Weidong Li
UC Berkeley
Abstract:
The Lick Observatory Supernova Search (LOSS), conducted with
a 30-in robotic telescope, is one of the most successful
nearby SN search engines in the past decade. Over 15,000 galaxies
have been monitored in the course of the search, yielding more than
1,000 SN discoveries. Our database of images and log files allow us
to construct a complete SN sample to derive the observed luminosity
functions (LFs) for the different SN types. These LFs, together with
other improvements in the analysis, allow us to derive the most
accurate rates for the nearby SNe to date. We find a surprising
correlation between the SN rates and the host galaxy sizes. I will
also discuss the two-component model for the SN Ia rates.
In the second part of my talk, I will discuss a method to improve
the accuracy of the distance measurements toward SNe Ia, by dividing
the SN Ia sample into two subclasses according to the expansion velocity
measurements from their spectra. We find that the so called "high-expansion velocity" events seem to have either a different
reddening law, or a different color/luminosity correlation, from
the "normal-expansion velocity" events. Implications of this method
will be discussed.