A Comparative Study of the Absolute Magnitude Distributions of Supernovae

The Asiago Supernova Catalog is used to carry out a comparative study ofsupernova absolute-magnitude distributions. An overview of the absolutemagnitudes of the supernovae in the current observational sample is presented,and the evidence for subluminous and overluminous events is examined. Thefraction of supernovae that are underluminous (M_B > -15) appears to be higher(perhaps much higher) than one fifth but it remains very uncertain. Thefraction that are overluminous (M_B < -20) is lower (probably much lower) than0.01. The absolute-magnitude distributions for each supernova type, restrictedto events within 1 Gpc, are compared. Although these distributions are affectedby observational bias in favor of the more luminous events, they are useful forcomparative studies. We find mean absolute blue magnitudes (for H_0=60) of-19.46 for normal Type Ia supernovae (SNe Ia), -18.04 for SNe Ibc, -17.61 and-20.26 for normal and bright SNe Ibc considered separately, -18.03 for SNeII-L, -17.56 and -19.27 for normal and bright SNe II-L considered separately,-17.00 for SNe II-P, and -19.15 for SNe IIn.Comment: 27 pages, accepted for publication by the Astronomical Journal (Feb. 2002