SN 2020sck: deflagration in a carbon-oxygen white dwarf

TL;DR

This paper studies SN 2020sck, a type Iax supernova, using photometry and spectroscopy, and finds evidence of a carbon-oxygen white dwarf explosion with specific nickel and ejecta masses, supporting a deflagration model.

Contribution

It provides detailed observational analysis and modeling of SN 2020sck, confirming a pure deflagration explosion in a C-O white dwarf with specific synthesized nickel and ejecta masses.

Findings

SN 2020sck has Δm_B(15) = 2.03 mag and M_B = -17.81 mag.

Spectroscopic features indicate unburned C and O, consistent with a C-O white dwarf.

Modeling suggests 0.16 M_sun of Ni-56 and 0.37 M_sun of ejecta were produced.

Abstract

We present optical UBVRI photometry and low-to-medium resolution spectroscopic observations of type Iax SN 2020sck spanning -5.5 d to +67 d from maximum light in the B-band. From the photometric analysis we find $\Delta m_{\rm{B}}$(15) = 2.03$\pm$0.05 mag and $M_{\rm{B}}$=-17.81$\pm$0.22 mag. Radiation diffusion model fit to the quasi-bolometric light curve indicates 0.13$\pm$0.02 $M_{\odot}$ of $^{56}$Ni and 0.34 $M_{\rm \odot}$ of ejecta are synthesized in the explosion. Comparing the observed quasi-bolometric light curve with angle-averaged bolometric light curve of three-dimensional pure deflagration explosion of $M_{\rm{ch}}$ carbon-oxygen white dwarf, we find agreement with a model in which 0.16 $M_{\odot}$ of $^{56}$Ni and 0.37 $M_{\odot}$ of ejecta is formed. By comparing the +1.4 day spectrum of SN 2020sck with synthetic spectrum generated using SYN++, we find absorption features due to C II, C III and O I. These are unburned materials in the explosion and indicate a C-O white dwarf. One dimensional radiative transfer modeling of the spectra with TARDIS shows higher density in the ejecta near the photosphere and a steep decrease in the outer layers with an ejecta composition dominated mostly by C, O, Si, Fe, and Ni. The star formation rate of the host galaxy computed from the luminosity of the H$\alpha$ ($\lambda$6563) line is 0.09 $M_{\odot}$ yr$^{-1}$ indicating a relatively young stellar environment.