Self-shielding of Soft X-rays in SN Ia Progenitors

TL;DR

This paper investigates how circumstellar matter can obscure soft X-ray emissions from SN Ia progenitors, explaining the scarcity of observed super soft X-ray sources despite their expected prevalence.

Contribution

It quantifies the circumstellar matter needed to hide soft X-ray sources and assesses the likelihood of detecting such sources in UV surveys, providing insights into SN Ia progenitor environments.

Findings

Circumstellar matter can obscure soft X-ray emissions in SN Ia progenitors.

Fewer than 100 such sources are expected to be detectable in GALEX survey.

Obscuring matter likely has a large, non-spherical covering factor.

Abstract

There are insufficient super soft (~ 0.1 keV) X-ray sources in either spiral or elliptical galaxies to account for the rate of explosion of Type Ia supernovae in either the single degenerate or the double degenerate scenarios. We quantify the amount of circumstellar matter that would be required to suppress the soft X-ray flux by yielding a column density in excess of 10^{23} cm^{-2}. We summarize evidence that appropriate quantities of matter are extant in SN Ia and in recurrent novae that may be supernova precursors. The obscuring matter is likely to have a large, but not complete, covering factor and to be substantially non-spherically symmetric. Assuming that much of the absorbed X-ray flux is re-radiated as black-body radiation in the UV, we estimate that fewer than 100 sources might be detectable in the GALEX all sky survey.