3D deflagration simulations leaving bound remnants: a model for 2002cx-like Type Ia supernovae

TL;DR

This study presents 3D deflagration simulations of a white dwarf that reproduce the observed features of 2002cx-like supernovae, including bound remnants, offering insights into their explosion mechanism and observational signatures.

Contribution

It introduces a detailed 3D deflagration model that successfully matches observations of 2002cx-like supernovae and predicts the existence of bound remnants.

Findings

Model reproduces optical and near-infrared features of SN 2005hk.

Simulation leaves behind a bound remnant of about 1.03 solar masses.

Bound remnant consists mainly of unburned C/O and some fallback material.

Abstract

2002cx-like supernovae are a sub-class of sub-luminous Type Ia supernovae. Their light curves and spectra are characterized by distinct features that indicate strong mixing of the explosion ejecta. Pure turbulent deflagrations have been shown to produce such mixed ejecta. Here, we present hydrodynamics, nucleosynthesis and radiative transfer calculations for a 3D full-star deflagration of a Chandrasekhar-mass white dwarf. Our model is able to reproduce the characteristic observational features of SN 2005hk (a proto-typical 2002cx-like supernova), not only in the optical, but also in the near-infrared. For that purpose we present, for the first time, five near-infrared spectra of SN 2005hk from -0.2 to 26.6 days with respect to B-band maximum. Since our model burns only small parts of the initial white dwarf, it fails to completely unbind the white dwarf and leaves behind a bound remnant of ~1.03 solar masses -- consisting mainly of unburned carbon and oxygen, but also enriched by some amount of intermediate-mass and iron-group elements from the explosion products that fall back on the remnant. We discuss possibilities for detecting this bound remnant and how it might influence the late-time observables of 2002cx-like SNe.