Planck 2015 results. XIII. Cosmological parameters

P.A.R Ade, N. Aghanim, M. Arnaud, M. Ashdown, J. Aumont, C. Baccigalupi, A.J. Banday, R.B. Barreiro, J.G. Bartlett, N. Bartolo, E. Battaner, Per Rex Christensen, Anne Mette Frejsel, Pavel Nasselski, Igor Dmitrievich Novikov, Hans Ulrik Nørgaard-Nielsen