Type Iax SNe as a few-parameter family

TL;DR

This study models five Type Iax supernovae using spectral fitting to reveal a common internal structure, challenging the pure deflagration model predictions and suggesting a unified origin for this supernova class.

Contribution

It introduces a stratified abundance model for Type Iax SNe, contrasting with the well-mixed profiles predicted by previous deflagration models.

Findings

Stratified chemical structure contradicts pure deflagration models.

A template model atmosphere can describe the entire class.

All SNe Iax likely share a similar internal structure.

Abstract

We present direct spectroscopic modeling of five Type Iax supernovae (SNe) with the one dimensional Monte Carlo radiative transfer code TARDIS. The abundance tomography technique is used to map the chemical structure and physical properties of the SN atmosphere. Through via fitting of multiple spectral epochs with self-consistent ejecta models, we can then constrain the location of some elements within the ejecta. The synthetic spectra of the best-fit models are able to reproduce the flux continuum and the main absorption features in the whole sample. We find that the mass fractions of IGEs and IMEs show a decreasing trend toward the outer regions of the atmospheres using density profiles similar to those of deflagration models in the literature. Oxygen is the only element, which could be dominant at higher velocities. The stratified abundance structure contradicts the well-mixed chemical profiles predicted by pure deflagration models. Based on the derived densities and abundances, a template model atmosphere is created for the SN Iax class and compared to the observed spectra. Free parameters are the scaling of the density profile, the velocity shift of the abundance template, and the peak luminosity. The results of this test support the idea that all SNe Iax can be described by a similar internal structure, which argues for a common origin of this class of explosions.