Signatures of a surviving helium-star companion in Type Ia supernovae and constraints on the progenitor companion of SN 2011fe

TL;DR

This study models the long-term evolution of helium-star companions surviving Type Ia supernovae to identify observational signatures, concluding that such companions are unlikely in the case of SN 2011fe.

Contribution

It introduces a method to predict post-impact properties of surviving helium-star companions using hydrodynamical and stellar evolution simulations, aiding future observational searches.

Findings

Surviving He-star companions become more luminous than SN 2011fe about 1000 days after maximum light.

Comparison with SN 2011fe's light curve suggests He-star companions are unlikely for this supernova.

The model provides constraints on the nature of progenitor systems for Type Ia supernovae.

Abstract

Single-degenerate (SD) binary systems composed of a white dwarf and a non-degenerate helium (He)-star companion have been proposed as the potential progenitors of Type Ia supernovae (SNe Ia). The He-star companions are expected to survive the SN Ia explosion in this SD progenitor model. In the present work, we map the surviving He-star companion models computed from our previous three-dimensional hydrodynamical simulations of ejecta-companion interaction into the one-dimensional stellar evolution code MESA to follow their long-term evolution to make predictions on their post-impact observational properties, which can be helpful for searches of such surviving He-star companions in future observations. By comparing with the very late-epoch light curve of the best observed SN Ia, SN 2011fe, we find that our surviving He-star companions become significantly more luminous than SN 2011fe about 1000d after the maximum light. This suggests that a He star is very unlikely to be a companion to the progenitor of SN 2011fe.