On the Intrinsic Diversity of Type IIPlateau Supernovae
Abstract
Hydrogenrich Type IIPlateau supernovae (SNe) exhibit correlations between the plateau luminosity {L}_{{pl}}, the nickel mass {M}_{{Ni}}, the explosion energy {E}_{{exp}}, and the ejecta mass {M}_{{ej}}. Using our global, selfconsistent, multiband model of nearby wellobserved 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 {L}_{{pl}}, {E}_{{exp}} and {M}_{{Ni}}, where the uncertainties due to the distance and the extinction dominate. For fixed {E}_{{exp}}, the spread in {M}_{{Ni}} is about 0.25 dex, which we attribute to the differences in the progenitor internal structure. We argue that the effects of incomplete γray trapping are not important in our sample. Similarly, the physics of the Type IIPlateau SN light curves leads to inherently degenerate estimates of {E}_{{exp}} and {M}_{{ej}}, 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 IIPlateau SN explosions are not described by a single physical parameter or a simple onedimensional 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.
 Publication:

The Astrophysical Journal
 Pub Date:
 June 2015
 DOI:
 10.1088/0004637X/806/2/225
 arXiv:
 arXiv:1501.06573
 Bibcode:
 2015ApJ...806..225P
 Keywords:

 methods: statistical;
 stars: distances;
 supernovae: general;
 Astrophysics  Solar and Stellar Astrophysics;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 8 pages, 5 figures, accepted to ApJ