Improved cosmological constraints from the joint analysis of the SDSS and SNLS Type Ia supernova samples

Julien Guy


I will present recent progress in the measurement of cosmological parameters with type Ia supernovae which result mainly from a significant improvement in the photometric calibration of the SNLS and SDSS surveys.

The high supernova statistics gathered recently, combined with a sub-percent accuracy in the relative flux calibration, allows us to map the variations of the luminosity distance as a function of z with a relative precision of about 3% in logarithmic redshift bins delta_z/z = 0.5 between to z = 0.02 and z = 0.7. This approach is, today, the most sensitive probe of Dark Energy. Combining with the recent CMB measurement from Planck, we obtain an accuracy better than 6% on the equation of state parameter w.