| Abstract: | For the past decade, Type-Ia supernovae have been instrumental in measuring the cosmological parameters and in revealing the accelerating nature of the Universe's expansion. And yet, we still do not know what kind of stellar system is the progenitor of this type of supernova. In my talk, I will present three supernova surveys. Two are imaging-based surveys for high-redshift supernovae, the first conducted with the Subaru 8.2-m telescope in the Subaru Deep Field, and the second with the Hubble Space Telescope as part of the 3-year Multi-Cycle Treasury program CLASH. The third is a spectroscopic survey that searches for supernovae embedded in SDSS galaxy spectra. Using these supernovae, we measure the rates of Type-Ia supernovae out to redshift z=2. This type of measurement allows us to place constraints on the nature of the progenitor system. |
