to relaxation providing a sample of $\\sim3200$ relaxations. We find relaxation timescales tend to be short-duration, with median lifetimes of $\\sim0.5$ Gyr, though with a notable population of unstable misalignments lasting $\\gtrsim1$ Gyr. Relaxation time distributions show a log-linear relationship, with $\\approx20\\%$ of unstable misalignments persisting for $\\gtrsim3$ torquing times. Long-lived unstable misalignments are predominantly found in galaxies with higher stellar masses, lower star-forming gas fractions, higher ongoing gas inflow, and which reside in the centres of dense environments. Mergers only cause $\\sim17\\%$ of unstable misalignments in EAGLE. We conclude that, at least in EAGLE, unstable kinematic misalignments are not predominantly driven by gas-rich minor mergers. Additionally, processes that significantly extend relaxation times are not dominant in the galaxy population. Instead, we see a diverse formation pathway for misalignments such as through hot halo cooling.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-12-04T20:44:20.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "misaligned galaxies",
      "unstable misalignments",
      "stellar-gas kinematic misalignments offer",
      "cold gas reservoirs remain",
      "longer relaxation timescales"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 20,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}