Precision cosmology with type-Ia supernovae: past, present and future

par Dr Marc Betoule (LPNHE)

vendredi 13 déc. 2013, 14:30 → 16:30 Europe/Paris

9110 (Dpt. de Physique)

The industrial search for type-Ia supernovae that took place since the discovery of the accelerated expansion of the universe in the late nineties has been largely successful. With now about 1000 SNe-Ia on the Hubble diagram, recent cosmological analyses from type Ia supernovae face the limitation of measurement systematics and do not fully exploits the high statistics gathered in latest SN-Ia surveys. We present recent improvements on this topic: by reaching sub-percent accuracy in the relative flux calibration of the two main SNe surveys (SNLS and SDSS-II), we decreased the level of systematics, enabling to take full advantage of 3 years of the SNLS and SDSS-II data. We also performed detailed investigations of other important systematics associated to the SN-Ia light-curve model and survey selection biases. Our joint sample delivers the most sensitive constraints on Dark Energy to date, and is found compatible with a cosmological constant. In combination with the recent CMB measurement from Planck, we obtain a measurement of the constant equation of state parameter w in a flat universe with an accuracy better than 6%. We discuss improvement perspective for future surveys.