SN 2020udy: A new piece of the homogeneous bright group in the diverse Iax subclass

TL;DR

SN 2020udy, a bright type Iax supernova, exhibits spectral and light curve features consistent with deflagration of a Carbon-Oxygen white dwarf, with detailed spectral analysis revealing ejecta stratification and chemical mixing.

Contribution

This study provides detailed optical observations and spectral modeling of SN 2020udy, highlighting its similarities to bright Iax supernovae and offering insights into its explosion mechanism.

Findings

SN 2020udy synthesized about 0.08 solar masses of $^{56}$Ni.

Spectral features show weak Si II lines and dominance of Iron Group Elements at late times.

Spectral modeling suggests ejecta stratification and chemical mixing.

Abstract

We present optical observations and analysis of a bright type Iax SN~2020udy hosted by NGC 0812. The light curve evolution of SN~2020udy is similar to other bright Iax SNe. Analytical modeling of the quasi bolometric light curves of SN 2020udy suggests that 0.08$\pm$0.01 M$_{\odot}$ of $^{56}$Ni would have been synthesized during the explosion. Spectral features of SN 2020udy are similar to the bright members of type Iax class showing weak Si {\sc II} line. The late-time spectral sequence is mostly dominated by Iron Group Elements (IGEs) with broad emission lines. Abundance tomography modeling of the spectral time series of SN~2020udy using TARDIS indicates stratification in the outer ejecta, however, to confirm this, spectral modeling at a very early phase is required. After maximum light, uniform mixing of chemical elements is sufficient to explain the spectral evolution. Unlike the case of normal type Ia SNe, the photospheric approximation remains robust until +100 days, requiring an additional continuum source. Overall, the observational features of SN 2020udy are consistent with the deflagration of a Carbon-Oxygen white dwarf.