Supervisors
We offer a number of possible student projects within our lensing group. The projects would be co-supervised by Prof. Dr. Peter Schneider and myself. If you are interested in a project, please contact psimon[at]astro.uni-bonn.de or visit us at the AIfA.
We have
- Bachelor thesis projects;
- Master thesis projects;
- Doctoral thesis projects.
Stroked out projects are no longer available.
A list of former projects can be found here.
Bachelor projects
-
Interpretation of galaxy-galaxy-galaxy lensing with a simplified halo model (Bachelor) -
Measurement of excess mass around galaxy pairs in CFHTLenS (Bachelor) -
Improvement of the signal-to-noise ratio of excess mass measurements around galaxy pairs with redshift information (Bachelor) -
Halo shapes from galaxy-galaxy-galaxy lensing (Bachelor)
- Effect of matter-galaxy misalignment inside elliptical dark matter
haloes on excess mass maps (Bachelor)
Master projects
-
CFHTLenS: Scale-dependent galaxy bias (Master)
-
Refined search for mass peaks and galaxy clusters with 3-D gravitational lensing (Master)
As one application of the weak-gravitational lensing effect, we employ maps of the lensing aperture mass to search for massive concentrations in the projected matter density field. Significant peaks in maps of the aperture mass are typically associated with galaxy clusters but, on the other hand, may also be mere projections of several smaller mass concentrations along the line of sight or systematic errors. The aim of this project is to exploit distance information of the source galaxies in the lensing analysis to combine maps for source samples binned in distance in order to constrain the distance of mass concentrations and to distinguish the projection of several small mass concentrations from one single large concentration. This can be achieved, in principle, by applying a (regularised) Wiener filter to measurements of the aperture mass with different source-distance bins in the direction of peaks, or by applying fits of sparse mass models to these data. In addition, the lensing signal could be combined with a (noisy) aperture statistics of the foreground galaxy-density for a combined search for galaxy clusters. A fully worked out methodology shall then be applied to existing CFHTLenS data to search for mass peaks or galaxy clusters, and to compare their positions on the sky, mass and distance estimates, to known galaxy clusters.
- KiDS&GAMA: Biasing of GAMA galaxies from linear to non-linear scales as
function of galaxy type (Master)
Galaxies are biased tracers of the matter-density field that constitutes the cosmic web. One way to quantify galaxy biasing statistically is by functions that express both the fluctuations in the galaxy density field relative to that in the matter field and the correlation between both. The detailed dependence of the galaxy bias on galaxy type, redshift, and spatial scale is a test for galaxy models -- but is also of relevance for methods that rely on a scale-invariant galaxy bias or a high correlation between the galaxy and matter density. In our recent paper (SH17), we show that these biasing functions can be measured with gravitational lensing to about 5 per cent accuracy. The goal of this project is to apply the SH17 methodology to GAMA galaxies and the lensing signal in KiDS to systematically compile the first reference library of biasing functions for galaxies at redshift z<0.4 that are binned in stellar mass, luminosity, and galaxy type (180 square degree usable survey area). A computer code for the data correlation and lensing analysis, lens and shear catalogues, and bias predictions from the SAM are available.
- Constraining intrinsic source alignment in cosmic shear surveys with determinstic galaxy bias on large scales (Master)
Doctoral projects
-
Consistency of galaxy-galaxy-galaxy lensing predictions by a halo model with predictions of second-order statistics (Doctoral) -
CFHTLenS: Confrontation of observed galaxy-galaxy(-galaxy) lensing with predictions by semi-analytical galaxy models (Doctoral) -
KiDS&GAMA: The excess mass around mixed-type galaxy pairs in GAMA data (Doctoral)
Past projects
This is a list of student projects I have co-supervised in the past. The student's names are only given as initials for privacy reasons. If you would like to contact one of the students to talk about their experience in our group, please let me know.
| Year | Project | Type | Investigator |
|---|---|---|---|
| 2023 | Calculating excess mass around KiDS galaxy pairs on large scales with galaxy-galaxy-galaxy lensing | internship | ESR |
| 2021 | Testing models of galaxy formation and evolution with galaxy-galaxy-galaxy lensing | doctoral | LML |
| 2020 | Halo shapes from galaxy-galaxy-galaxy lensing | bachelor | WW |
| 2019 | Can the halo model describe 2nd- and 3rd-order correlation functions of gravitational lensing consistently? | doctoral | SM |
| 2017 | Improving the significance in maps of the excess mass for GAMA lens pairs and KiDS shear data | bachelor | PJS |
| 2017 | Messung und Interpretation einer Excess-Mass-Map im Galaxy-Galaxy-Galaxy-Lensing | bachelor | CB |
| 2016 | Comparing galaxy-galaxy(-galaxy) lensing in semi-analytic models and observations to study galaxy evolution | doctoral | HS |
| 2011 | Expectations for galaxy-galaxy-galaxy lensing from the halo model | diploma | DK |
| 2011 | Generalizing a cosmic shear analysis method, COSEBIs, to higher dimensions in parameter space and tomography | Master | MA |