Exploring the efficacy and limitations of shock-cooling models: new analysis of Type II supernovae observed by the Kepler mission

Modern transient surveys have begun discovering and following supernovae (SNe) shortly after first light---providing systematic measurements of the rise of Type II SNe. We explore how analytic models of early shock-cooling emission from core-collapse SNe can constrain the progenitor's radius, explosion velocity, and local host extinction. We simulate synthetic photometry in several realistic observing scenarios and, assuming the models describe the typical explosions well, find that ultraviolet observations can constrain the progenitor's radius to a statistical uncertainty of $\pm10-15\%$, with a systematic uncertainty of $\pm 20\%$. With these observations the local host extinction ($A_V$) can be constrained to a factor of two and the shock velocity to $\pm 5\%$ with a systematic uncertainty of $\pm 10\%$. We also re-analyze the SN light curves presented in Garnavich et al. (2016) and find that KSN 2011a can be fit by a blue supergiant model with a progenitor radius of $R_s < 7.7 + 8.8 {\rm (stat)} + 1.9 {\rm (sys)}R_\odot$, while KSN 2011d can be fit with a red supergiant model with a progenitor radius of $R_s = 111_{-21 {\rm (stat)}}^{+89 {\rm (stat)}} \phantom{}_{-1{\rm (sys)}}^{+49 {\rm (sys)}}$. Our results do not agree with those of Garnavich et al. (2016). Moreover, we re-evaluate their claims and find that there is no statistically significant evidence for a shock breakout flare in the light curve of KSN 2011d.