The type Iax supernova, SN 2015H: a white dwarf deflagration candidate

TL;DR

This paper presents detailed observations of the type Iax supernova SN 2015H, compares it with deflagration models of white dwarfs, and suggests the explosion leaves behind a bound remnant.

Contribution

It provides one of the most comprehensive observational datasets for SN 2015H and compares these with deflagration models, proposing a bound remnant after explosion.

Findings

SN 2015H peaked at M_r = -17.27 mag

Ejected approximately 0.6 solar masses of material

Model light curves evolve faster than observed

Abstract

We present results based on observations of SN 2015H which belongs to the small group of objects similar to SN 2002cx, otherwise known as type Iax supernovae. The availability of deep pre-explosion imaging allowed us to place tight constraints on the explosion epoch. Our observational campaign began approximately one day post-explosion, and extended over a period of about 150 days post maximum light, making it one of the best observed objects of this class to date. We find a peak magnitude of M$_r$ = -17.27 $\pm$ 0.07, and a ($\Delta m_{15})_r$ = 0.69 $\pm$ 0.04. Comparing our observations to synthetic spectra generated from simulations of deflagrations of Chandrasekhar mass carbon-oxygen white dwarfs, we find reasonable agreement with models of weak deflagrations that result in the ejection of ~0.2 M$_{\odot}$ of material containing ~0.07 M$_{\odot}$ of 56Ni. The model light curve however, evolves more rapidly than observations, suggesting that a higher ejecta mass is to be favoured. Nevertheless, empirical modelling of the pseudo-bolometric light curve suggests that $\lesssim$0.6 M_sun of material was ejected, implying that the white dwarf is not completely disrupted, and that a bound remnant is a likely outcome.