Séminaire de Physique ThéoriqueSupernova cosmology and the 3-year SNLS (SuperNova Legacy Survey) results
Thursday 06 May 2010 14:00 - Tours - Salle 1180 (Bât E2)
In science, the most important revolutions are often initiated by small disagreements. One significant result of the last decade is the discovery in 1998 of the accelerated expansion of the universe. A small deviation from the expected luminosity of distant Type Ia supernovae (SNe Ia) led physicists to conclude their ignorance with respect to the constitution of ~ 70% of the universe. The universe would be filled with a new substance of still undetermined nature, which is responsible for the acceleration of the universe, now referred to as Dark Energy. SNe Ia can be considered as standard candles having uniform light curves with a small dispersion among their peak brightness, and as a consequence, they can be used to measure distances accurately. By studying the distance-redshift relation of a large number of supernovae, precise constraints on cosmology have been obtained. Since 1998, new supernovae surveys have been initiated giving rise to a rapidly increasing SN Ia dataset. One of the important surveys is the SuperNova Legacy Survey (SNLS). I will in this talk present the basics of SN Ia physics and their use in cosmology together with the latest cosmological results from the SNLS and some of the difficulties today’s SN surveys are facing. I will also give a brief summary of my thesis work, gravitational lensing of the SNLS SNe. I will show that estimating the magnification of type Ia SNe can be used to measure the dark matter clustering of foreground galaxies.