Constraints on modified gravity parameters from Planck and other data sets.

A possible solution for the cosmic acceleration problem may be a modification of general relativity at large scales. We consider a parametrization for modified gravity using similar to that used in the Planck 2015 analysis. We use the Boltzmann code CAMB for calculating the Cosmic Microwave Background (CMB) theoretical power spectrum and the code COSMOMC for cosmological parameter estimation in order to analyze this parametrization. We reproduce Planck 2015 results but question how the tension with General Relativity is being reduced using CMB Lensing. Finally, we make some remarks on the non-gaussianity of the modified gravity parameters and examine closely the tension observed.