SN2002es-like Supernovae From Different Viewing Angles

TL;DR

This study compares optical light curves of two SN2002es-like supernovae, revealing how viewing angles influence early emission features and suggesting a common progenitor with different observational signatures.

Contribution

It demonstrates that viewing angle affects early light curve behavior and emission signatures in SN2002es-like supernovae, highlighting the role of supernova-companion interaction.

Findings

iPTF14atg shows a slow, steady rise over 22 days.

iPTF14dpk exhibits a rapid initial rise then slower increase.

Emission before -17 days is due to supernova-companion collision.

Abstract

In this letter, we compare optical light curves of two SN2002es-like Type Ia supernovae, iPTF14atg and iPTF14dpk, from the intermediate Palomar Transient Factory. Although the two light curves resemble each other around and after maximum, they show distinct early-phase rise behavior in the $\textit{r}$-band. On the one hand, iPTF14atg revealed a slow and steady rise which lasted for 22 days with a mean rise rate of $0.2\sim0.3\,\textrm{mag}\,\textrm{day}^{-1}$, before it reached the $R$-band peak ($-18.05\,$mag). On the other hand, iPTF14dpk rose rapidly to $-17\,$mag within a day of discovery with a rise rate $>1.8\,\textrm{mag}\,\textrm{day}^{-1}$, and then rose slowly to its peak ($-18.19\,$mag) with a rise rate similar to iPTF14atg. The apparent total rise time of iPTF14dpk is therefore only 16 days. We show that emission from iPTF14atg before $-17\,$days with respect to its maximum can be entirely attributed to radiation produced by collision between the SN and its companion star. Such emission is absent in iPTF14dpk probably because of an unfavored viewing angle, provided that SN2002es-like events arise from the same progenitor channel. We further show that a SN2002es-like SN may experience a dark phase after the explosion but before its radioactively powered light curve becomes visible. This dark phase may be hidden by radiation from supernova-companion interaction.