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

Kavli Affiliate: Saul A. Rappaport

| First 5 Authors: Iminhaji Ablimit, Philipp Podsiadlowski, Rosanne Di Stefano, Saul A. Rappaport, James Wicker

| Summary:

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.

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