A Comparative Study of the Absolute - Magnitude Distributions of Supernovae

The Asiago Supernova Catalog is used to carry out a comparative study of super-nova absolute-magnitude distributions. An overview of the absolute magnitudes of the supernovae in the current observational sample is presented, and the evidence for sub-luminous and overluminous events is examined. The fraction of supernovae that are underluminous (M B > −15) appears to be higher (perhaps much higher) than one fifth but it remains very uncertain. The fraction that are overluminous (M B < −20) is lower (probably much lower) than 0.01. The absolute-magnitude distributions for each supernova type, restricted to events within 1 Gpc, are compared. Although these distributions are affected by observational bias in favor of the more luminous events, they are useful for comparative studies. We find mean absolute blue magnitudes (for