X-ray limits on the progenitor system of the Type Ia supernova 2017ejb

Charles D. Kilpatrick*, David A. Coulter, Georgios Dimitriadis, Ryan J. Foley, David O. Jones, Yen Chen Pan, Anthony L. Piro, Armin Rest, César Rojas-Bravo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We present deep X-ray limits on the presence of a pre-explosion counterpart to the lowluminosity Type Ia supernova (SN Ia) 2017ejb. SN 2017ejb was discovered in NGC 4696, a well-studied elliptical galaxy in the Centaurus cluster with 894 ks of Chandra imaging between 14 and 3 yr before SN 2017ejb was discovered. Using post-explosion photometry and spectroscopy of SN 2017ejb, we demonstrate that SN 2017ejb is most consistent with low-luminosity SNe Ia such as SN 1986G and SN 1991bg. Analysing the location of SN 2017ejb in pre-explosion images, we do not detect a pre-explosion X-ray source.We use these data to place upper limits on the presence of any unobscured supersoft X-ray source (SSS). SSS systems are known to consist of white dwarfs (WDs) accreting from a non-degenerate companion star. We rule out any source similar to known SSS systems with kTeff > 85 eV and Lbol > 4 × 1038 erg s-1 as well as models of stably accreting Chandrasekhar-mass WDs with accretion rates M > 3 × 10-7M yr-1. These findings suggest that low-luminosity SNe Ia similar to SN 2017ejb explode from WDs that are low-mass, have low pre-explosion accretion rates, or accrete very soon before explosion. Based on the limits from SN 2017ejb and other nearby SNe Ia, we infer that < 47 per cent of SNe Ia explode in stably accreting Chandrasekhar-mass SSS systems.

Original languageEnglish (US)
Pages (from-to)4123-4132
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Dec 11 2018


  • Supernovae: general
  • Supernovae: individual: SN 2017ejb
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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