Planck constraints on the effective neutrino number and the CMB power spectrum lensing amplitude

Abstract

We present new constraints on the relativistic neutrino effective number N_eff and on the cosmic microwave background power spectrum lensing amplitude A_L from the recent Planck 2013 data release. Including observations of the cosmic microwave background large angular scale polarization from the Wilkinson microwave anisotropy probe (WMAP) satellite, we obtain the bounds N_eff=3.71±0.40 and A_L=1.25±0.13 at 68% C.L. We discuss the agreement of these results with the previous constraints obtained from the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT). Considering the constraints on the cosmological parameters, we found a very good agreement with the previous WMAP+SPT analysis but a tension with the WMAP+ACT results, with the only exception of the lensing amplitude.