Name: Fabio Finelli
 Institution: Institute of Spatial Astrophysics and Cosmic Phisics Bologna
 Title: CMB Constraints on a Stochastic Background of Primordial Magnetic Fields
 Key Words: cosmology, CMB anisotropies, primordial magnetic fields
 Abstract: We constrain a stochastic background of primordial magnetic field by the most recent compilation of CMB anisotropies. By  parametrizing such stochastic background by a power-law spectrum with index n and by its Gaussian smoothed amplitude B on a comoving length of 1 Mpc, we obtain B < 5.0 nG and n<-0.12 at 
95 % CL. We forecast Planck capabilities in constraining B and n. We end in discussing the signatures in the bispectrum of such stochastic background.