{
  "id": "2410.23349",
  "version": "v1",
  "published": "2024-10-30T18:00:04.000Z",
  "updated": "2024-10-30T18:00:04.000Z",
  "title": "NGDEEP: The Star Formation and Ionization Properties of Galaxies at $1.7 < z < 3.4$",
  "authors": [
    "Lu Shen",
    "Casey Papovich",
    "Jasleen Matharu",
    "Nor Pirzkal",
    "Weida Hu",
    "Danielle A. Berg",
    "Micaela B. Bagley",
    "Bren E. Backhaus",
    "Nikko J. Cleri",
    "Mark Dickinson",
    "Steven L. Finkelstein",
    "Nimish P. Hathi",
    "Marc Huertas-Company",
    "Taylor A. Hutchison",
    "Mauro Giavalisco",
    "Norman A. Grogin",
    "Anne E. Jaskot",
    "Intae Jung",
    "Jeyhan S. Kartaltepe",
    "Anton M. Koekemoer",
    "Jennifer M. Lotz",
    "Pablo G. Pérez-González",
    "Barry Rothberg",
    "Raymond C. Simons",
    "Brittany N. Vanderhoof",
    "L. Y. Aaron Yung"
  ],
  "comment": "27 pages, 14 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We use JWST/NIRISS slitless spectroscopy from the Next Generation Deep Extragalactic Exploratory Public (NGDEEP) Survey to investigate the physical condition of star-forming galaxies at $1.7 < z < 3.4$. At these redshifts, the deep NGDEEP NIRISS slitless spectroscopy covers the [O II]$\\lambda\\lambda$3726,3729, [O III]$\\lambda\\lambda$4959,5007, H$\\beta$ and H$\\alpha$ emission features for galaxies with stellar masses $\\log(\\mathrm{M_\\ast/M_\\odot}) \\gtrsim 7$, nearly a factor of a hundred lower than previous studies. We focus on the [O III]/[O II] (O$_{32}$) ratio which is primarily sensitive to the ionization state and with a secondary dependence on the gas-phase metallicity of the interstellar medium. We find significant ($\\gtrsim5\\sigma$) correlations between the O$_{32}$ ratio and galaxy properties as O$_{32}$ increases with decreasing stellar mass, decreasing star formation rate (SFR), increasing specific SFR (sSFR$\\equiv \\mathrm{SFR}/M_*$), and increasing equivalent width (EW) of H$\\beta$ and H$\\alpha$. These trends suggest a tight connection between the ionization parameter and these galaxy properties. Galaxies at $z\\sim2-3$ exhibit a higher O$_{32}$ than local normal galaxies with the same stellar masses and SFRs, indicating that they have a higher ionization parameter and lower metallicity than local normal galaxies. In addition, we observe an evolutionary trend in the O$_{32}$ -- EW(H$\\beta$) relation from $z\\sim0$ and $z\\gtrsim5$, such that higher redshift galaxies have higher EW(H$\\beta$) and higher O$_{32}$ at fixed EW. We argue that both the enhanced recent star formation activity and the higher star formation surface density may contribute to the increase in O$_{32}$ and the ionization parameter.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-10-30T18:00:04.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "ionization properties",
      "ngdeep niriss slitless spectroscopy",
      "niriss slitless spectroscopy covers",
      "ionization parameter",
      "stellar mass"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 27,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}