The Cosmic Microwave Background (CMB) is our most powerful probe of cosmological parameters, and in the realm of CMB measurements, the Planck satellite currently offers the tightest constraints on temperature anisotropies over the majority of angular scales relevant for the CMB. Ealier this year, the first CMB results from Planck were released, touching many aspects of cosmology. In this talk, I will focus mainly on one aspect: what have we learned about neutrinos from Planck? In particular, I will give an explanation aimed at non-CMB experts for how measurements of the Slik damping in the CMB lead to constraints on N_eff, the number of relativistic degrees of freedom, and how measurements of gravitational lensing of the CMB lead to constraints on \Sigma m_\nu, the sum of the masses of the neutrinos. I will also show how adding other low-redshift probes such as Baryon Acoustic Oscillation (BAO) measurements and local measurements of the Hubble constant (H_0) lead to improved constraints on these parameters. Doing so will offer a chance to explain how Planck results fit in with other recent CMB measurements such as from the WMAP satellite, the South Pole Telescope, and the Atacama Cosmology Telescope, in particular commenting on the source of the "low" Planck H_0 result that has attracted some interest and is related to the neutrino mass constraint. Finally, I will take a quick look at what to expect from the release of the full Planck data, to come in summer 2014.
address: Department of Astronomy, MC-221, 1002 W. Green Street, Urbana, IL 61801 phone: (217) 333-3090 • fax: (217) 244-7638 • email:firstname.lastname@example.org