{
  "id": "2407.07971",
  "version": "v1",
  "published": "2024-07-10T18:10:28.000Z",
  "updated": "2024-07-10T18:10:28.000Z",
  "title": "Modeling the Ages and Chemical Abundances of Elliptical Galaxies",
  "authors": [
    "Nicole Marcelina Gountanis",
    "David H. Weinberg",
    "Aliza G. Beverage",
    "Nathan R. Sandford",
    "Charlie Conroy",
    "Mariska Kriek"
  ],
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Spectroscopic studies of elliptical galaxies show that their stellar population ages, mean metallicity, and $\\alpha$-enhancement traced by [Mg/Fe] all increase with galaxy stellar mass or velocity dispersion. We use one-zone galactic chemical evolution (GCE) models with a flexible star formation history (SFH) to model the age, [Mg/H], and [Mg/Fe] inferred from simple stellar population (SSP) fits to observed ellipticals at $z \\sim 0$ and $z \\sim 0.7$. We show that an SSP fit to the spectrum computed from a full GCE model gives ages and abundances close to the light-weighted, logarithmically averaged values of the composite stellar population, <age>, <[Mg/H]>, and <[Mg/Fe]>. With supernova Mg and Fe yields fixed to values motivated by Milky Way stellar populations, we find that predicted <[Mg/H]>-<age> and <[Mg/Fe]>-<age> relations are surprisingly insensitive to SFH parameters: older galaxies have higher <[Mg/Fe]>, but the detailed form of the SFH has limited impact. The star formation efficiency and outflow efficiency affect the early and late evolution of <[Mg/H]>, respectively; explaining observed trends requires higher star formation efficiency and lower outflows in more massive galaxies. With core collapse supernova yields calibrated to the plateau [Mg/Fe]$_{\\rm cc} \\approx0.45$ observed in many Milky Way studies, our models underpredict the observed <[Mg/Fe]> ratios of ellipticals by 0.05-0.1 dex. Increasing the core collapse yield ratio to [Mg/Fe]$_{\\rm cc} = 0.55$ improves the agreement, though the models still lie below the data. We discuss potential resolutions of this discrepancy, including the possibility that many ellipticals terminate their star formation with a self-enriching, terminating burst that reduces the light-weighted age and boosts <[Mg/Fe]>.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-07-10T18:10:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "elliptical galaxies",
      "chemical abundances",
      "core collapse yield ratio",
      "higher star formation efficiency",
      "core collapse supernova yields"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}