Type Ia Supernova Progenitor Properties and their Host Galaxies

Abstract

We present an eigenfunction method to analyze 161 visual light curves (LCs) of Type Ia supernovae (SNe Ia) obtained by the Carnegie Supernova Project to characterize their diversity and host-galaxy correlations. The eigenfunctions are based on the delayed-detonation (DD) scenario using three parameters: the LC stretch s determined by the amount of deflagration burning governing the ^56 Ni production, the main-sequence mass M _MS of the progenitor white dwarf controlling the explosion energy, and its central density ρ _c shifting the ^56 Ni distribution. Our analysis tool (Supernova Parameter Analysis Tool) extracts the parameters from observations and projects them into physical space using their allowed ranges ( M _MS ≤ 8 M _⊙ , ρ _c ≤ 7–8 × 10 ^9 g cm ^−3 ). The residuals between fits and individual LC points are ≈1%–3% for ≈92% of objects. We find two distinct M _MS groups corresponding to a fast (≈4–65 Myr) and a slow(≈200–500 Myr) stellar evolution. Most underluminous SNe Ia have hosts with low star formation but high M _MS , suggesting slow evolution times of the progenitor system. 91T-like SNe show very similar LCs and high M _MS and are correlated to star formation regions, making them potentially important tracers of star formation in the early Universe out to z ≈ 4–11. Some ∼6% outliers with nonphysical parameters using DD scenarios can be attributed to superluminous SNe Ia and subluminous SNe Ia with hosts of active star formation. For deciphering the SNe Ia diversity and high-precision SNe Ia cosmology, the importance is shown for LCs covering out to ≈60 days past maximum. Finally, our method and results are discussed within the framework of multiple explosion scenarios, and in light of upcoming surveys.

Keywords

• Type Ia supernovae