Testing the Next Generation of Cosmological Surveys

We demonstrate the joint correlations between the observed density contrast and the magnification of galaxies. Different multipoles of these are then extracted to provide new observables which give independent information about the growth of structure, the velocity field of galaxies and so on. This are calculated in general relativity, as a means of more accurately using galaxy surveys to calculate the parameters of the concordance model. Predictions are then made for surveys such as Euclid and the SKA. Once the variability of each new observable is determined, they are generalised to generic modified gravity theories. Many theories of gravity can be encompassed within a broader context whereby deviations from general relativity can be parameterised by free functions.