The early detection and follow-up of the highly obscured Type II supernova 2016ija/DLT16am

TL;DR

This paper analyzes the highly obscured Type II supernova 2016ija, providing detailed photometric and spectroscopic data, revealing its fast decline, high extinction, and confirming its consistency with known supernova luminosity-velocity relations.

Contribution

It presents the first detailed analysis of SN 2016ija, including its extinction, light curve, and spectral features, expanding understanding of obscured Type II supernovae.

Findings

SN 2016ija is highly extincted with E(B-V)=1.95 mag.

It exhibits a fast rise and short plateau typical of fast declining Type II supernovae.

Its luminosity and velocity are consistent with existing Type II supernova relations.

Abstract

We present our analysis of the Type II supernova DLT16am (SN~2016ija). The object was discovered during the ongoing $\rm{D}<40\,\rm{Mpc}$ (DLT40) one day cadence supernova search at $r\sim20.1\,\rm{mag}$ in the `edge-on' nearby ($D=20.0\pm1.9\,\rm{Mpc}$) galaxy NGC~1532. The subsequent prompt and high-cadenced spectroscopic and photometric follow-up revealed a highly extincted transient, with $E(B-V)=1.95\pm0.15\,\rm{mag}$, consistent with a standard extinction law with $R_V=3.1$ and a bright ($M_V=-18.49\pm0.65\,\rm{mag}$) absolute peak-magnitude. The comparison of the photometric features with those of large samples of Type II supernovae reveals a fast rise for the derived luminosity and a relatively short plateau phase, with a slope of $S_{50V}=0.84\pm0.04\,\rm{mag}/50\,\rm{d}$ consistent with the photometric properties typical of those of fast declining Type II supernovae. Despite the large uncertainties on the distance and the extinction in the direction of DLT16am, the measured photospheric expansion velocity and the derived absolute $V$-band magnitude at $\sim50\,\rm{d}$ after the explosion match the existing luminosity-velocity relation for Type II supernovae.