Upper limits on bolometric luminosities of ten type Ia supernova progenitors from Chandra observations

TL;DR

This study uses pre-explosion Chandra X-ray observations to set upper limits on the luminosities of type Ia supernova progenitors, challenging the super-soft source model for some cases and suggesting alternative progenitor scenarios.

Contribution

It provides the first set of upper limits on progenitor luminosities for ten nearby type Ia supernovae, constraining the super-soft source progenitor hypothesis.

Findings

Two supernovae have progenitor luminosity limits below the brightest super-soft sources.

For SN2011fe, systems at Eddington luminosity with temperatures as low as 40 eV are ruled out.

Results align with statistical studies indicating progenitors may not be classical super-soft sources.

Abstract

We present an analysis of Chandra observations of the position of ten nearby (< 25 Mpc) type Ia supernovae, taken before the explosions. No sources corresponding to progenitors were found in any of the observations. We calculated upper limits on the bolometric luminosities of the progenitors assuming black-body X-ray spectra with temperatures of 30-150 eV. This is inspired by the fact that luminous super-soft X-ray sources have been suggested as the direct progenitors of type Ia supernovae. The upper limits of two supernovae in our sample are comparable to the luminosities of the brightest observed super-soft sources, ruling out such sources as the progenitors of these supernovae. In contrast to Liu et al (2012) we find that for SN2011fe we can rule out Eddington luminosity systems for black body temperatures as low as 40 eV. Our findings are consistent with statistical studies comparing the observed type Ia supernova rate to the number of super-soft sources or the integrated X-ray luminosity in external galaxies. This suggest that either the progenitors of type Ia supernovae are not accreting, nuclear burning white dwarfs, or that they do not look like the classical super-soft sources, e.g. because they are obscured.