Type II-Plateau supernova radiation: dependences on progenitor and explosion properties

Abstract

We explore the properties of Type II-Plateau (II-P) supernovae (SNe) together\nwith their red-supergiant (RSG) star progenitors. Using MESA STAR, we modulate\nthe parameters (e.g., mixing length, overshoot, rotation, metallicity) that\ncontrol the evolution of a 15Msun main-sequence star to produce a variety of\nphysical pre-SN models and SN II-P ejecta. We extend previous modeling of SN\nII-P radiation to include photospheric and nebular phases, as well as\nmulti-band light curves and spectra. Our treatment does not assume local\nthermodynamic equilibrium, is time dependent, treats explicitly the effects of\nline blanketing, and incorporates non-thermal processes. We find that the color\nproperties of SNe II-P require large model atoms for FeI and FeII, much larger\nthan adopted in Dessart & Hillier (2011). The color properties also imply RSG\nprogenitors of limited extent (~500Rsun) --- larger progenitor stars produce a\nSN II-P radiation that remains too blue for too long. This finding calls for a\nreduction of RSG radii, perhaps through a strengthening of convective energy\ntransport in RSG envelopes. Increased overshoot and rotation reduce the ratio\nof ejecta to helium-core mass, similarly to an increase in main-sequence mass,\nand thus complicate the inference ofprogenitor masses. In contrast to the great\nsensitivity on progenitor radius, SN II-P color evolution appears insensitive\nto variations in explosion energy. Finally, we document the numerous SN II-P\nsignatures that vary with progenitor metallicity, revealing their potential for\nmetallicity determinations in the nearby and distant Universe.\n