The Supernova Legacy Survey: Dark Energy and Type Ia Supernovae
Andy Howell, University of Toronto
The five year Supernova Legacy Survey (SNLS) has discovered more than 350 Type Ia supernovae (SNe Ia) in four years of operation with the goal of measuring the Dark Energy equation of state, w. In addition to producing the best published constraints on Dark Energy, we have made progress in understanding Type Ia supernovae as distance indicators and astrophysical phenomena. One surprise is the case of SNLS-03D3bb, a supernova whose extreme brightness and low expansion velocity imply that it is the explosion of a white dwarf that exceeded the theoretical maximum mass, the Chandrasekhar limit. This supernova is an extreme case of bright SNe Ia that are associated with star formation, whose rates are increasing with redshift. We show that the average properties of supernovae are evolving with redshift, and discuss the implications for current measurements of w and future measurements of time-variable w.