Scientific Seminars

Cosmological tests of General Relativity with tomographic surveys

A. Silvestri
MIT

2010-12-09    11:00    Merate - POE

Future cosmological surveys, combining galaxy counts and weak lensing measurements, will map the evolution of matter perturbations and gravitational potentials from the matter dominated epoch until today. In addition to tightening the constraints on allowed expansion histories, the combination of these measurements will test the relationships between matter overdensities, local curvature, and the Newtonian potential. These relationships can be modified in alternative theories of gravity and by exotic forms of Dark Energy. I will discuss theoretical issues involved in finding an optimal parametrization to study deviations from GR on cosmological scales, high-light the importance of allowing for scale-dependent features and introduce the application of the Principal Component Analysis (PCA) to the evolution of cosmological perturbations. This technique allows us to asses the potential of upcoming and future tomographic surveys, such as EUCLID, DES and LSST, with the aid of CMB and supernovae data, to detect departures from the growth of perturbations expected within General Relativity with a cosmological constant. It can also be applied to current data; to this extent, I will show constraints on GR obtained applying the PCA technique to existing cosmological data, allowing for time- and scale-dependent deviations from the standard LCDM model.