Cosmological Tests of General Relativity with Future Tomographic Surveys

Zhao, Gong-Bo
Pogosian, Levon
Silvestri, Alessandra
Zylberberg, Joel
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Future weak lensing surveys will map the evolution of matter perturbations and gravitational potentials, yielding a new test of general relativity on cosmic scales. They will probe the relations between matter overdensities, local curvature, and the Newtonian potential. These relations can be modified in alternative gravity theories or by the effects of massive neutrinos or exotic dark energy fluids. We introduce two functions of time and scale which account for any such modifications in the linear regime. We use a principal component analysis to find the eigenmodes of these functions that cosmological data will constrain. The number of constrained modes gives a model-independent forecast of how many parameters describing deviations from general relativity could be constrained, along with $w(z)$. The modes' scale and time dependence tell us which theoretical models will be better tested.
Comment: New title, added discussion and references, matches the version accepted to Phys.Rev.Lett
Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology