{
  "id": "1909.05267",
  "version": "v1",
  "published": "2019-09-11T18:00:13.000Z",
  "updated": "2019-09-11T18:00:13.000Z",
  "title": "Variable H$α$ Emission in the Nebular Spectra of the Low-Luminosity Type Ia SN2018cqj/ATLAS18qtd",
  "authors": [
    "Jose L. Prieto",
    "Ping Chen",
    "Subo Dong",
    "S. Bose",
    "A. Gal-Yam",
    "T. W. -S. Holoien",
    "J. A. Kollmeier",
    "M. M. Phillips",
    "B. J. Shappee"
  ],
  "comment": "submitted to AAS journals",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "We present optical photometry and spectroscopy of the Type Ia supernova SN2018cqj/ATLAS18qtd. The supernova exploded in an isolated region at $\\sim 65$ kpc from the S0 galaxy IC 550 at $z=0.0165$ ($D\\approx 74$ Mpc) and has a redshift consistent with a physical association to this galaxy. Multicolor photometry show that SN2018cqj/ATLAS18qtd is a low-luminosity ($M_{B_{max}}\\approx -17.9$ mag), fast-declining Type Ia with color stretch $s_{BV} \\approx 0.6$ and $B$-band decline rate $\\Delta m_{15}(B) \\approx 1.77$ mag. Two nebular-phase spectra obtained as part of the 100IAS survey at +193 and +307 days after peak show the clear detection of a narrow H$\\alpha$ line in emission that is resolved in the first spectrum with $\\rm FWHM \\approx 1200$ km s$^{-1}$ and $L_{H\\alpha} \\approx 3.8\\times 10^{37}$ erg s$^{-1}$. The detection of a resolved H$\\alpha$ line with a declining luminosity is broadly consistent with recent models where hydrogen is stripped from the non-degenerate companion in a single-degenerate progenitor system. The amount of hydrogen consistent with the luminosities of the H$\\alpha$ line would be $\\sim 10^{-3}$ M$_{\\odot}$, significantly less than theoretical model predictions in the classical single-degenerate progenitor systems. SN2018cqj/ATLAS18qtd is the second low-luminosity, fast-declining Type Ia SN in the 100IAS survey after SN2018fhw/ASASSN-18tb that shows narrow H$\\alpha$ in emission in its nebular-phase spectra.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-09-11T18:00:13.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "low-luminosity type ia sn2018cqj/atlas18qtd",
      "nebular spectra",
      "single-degenerate progenitor system",
      "fast-declining type ia",
      "type ia supernova sn2018cqj/atlas18qtd"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}