Uncertainties on LCDM through inhomogeneities
Wiegand, Alexander (Universitaet Bielefeld)

Despite its global homogeneity and isotropy, the matter distribution in the late universe is manifestly inhomogeneous. Cosmological backreaction suggests a link between the structure formation, that lead to this inhomogeneity, and the expansion history of the Universe. In order to quantitatively examine this connection there have been many studies using cosmological perturbation theory. While the global acceleration turns out to be small, we expect sizable effects on the evolution of our local volume and its cosmic parameters. This talk examines in which case there is a global effect and when there are only domain dependent contributions. For these latter it is shown on which scales they become important and how they, therefore, restrict our ability to measure the average local cosmic parameters. To this end the corresponding uncertainties for recent galaxy surveys are presented. As especially the curvature parameter is affected, it will be analyzed whether the resulting degeneracy with the cosmological constant will influence our ability to measure its equation of state.