Attention ! Jour et heure inhabituels !
The last dozen years has seen great progress in our use of Type Ia supernovae (SNe) to measure cosmological parameters : from the discovery of the accelerating Universe in 1998 using a few dozen SNe, to the most recent constraints on the nature of dark energy using over 500 SNe. Einstein's cosmological constant, in which the dark energy equation of state parameter is exactly minus one, is consistent with current data, but so are several alternative models, in which the equation of state is not minus one and is varying with time. Differentiating between these two possibilities is now the most important goal in SN cosmology.
In this talk, I will give an overview of how we use SNe to measure cosmological parameters, present some recent results and discuss new work that aims to increase the number of SNe and to reduce some of the largest sources of systematic uncertainty.