Extinction and Radial Distribution of Supernova Properties in Their Parent Galaxies

We use a Monte Carlo technique and assumed spatial distributions of dust andsupernova (SN) progenitors in a simple model of a characteristic SN--producingdisk galaxy to explore the effects of extinction on the radial distributions ofSN properties in their parent galaxies. The model extinction distributions andprojected radial number distributions are presented for various SN types. Eventhough the model has no core-collapse SNe within three kpc of the center, aconsiderable fraction of the core-collapse SNe are projected into the innerregions of inclined parent galaxies owing to their small vertical scale height.The model predicts that because of extinction, SNe projected into the centralregions should on average appear dimmer and have a much larger magnitudescatter than those in the outer regions. In particular, the model predicts astrong deficit of bright core-collapse events inside a projected radius of afew kpc. Such a deficit is found to be present in the observations. It is anatural consequence of the characteristic spatial distributions of dust andcore-collapse SNe in galaxies, and it leads us to offer an alternative to theconventional interpretation of the Shaw effect.Comment: 14 pages, 4 figure