Intermediate Luminosity Type Iax SN 2019muj With Narrow Absorption Lines: Long-Lasting Radiation Associated With a Possible Bound Remnant Predicted by the Weak Deflagration Model

TL;DR

This study analyzes SN 2019muj, revealing long-lasting radiation and narrow absorption lines, supporting the weak deflagration model with a bound remnant as a common explosion mechanism for Type Iax supernovae.

Contribution

It provides detailed spectroscopic and photometric analysis of SN 2019muj, linking its features to the weak deflagration model and suggesting a unified explosion mechanism for SNe Iax.

Findings

SN 2019muj shares characteristics with subluminous SNe Iax 2008ha and 2010ae.

Late-time light curve flattening indicates a bound white dwarf remnant.

Weak deflagration model reproduces late-phase light curves across SNe Iax.

Abstract

We present comprehensive spectroscopic and photometric analyses of the intermediate luminosity Type Iax supernova (SN Iax) 2019muj based on multi-band datasets observed through the framework of the OISTER target-of-opportunity program. SN 2019muj exhibits almost identical characteristics with the subluminous SNe Iax 2008ha and 2010ae in terms of the observed spectral features and the light curve evolution at the early phase, except for the peak luminosity. The long-term observations unveil the flattening light curves at the late time as seen in a luminous SN Iax 2014dt. This can be explained by the existence of an inner dense and optically-thick component possibly associated with a bound white dwarf remnant left behind the explosion. We demonstrate that the weak deflagration model with a wide range of the explosion parameters can reproduce the late-phase light curves of other SNe Iax. Therefore, we conclude that a common explosion mechanism operates for different subclass SNe Iax.