Impact of type ia supernova ejecta on binary companions in the single-degenerate scenario

TL;DR

This study uses advanced simulations to analyze how Type Ia supernova ejecta impact binary companions in the single-degenerate scenario, revealing details about mass loss, contamination, and rotational changes.

Contribution

It provides the first detailed multi-dimensional simulation of supernova impact on various companion types, including effects of orbital motion and rotation, with new insights into unbinding processes and contamination levels.

Findings

Unbound mass and kick velocity follow power-law relations with binary separation.

Ablation dominates the unbinding process, contrary to previous assumptions.

Contamination levels vary significantly among companion types, with the MS star showing potential as a progenitor candidate.

Abstract

Type Ia supernovae are thought to be caused by thermonuclear explosions of a carbon-oxygen white dwarf in close binary systems. In the single-degenerate scenario (SDS), the companion star is non-degenerate and can be significantly affected by the explosion. We explore this interaction by means of multi-dimensional adaptive mesh refinement simulations using the FLASH code. We consider several different companion types, including main-sequence-like stars (MS), red giants (RG), and helium stars (He). In addition, we include the symmetry-breaking effects of orbital motion, rotation of the non-degenerate star, and Roche-lobe overflow. A detailed study of a sub-grid model for Type Ia supernovae is also presented. We find that the dependence of the unbound stellar mass and kick velocity on the initial binary separation can be fitted by power-law relations. By using the tracer particles in FLASH, the process leading to the unbinding of matter is dominated by ablation, which has usually been neglected in past analytical studies. The level of Ni/Fe contamination of the companion that results from the passage of the supernova ejecta is found to be a $\sim 10^{-5} M_{\odot}$ for the MS star, $\sim 10^{-4} M_{\odot}$ for the He star, and $\sim 10^{-8} M_{\odot}$ for the RG. The spinning MS companion star loses about half of its initial angular momentum during the impact, causing the rotational velocity to drop to a quarter of the original rotational velocity, suggesting that the Tycho G star is a promising progenitor candidate in the SDS.