Constraining Modified Gravity and Growth with Weak Lensing

by Prof. Jochen Weller (Universita' di Monaco)

Wednesday 3 Jun 2009, 16:00 → 17:00 Europe/Rome

Aula Corbino (Dipartimento di Fisica - Ed. E.Fermi)

The idea that we live in a Universe undergoing a period of acceleration is a strongly held notion in cosmology. As this can, potentially, be explained with a modification to General Relativity we look at current cosmological data with the purpose of testing aspects of gravity. Firstly we constrain a phenomenological model (mDGP) motivated by a possible extra dimension. In addition, we utilise Weak Lensing data (CFHTLS-wide) in combination with Baryon Acoustic Oscillations (BAOs) and Supernovae data. We show that current weak lensing data is not yet capable of constraining either model in isolation. Ho! wever we demonstrate that this probe is highly beneficial, for in combination with BAOs and Supernovae since without the lensing data no constraint is possible. Both analyses disfavour the flat DGP braneworld model. We highlight these are insensitive to potential systematics in the lensing data. For the growth signatre we show that, in combination, these probes do not yet have sufficient constraining power. Finally, we look beyond these present capabilities and demonstrate that Euclid, a future weak lensing survey, will deeply probe the nature of gravity.