Program: GS-2017A-Q-33

Despite their success as standardizable candles, relatively little is know about the exact progenitor(s) and explosion physics of type Ia supernovae -- a potential source of systematic uncertainty for future dark energy surveys, and a hole in our knowledge about stellar end-states. One promising route forwards is the combination of dense optical time series and near-infrared (NIR) spectroscopic data sets. Recent work has suggested that the NIR can discern unburned carbon from the progenitor white dwarf more cleanly than in the optical, and the PaBeta line roughly one month after maximum light can reveal the presence of a nondegenerate companion star. Both measures provide a direct constraint for SN Ia explosion models and their progenitor origins, but only a handful of appropriate NIR spectroscopic times series exist. We propose to continue our campaign to roughly double the sample of SN Ia with such data (leveraging our access to a worldwide network of 1m imaging telescopes and twin robotic optical spectrographs) in order to begin to tackle our understanding of NIR spectral diagnostics and how they vary from supernova to supernova.