Weak lensing effects of dark matter filaments between galaxy pairs

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Weak lensing effects of dark matter filaments between galaxy pairs

Type: Master thesis
Title: Weak lensing effects of dark matter filaments between galaxy pairs
Author: Vink, Frederik Teunis
Issue Date: 2018-07-31
Keywords: Dark matter
weak lensing
galaxy pairs
Abstract: We will show the weak lensing effects from filaments connecting galaxy pairs for two separate galaxy subsets. The lensing galaxies are selected from the Galaxy And Mass Assembly (GAMA) survey, where we use version 7 of the GAMA galaxy group catalogue in our galaxy selection. We select the background galaxies from the ’KiDS-450’ weak lensing data set. Two galaxies are considered to form a pair when they are within an angular separation of 6h^-1 Mpc and 10h^-1 Mpc and are within a line of sight separation of 10h^-1 Mpc. In addition, we select galaxies with an angular separation between 6h^-1 Mpc and 10h^-1 Mpc, with a line of sight separation between 100h^-1 Mpc and 120h^-1 Mpc, to be ’unphysical pairs’. They appear to be galaxy pairs projected on the sky but are physically to far separated to form a pair. The subtraction of the signal of the unphysical pairs from the physical pairs will then result in the isolation of the filament. We use two subsets of galaxies in our pair selection; galaxies isolated in space, and the central galaxies of galaxy groups with at least 4 group members and consider the lensing effects of both subsets. Using 25 000 and 8 279 galaxy pairs from the isolated galaxy pairs subset and group central galaxy pair subset respectively, we will show the detection of filaments with a significance of 2.3\sigma and 2.9\sigma for these subsets.
Description: Version of 4th of October 2017. As instructed, the student ID was removed on the 28th of May 2018, which explains the date of creation of the thesis.
Supervisor: Kuijken, Koen
Faculty: Faculty of Science
Department: Physics (Master)
Specialisation: Cosmology
ECTS Credits: 4
Handle: http://hdl.handle.net/1887/62121

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