Abstract

First talk: New constraints on interacting dark energy and modified gravity models from Planck (Valentina)

In my seminar I present some recent results about two classes of exotic cosmological models: the interacting dark energy models and the modified gravity models of f{R} type. The new high-resolution cosmic microwave data from Planck are in good agreement with the previsions of the LCDM scenario but a complete physical interpretation of the dark components is still missing. Moreover some tensions exist between some parameter values as measured by Planck and as measured by other experiments or as calculated from the standard model. I show that the interacting dark energy and modified gravity models are compatible with the Planck measurements and that the parameter tensions can be alleviated or even solved in these non-standard scenarios.

Second talk: Constraints on Dark Radiation and Dark Energy (Najla)

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. We discuss the agreement of these results with the previous constraints obtained from the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT). We present also new constraints on the rest-frame sound speed, c_eff², and the viscosity parameter, c_vis², of the Cosmic Neutrino Background. Finally we combine measurements of Cosmic Microwave Background Anisotropies, Supernovae luminosity distances and Baryonic Acoustic Oscillations to derive constraints on the dark energy equation of state w in the redshift range [0,2], using a principal components approach.