Searching for Circumstellar Material in Type Ia Supernovae with Multi-Epoch High-Spectral-Resolution Observations


Abstract:
The question of the nature of type Ia supernova progenitors is a long standing one. One of the main properties that might help 
distinguish between the two mainly accepted proposed progenitor systems - the single and double degenerate systems - is the 
presence of circumstellar material in the vicinity of the exploding white dwarf, a relic of the progenitor system mass loss. This 
material should be ionized by the ultraviolet radiation of the explosion and later recombine, giving rise to time-variable absorption 
features. These features should be relatively narrow, due to the nature of the mass loss processes, hence, the need for 
high-spectral-resolution observations to detect them. The first detection of such features was reported for SN2006X. Since 
then, only a hand full of events have been published – two additional detections (SN2007le and PTF11kx) and three  
non-detections (SN2000cx, SN2007af, and SN2011fe). If we would like to deduce what fraction of type Ia supernovae have 
circumstellar material in their vicinity, hence, a possible single degenerate to double degenerate progenitors ratio, we must first 
enlarge this sample. I will report on the first steps of the renewed effort to build a large multi-epoch high-spectral-resolution 
sample and the effect of these new events on the current estimates of the single to double degenerate ratio.