Synthetic spectra of supernovae models

Dedicated spectroscopic facilities can follow up these events shortly after detection. Here we investigate the properties of these explosions at early times.We use the radiative transfer code CMFGEN to build an extensive library of spectra simulating the interaction of supernovae and their progenitor's winds/circumstellar medium (CSM).We consider a range of progenitor mass-loss rates (dM/dt=5x10^-4^ to 10^-2^ M_{sun}/yr), abundances (solar, CNO-processed, and He-rich), and SN luminosities (L=1.9x10^8^ to 2.5x10^10^L_{sun}_).

The models simulate events ~=1-day after explosion, and we assume a fixed location of the shock front as R_in_=8.6x10^13^cm. We show that the large range of massive star properties at the pre-SN stage causes a diversity of early-time interacting SN and impostors. We identify three main classes of early-time spectra consisting of relatively high-ionisation (e.g. HeII and OVI), medium-ionisation (e.g. CIII and NIII), and low-ionisation lines (e.g. HeI and FeII/III).