Impact of convective overshooting on the single-degenerate model of Type Ia supernovae

TL;DR

This study examines how convective overshooting influences the parameter space and birth rate of Type Ia supernovae in the single-degenerate model, using the CEW model and MESA simulations to reveal significant effects on progenitor characteristics.

Contribution

It introduces the impact of convective overshooting on the SD model's parameter space and SN Ia birth rate, highlighting non-monotonic variations and implications for SNe Ia-CSM.

Findings

Convective overshooting expands the parameter space for massive white dwarf progenitors.

The SN Ia birth rate varies non-monotonically with overshooting parameters.

The model can account for SNe Ia interacting with circumstellar medium (CSM).

Abstract

The single-degenerate (SD) model is one of the principal models for the progenitors of Type Ia supernovae (SNe Ia). However, it faces some challenges, the primary being its inability to account for the observed SN Ia birth rate. Many studies have attempted to address this issue by expanding the parameter space, defined by the initial donor star mass and orbital period, that can lead to SNe Ia, as well as by improving binary population synthesis. While these efforts have led to significant progress, many uncertainties in stellar physics persist, which influences the outcomes of such studies. Convective overshooting, which can significantly affect the internal structure of a star and subsequently its evolution within a binary system, is one of the most significant sources of uncertainty in stellar physics. We investigate the effect of convective overshooting on the parameter space and birth rate of SNe Ia within the SD model. We employed the common-envelope wind (CEW) model, a new version of the SD model, as our progenitor model. Using MESA, we obtained the parameter space that leads to SNe Ia for three different convective overshooting parameters and calculated the corresponding SN Ia birth rate. Convective overshooting expands the upper boundaries (corresponding to a larger initial donor mass) and right boundaries (corresponding to a longer initial orbital period) of the parameter space for systems with massive white dwarfs (WDs; >= 0.75Msun). However, the minimum WD mass and the parameter space for low-mass WDs - and, consequently, the calculated SN Ia birth rate - vary non-monotonically with convective overshooting parameters. The CEW model may explain the SNe Ia that interact with the circumstellar medium (CSM), i.e., SNe Ia-CSM. We find that the parameter space for SNe Ia-CSM increases with convective overshooting parameters, as does their birth rate.