Single or Double Degenerate Progenitors? Searching for Shock Emission in the SDSS-II Type Ia Supernovae

TL;DR

This study searches for shock emission signatures in early light curves of Type Ia supernovae from SDSS-II data, finding no evidence but setting limits on companion star properties, thus constraining progenitor models.

Contribution

It provides the first systematic search for shock signatures in a large, well-observed sample of SNe Ia and establishes upper limits on shock emission and companion star characteristics.

Findings

No evidence of shock emission detected in the sample.

Placed an upper limit on shock amplitude at 9% of peak flux.

Constraints on companion star mass, disfavoring red giant companions.

Abstract

From the set of nearly 500 spectroscopically confirmed type~Ia supernovae and around 10,000 unconfirmed candidates from SDSS-II, we select a subset of 108 confirmed SNe Ia with well-observed early-time light curves to search for signatures from shock interaction of the supernova with a companion star. No evidence for shock emission is seen; however, the cadence and photometric noise could hide a weak shock signal. We simulate shocked light curves using SN Ia templates and a simple, Gaussian shock model to emulate the noise properties of the SDSS-II sample and estimate the detectability of the shock interaction signal as a function of shock amplitude, shock width, and shock fraction. We find no direct evidence for shock interaction in the rest-frame $B$-band, but place an upper limit on the shock amplitude at 9% of supernova peak flux ($M_B > -16.6$ mag). If the single degenerate channel dominates type~Ia progenitors, this result constrains the companion stars to be less than about 6 $M_{\odot}$ on the main sequence, and strongly disfavors red giant companions.