On the intrinsic diversity of Type II-plateau supernovae.
PEJCHA O. and PRIETO J.L.
Abstract (from CDS):
Hydrogen-rich Type II-Plateau supernovae (SNe) exhibit correlations between the plateau luminosity Lpl, the nickel mass MNi, the explosion energy Eexp, and the ejecta mass Mej. Using our global, self-consistent, multi-band model of nearby well-observed SNe, we find that the covariances of these quantities are strong and that the confidence ellipsoids are oriented in the direction of the correlations, which reduces their significance. By proper treatment of the covariance matrix of the model, we discover a significant intrinsic width to the correlations between Lpl, Eexp and MNi, where the uncertainties due to the distance and the extinction dominate. For fixed Eexp, the spread in MNi is about 0.25 dex, which we attribute to the differences in the progenitor internal structure. We argue that the effects of incomplete γ-ray trapping are not important in our sample. Similarly, the physics of the Type II-Plateau SN light curves leads to inherently degenerate estimates of Eexp and Mej, which makes their observed correlation weak. Ignoring the covariances of SN parameters or the intrinsic width of the correlations causes significant biases in the slopes of the fitted relations. Our results imply that Type II-Plateau SN explosions are not described by a single physical parameter or a simple one-dimensional trajectory through the parameter space, but instead reflect the diversity of the core and surface properties of their progenitors. We discuss the implications for the physics of the explosion mechanism and possible future observational constraints.
methods: statistical - stars: distances - supernovae: general