%0 Generic
%A Guarnizo Trilleras, Alejandro
%D 2016
%F heidok:20369
%R 10.11588/heidok.00020369
%T A Model-Independent Approach to Dark Energy Cosmologies: Current and Future Constraints
%U https://archiv.ub.uni-heidelberg.de/volltextserver/20369/
%X The effective anisotropic stress eta = − Phi/Psi	 is a key variable in the characterisation of the physical  origin of the dark energy. It is however important to use a fully model-independent approach when  measuring eta to avoid introducing a theoretical bias into the results. We forecast the precision  with which future large surveys can determine eta in a way that only relies on directly observable  quantities, using the joint combination of Galaxy Clustering, Weak Lensing and Supernovae probes.  Among the results, we find that a future large scale survey can constrain eta to within 10% if k-independent,  and to within 60% if it is restricted to follow the Horndeski model. In order to  find current constraints on eta data for the growth rate f sigma_8 coming from Redshift Space Distortion  measurements, observations of the Hubble expansion H(z), and a constraint for the quantity  P2 defined as the expectation value of the ratio between galaxy-galaxy and galaxy-velocity cross  correlations, have been used. We find a value at z = 0.32 of eta = 0.646 +/- 0.678, in agreement with  the predicted value for the LCDM model. Finally, we produce a cosmological exclusion plot for  modified gravity in analogy with the exclusion plots produced in laboratory experiments.