Title: Cosmological constraints from weak lensing, SNIa and CMB. - Sampling the posterior

Time: Nov. 27th, 10:30AM

Location: middle conf. room, 3rd floor

Abstract:

In the first part of my talk I will present recent results on joint cosmological parameter constraints. We combine CFHTLS weak lensing,SNLS supernovae Ia and WMAP5 data to test a dark energy model with constant equation of state w. Particular care is put on the influence of systematics and their correlations with cosmological parameters.Including systematics from weak lensing and SNIa we find no deviation from a LCDM model, with -0.1 < 1+w < 0.06 at 68% confidence.The second part of my talk covers a new method of sampling the parameter space. We developped and implemented an iterative scheme for importance sampling, called population Monte Carlo (PMC). It is efficient and parallelizable, and overcomes some problems inherent to Markov Chain Monte Carlo (MCMC) methors. I will present the basics of the PMC algorithm and show its application to cosmology.