{
  "id": "1706.01901",
  "version": "v1",
  "published": "2017-06-06T18:01:00.000Z",
  "updated": "2017-06-06T18:01:00.000Z",
  "title": "Evidence for sub-Chandrasekhar-mass progenitors of Type Ia supernovae at the faint end of the width-luminosity relation",
  "authors": [
    "Stéphane Blondin",
    "Luc Dessart",
    "D. John Hillier",
    "Alexei M. Khokhlov"
  ],
  "comment": "10 pages, 6 figures. Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.SR",
    "astro-ph.CO",
    "astro-ph.HE"
  ],
  "abstract": "The faster light-curve evolution of low-luminosity Type Ia supernovae (SNe Ia) suggests that they could result from the explosion of white dwarf (WD) progenitors below the Chandrasekhar mass ($M_{\\rm Ch}$). Here we present 1D non-LTE time-dependent radiative transfer simulations of pure central detonations of carbon-oxygen WDs with a mass ($M_\\rm{tot}$) between 0.88 M$_{\\odot}$ and 1.15 M$_{\\odot}$, and a $^{56}\\rm{Ni}$ yield between 0.08 M$_{\\odot}$ and 0.84 M$_{\\odot}$. Their lower ejecta density compared to $M_{\\rm Ch}$ models results in a more rapid increase of the luminosity at early times and an enhanced $\\gamma$-ray escape fraction past maximum light. Consequently, their bolometric light curves display shorter rise times and larger post-maximum decline rates. Moreover, the higher $M(^{56}\\rm{Ni})/M_\\rm{tot}$ ratio at a given $^{56}\\rm{Ni}$ mass enhances the temperature and ionization level in the spectrum-formation region for the less luminous models, giving rise to bluer colours at maximum light and a faster post-maximum evolution of the $B-V$ colour. For sub-$M_{\\rm Ch}$ models fainter than $M_B\\approx -18.5$ mag at peak, the greater bolometric decline and faster colour evolution lead to a larger $B$-band post-maximum decline rate, $\\Delta M_{15}(B)$. In particular, all of our previously-published $M_{\\rm Ch}$ models (standard and pulsational delayed detonations) are confined to $\\Delta M_{15}(B) < 1.4$ mag, while the sub-$M_{\\rm Ch}$ models with $M_\\rm{tot}\\lesssim 1$ M$_{\\odot}$ extend beyond this limit to $\\Delta M_{15}(B)\\approx 1.65$ mag for a peak $M_B\\approx -17$ mag, in better agreement with the observed width-luminosity relation (WLR). Regardless of the precise ignition mechanism, these simulations suggest that fast-declining SNe Ia at the faint end of the WLR could result from the explosion of WDs whose mass is significantly below the Chandrasekhar limit.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-06-06T18:01:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "type ia supernovae",
      "faint end",
      "width-luminosity relation",
      "sub-chandrasekhar-mass progenitors",
      "display shorter rise times"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}