Wait for it: Post-supernova winds driven by delayed radioactive decays

TL;DR

This paper investigates how delayed radioactive decays in ionized white dwarfs can drive winds that influence late-time supernova observations, providing insights into the nature of surviving remnants after Type Ia and Iax supernovae.

Contribution

It introduces models of post-supernova winds driven by delayed radioactive decays in surviving white dwarfs, linking these winds to observable late-time supernova features and progenitor scenarios.

Findings

Post-SN Ia models conflict with late-time SN 2011fe observations.

Post-SN Iax models better match observations, supporting deflagration progenitors.

Delayed decay-driven winds can significantly affect late-time supernova appearance.

Abstract

In most astrophysical situations, the radioactive decay of 56Ni to 56Co occurs via electron capture with a fixed half-life of 6.1 days. However, this decay rate is significantly slowed when the nuclei are fully ionized because K-shell electrons are unavailable for capture. In this paper, we explore the effect of these delayed decays on white dwarfs (WDs) that may survive Type Ia and Type Iax supernovae (SNe Ia and SNe Iax). The energy released by the delayed radioactive decays of 56Ni and 56Co drives a persistent wind from the surviving WD's surface that contributes to the late-time appearance of these SNe after emission from the bulk of the SN ejecta has faded. We use the stellar evolution code MESA to calculate the hydrodynamical evolution and resulting light curves of these winds. Our post-SN Ia models conflict with late-time observations of SN 2011fe, but uncertainties in our initial conditions prevent us from ruling out the existence of surviving WD donors. Much better agreement with observations is achieved with our post-SN Iax bound remnant models, providing evidence that these explosions are due to deflagrations in accreting WDs that fail to completely unbind the WDs. Future radiative transfer calculations and wind models utilizing explosion simulations for more accurate initial conditions will extend our study of radioactively-powered winds from post-SN surviving WDs and enable their use as powerful discriminants among the various SN Ia and SN Iax progenitor scenarios.