Vorschau

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Abstract

The subject of this thesis are different aspects of cosmology as a probe of the underlying gravitational theory with future surveys. In the first part of this work we discuss the parameter dependence of covariance matrices of the power spectrum estimator of the large-scale structure. Its variation across parameter space is calculated analytically by constructing a suitable basis and is then compared with numerical simulations. The method presented is applicable to any matrix-valued function which is everywhere positive-definite. The second part investigates the influence of tidal gravitational fields on the formation of dark matter halos at peaks in the density field of the large-scale structure. We extend the spherical collapse model to incorporate the influence of shear and rotation by treating them as inhomogeneities in the non-linear evolution equation. We investigate the statistics of the tidal field and how it is inherited to the statistics of the critical over-density δc. It is shown that the collapse in a tidal field will always proceed faster than the collapse in a homogeneous background. The last part investigates the combination of observations of weak gravitational lensing, galaxy clustering and the cosmic microwave background and the cross-correlations between the probes to investigate scalar-tensor theories of gravity. We carry out a Fisher analysis as well as a Monte-Carlo-Markov-chain to estimate the expected statistical errors. The analysis shows that gravitational theories can be constrained very well with future surveys.