title: On the Impact and Usefulness of  Intrinsic Alignments of Galaxies  in a Composite Model on  Weak Lensing in Tomographic Surveys
creator: Tugendhat, Tim Manfred
subject: ddc-520
subject: 520 Astronomy and allied sciences
subject: ddc-530
subject: 530 Physics
description: Future weak lensing surveys will be too precise for their own good: due to their impressive statistical precision, their systematics must be treated with extreme care.  In particular, intrinsic alignments (IA) of galaxies, which cause galaxy ellipticities to be correlated, are indistinguishable from gravitational lensing. I present two established models for IAs and will link them to the physical properties of two galaxy morphologies, namely spiral and elliptical galaxies.  Their amplitudes relative to the lensing spectrum is determined and a realistic mix of galaxies and thus utilised to predict the impact of IAs on a Euclid-like tomographic survey and its inferences on a cosmological parameter set. It will be shown that IAs will give rise to significant systematic errors (biases) in future surveys. Furthermore, I present a method for suppressing the IA signal by using colour information and separating the survey into subsamples of blue and red galaxies. This method can also be used to suppress the lensing signal instead, enabling the treatment of just IAs. Finally, I will show a possible way of constrain deviations from General Relativity (Gravitational Slip) by using the model for elliptical galaxies and leveraging its signal against the one from a known weak lensing signal.
date: 2018
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/24514/1/tim-tugendhat-thesis.pdf
identifier: DOI:10.11588/heidok.00024514
identifier: urn:nbn:de:bsz:16-heidok-245143
identifier:   Tugendhat, Tim Manfred  (2018) On the Impact and Usefulness of Intrinsic Alignments of Galaxies in a Composite Model on Weak Lensing in Tomographic Surveys.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/24514/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng