White dwarf -- red giant star binaries as Type Ia supernova progenitors: with and without magnetic confinement

TL;DR

This study investigates how magnetic confinement in white dwarf--red giant binaries influences their evolution and potential to produce Type Ia supernovae, expanding understanding of this progenitor channel.

Contribution

It introduces the role of magnetic confinement in white dwarf accretion, showing how it alters the parameter space for Type Ia supernova progenitors in symbiotic systems.

Findings

Magnetic confinement shifts the initial parameter space towards shorter orbital periods.

Confined accretion enhances hydrogen burning efficiency, reducing nova outbursts.

The study provides predictions for observable remnants in supernova remnants.

Abstract

Various white-dwarf (WD) binary scenarios have been proposed trying to understand the nature and the diversity of Type Ia supernovae (SNe Ia). In this work, we study the evolution of carbon-oxygen WD -- red giant (RG) binaries (including the role of magnetic confinement) as possible SN Ia progenitors (the so-called symbiotic progenitor channel). Using the \textsc{mesa} stellar evolution code, we calculate the time dependence of the structure of the RG star, the wind mass loss, the Roche-lobe-overflow (RLOF) mass-transfer rate, the polar mass-accretion rate (in the case of magnetic confinement), and the orbital and angular-momentum evolution. We consider cases where the WD is non-magnetic and cases where the magnetic field is strong enough to force accretion onto the two small polar caps of the WD. Confined accretion onto a small area allows for more efficient hydrogen burning, potentially suppressing nova outbursts. This makes it easier for the WD to grow in mass towards the Chandrasekhar mass limit and explode as a SN Ia. With magnetic confinement, the initial parameter space of the symbiotic channel for SNe Ia is shifted towards shorter orbital periods and lower donor masses compared to the case without magnetic confinement. Searches for low-mass He WDs or relatively low-mass giants with partially stripped envelopes that survived the supernova explosion and are found in SN remnants will provide crucial insights for our understanding of the contribution of this symbiotic channel.