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

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


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


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