Preliminary Estimates of Core-collapse Supernova Rates from the Berkeley Automated Supernova Search
Over the last few years, the Berkeley Automated Supernova Search has discovered 19 supernova. We present here preliminary measurements of supernova rates from a subset of these supernovae, which were found from a sample of well-monitored galaxies. Two effects are apparent: a surprising number of the supernovae are Type Ic supernovae, and most (17 out of 19) of the supernovae are in late spiral galaxies. Less luminous supernovae may still be escaping our attention. If the Milky Way galaxy is a late spiral, the core-collapse supernova rate (i.e., for supernovae of types II, Ib, and Ic) should be at least one supernova every 44 {plus minus} 9 years (assuming H = 75 km/sec/Mpc). A crude estimate of the core collapse supernova rate in Sc and Sbc galaxies within 5 Mpc would be one supernova every 7 years. These rates have important implications for the design of supernova neutrino, gamma-ray, and gravity-wave detectors. Plans have been developed to extend our search to a better site with more sensitivity to understand the true core-collapse supernova rate in nearby galaxies. 13 refs.
Two effects are apparent: a surprising number of the supernovae are Type Ic supernovae, and most (17 out of 19) of the supernovae are in late spiral galaxies. Less luminous supernovae may still be escaping our attention.