Intrinsic ellipticity correlations between galaxies

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The next generation of weak lensing surveys will aim to constrain the cosmological parameters to an accuracy of a few percent, in particular they will measure the dark energy equation of state parameter and its time evolution to very high accuracy. In order to reach this accuracy, one needs a very good control of systematics, most importantly of the photometric redshift estimation of the lensed galaxies, in particular for tomographic measurements, and of intrinsic ellipticity correlations, which mimick the weak lensing signal. These intrinsic alignments are induced by the correlations between angular momenta of neighbouring galaxies and have been shown to affect the estimation of parameters significantly. The central goal of this project is to improve the understanding of ellipticity alignments, which are related to the tidal field of the large-scale structure by angular momentum models, by deriving higher-order correlation functions. Furthermore, we aim to investigate the feasibility of density field reconstructions using intrinsic ellipticity correlations, which were shown to dominate at low redshift over the weak lensing induced ones.