Ultraviolet Emission from Shock Breakout in Type 11-P Supernovae

摘要

We present serendipitous GALEX detections of fast rising Ultraviolet emission fromtwo SNLS Type II plateau supernovae at z = 0.185 and 0.324. SNLS optical photometry and VLTspectroscopy 2 weeks after the GALEX detections link the onset of the UV emission to the timeof shock breakout. The UV light curves are in good agreement with our models for the immediateaftermath of shock breakout in a red supergiant (RSG) progenitor. We do not observe, and theGALEX observations likely missed, the bright (M_(FUV) ～ -20),short (< 1 hr) radiative precursorpredicted from stellar evolution models for the structure of the RSG envelope. Based on the observeddetection efficiency of our study we make predictions for the detection rage of shock breakouts fromType II SNe by the GALEX Time Domain Survey in parallel with Pan-STARRS 1.