The speaker will be Avishay Gal-Yam
Place: Holcblat Hall
Time: Wednesday, 27/Nov/2002, 14:00
Title: Supernovae in Galaxy Clusters
The rate of supernovae (SNe) in galaxy clusters is central to understanding a host of problems, from metal enrichment and energetics of the intra-cluster medium (ICM) to the nature of the progenitors of SNe-Ia. However, very little has been known about the cluster SN rate, especially at high redshifts where such measurements would be most revealing. Using the Wise Observatory 1m telescope, we have discovered 16 SNe in a sample of nearby (0.06 < z < 0.2) galaxy clusters, which we use to calculate the cluster SN-Ia rate. This search has also revealed the first examples of intergalactic SNe, unbound to any one galaxy in the cluster. The ratio of intergalactic events to ``normal'' SNe in cluster galaxies measures the fraction of intergalactic stars. Extending this work to higher z, we have searched for SNe in deep HST cluster images, discovering six events. With these, we have measured the cluster SN-Ia rate out to z=1, and placed constraints on the origin of ICM iron. These data also probe, for the first time, the properties of the high -z field population of SNe of all types. I conclude with some future prospects.