Cosmology with the XXL survey

XXL is the largest contiguous X-ray survey undertaken by the XMM-Newton satellite (50deg2). It will permit to trace the large-scale structures through the distribution of ~500 galaxy clusters and 25000 active galactic nuclei. In this contribution, I will describe the predicted dark energy constraints based on the galaxy cluster number counts and correlation function. Then I will present and discuss the initial cosmological results of the survey based on the 100 brightest galaxy clusters published as part of the first data release. Finally, I will draw some perspective for the analysis of the entire data set.