Pre-explosion companion stars in Type Iax supernovae

TL;DR

This paper models pre-explosion companion stars in Type Iax supernovae to help identify their progenitors, finding that a hybrid white dwarf and helium star scenario best explains observations of SN 2012Z-S1.

Contribution

It introduces detailed binary evolution calculations to predict pre-explosion properties of companion stars in SNe Iax, aiding progenitor identification from observations.

Findings

Hybrid WD+He star scenario is most consistent with SN 2012Z-S1 observations.

Non-degenerate helium companions can explain pre-explosion features.

Models support helium star companions as likely progenitors.

Abstract

Type Iax supernovae (SNe Iax) are proposed as one new sub-class of SNe Ia since they present observational properties that are sufficiently distinct from the bulk of SNe Ia. SNe Iax are the most common of all types of peculiar SNe by both number and rate, with an estimated rate of occurrence of about 5-30% of the total SN Ia rate. However, the progenitor systems of SNe Iax are still uncertain. Analyzing pre-explosion images at SN Iax positions provides a direct way to place strong constraints on the nature of progenitor systems of SNe Iax. In this work, we predict pre-explosion properties of binary companion stars in a variety of potential progenitor systems by performing detailed binary evolution calculations with the one-dimensional stellar evolution code STARS. This will be helpful for constraining progenitor systems of SNe Iax from their pre-explosion observations. With our binary evolution calculations, it is found that the non-degenerate helium (He) companion star to both a massive C/O WD (> 1.1 solar mass) and a hybrid C/O/Ne WD can provide an explanation for the observations of SN~2012Z-S1, but the hybrid WD+He star scenario is more favorable.