{
  "id": "2002.08516",
  "version": "v1",
  "published": "2020-02-20T01:21:08.000Z",
  "updated": "2020-02-20T01:21:08.000Z",
  "title": "The CGM at Cosmic Noon with KCWI: Outflows from a Star-forming Galaxy at $z=2.071$",
  "authors": [
    "Nikole M. Nielsen",
    "Glenn G. Kacprzak",
    "Stephanie K. Pointon",
    "Michael T. Murphy",
    "Christopher W. Churchill",
    "Romeel Davé"
  ],
  "comment": "23 pages, 9 figures, 5 tables. Submitted to ApJ 5 Sep 2019, resubmitted to ApJ 19 Feb 2020",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present the first results from our CGM at Cosmic Noon with KCWI program to study gas flows in the circumgalactic medium (CGM) at $z=2-3$. Combining the power of a high-resolution VLT/UVES quasar spectrum, an HST/ACS image, and integral field spectroscopy with Keck/KCWI, we detected Lya emission from a $3.7L_{\\ast}$ galaxy at $z_{\\rm gal}=2.0711$ associated with a Lyman limit system with weak MgII ($W_r(2796)=0.24$ Ang) in quasar field J143040$+$014939. The galaxy is best modeled as a star-forming (SFR$_{\\rm FUV}=37.8$ M$_{\\odot}$ yr$^{-1}$) clumpy edge-on disk ($i=85^{\\circ}$). The background quasar probes the galaxy at an impact parameter of $D=66$ kpc along the projected galaxy minor axis ($\\Phi=89^{\\circ}$). From photoionization modeling of the absorption system, which includes Lya, MgII, SiII, SiIII, SiIV, and CIV, we infer a total line-of-sight CGM metallicity of ${\\rm [Si/H]}=-1.5^{+0.4}_{-0.3}$. The absorption system is roughly kinematically symmetric about the galaxy redshift, with a full MgII velocity spread of $\\sim210$ km s$^{-1}$. Given the galaxy--quasar orientation, CGM metallicity, and gas kinematics, we interpret this gas as outflowing from the host galaxy. By modeling the absorption as a polar outflow cone, we find the gas is decelerating with radial velocity $V_{\\rm out}=100-350$ km s$^{-1}$ for half opening angles of $\\theta_0=20^{\\circ}-80^{\\circ}$. Assuming a constant $V_{\\rm out}$, it would take $\\sim190-650$ Myr for the gas to reach 66 kpc. The outflow is energetic, with a mass outflow rate of $\\dot{M}_{\\rm out}=45-51$ M$_{\\odot}$ yr$^{-1}$ and mass loading factor of $\\eta\\sim1.3$. We aim to build a sample of $\\sim50$ MgII absorber--galaxy pairs at this epoch to better understand gas flows when they are most actively building galaxies.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-02-20T01:21:08.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "cosmic noon",
      "star-forming galaxy",
      "better understand gas flows",
      "total line-of-sight cgm metallicity",
      "absorption system"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 23,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}