Intrinsic ellipticity correlations between galaxies
Final Report Abstract
Ellipticity correlations between galaxies which are caused by their coupled angular momenta are a fascinating research topic. On the theoretical side they touch our understanding of cosmic structure formation and the tidal forces in the cosmic large-scale structure, which induce angular momentum into protogalaxies, and on the practical side we require an understanding of these ellipticity correlations for our interpretation of the weak cosmic lensing effect, in particular for the estimation of cosmological parameters. Purpose of this proposal was to address the following question: How well do ellipticities trace the tidal shear field and therefore the density field? If the relation is sufficiently tight, it is possible to reconstruct the local cosmic density field using the observed ellipticity field as a tracer. There is theoretical evidence in the from of a spin-density correlation that this should be possible. In a secondary project, we quantified the statistics of intrinsic alignments and their influence on the estimation of cosmological parameters from weak lensing data.
