The detection of z 2 type IIn supernovae in the CFHTLS Deep fields

Type IIn supernovae (SNe IIn) result from the deaths of the most massive stars. SNe IIn are among the brightest supernovae events ever recorded and are the brightest supernovae type in the rest-frame UV. These aspects make them ideal targets for high redshift searches. I will describe our method of detecting z 2 SNe IIn events in the CFHTLS Deep survey and present compelling photometric candidates and Keck spectroscopic host galaxy redshifts. I will discuss the implications of the results on the universal SNe IIn density, high-redshift Type II supernova rate, and galaxy initial mass function. In addition to their photometric detectability, SNe IIn spectra exhibit extremely bright, long-lived emission lines that are a result of the interaction between the SN ejecta and cool circumstellar material released in pre-explosion outbursts. The lines remain bright for years and are above the spectroscopic thresholds of current 8m-class telescope out to z 3. The detection and evolution of SNe IIn emission lines can be used to confirm high redshift events and measure their energies. I will discuss our future program to spectroscopically confirm the emission of detected z 2 SNe IIn and the potential of future projects such as LSST and TMT to detect events to z 6