Bruinse, Thomas (2021) Cosmic Voids: Persistence and Hierarchy within the density and potential field. Bachelor's Thesis, Astronomy.
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Abstract
As cosmic voids are a very prominent component of the cosmic web, a great deal of attention goes towards discovering their structure and their effect on the other cosmic constituents. Because the gravitational force field is very weak inside these big near-empty regions with sizes of roughly 20 to 50 Mpc, they form unique laboratories to probe the effect of dark energy by looking at their their shape and evolution. Topological Data Analysis (TDA) and watershed transforms provide a great method to reveal their sizes and shapes, together with their rich hierarchical structure. Watershed Void Finder (WVF) can be used as a tool for the identification and segmentation of voids, by choosing the right threshold parameters. The topology of voids will be described by looking at their persistence, based on the concept of the Morse-Smale complex. Voids will then be found through the critical points in the density field. Their shapes can be approximated by fitting an ellipsoid. By transforming the density field to a gravitational field through Poisson’s equation, the same analysis can be done on the potential. Their features can be compared to give more insight into the dynamics of voids. A more thorough study of the gravitational potential field at various redshifts might then provide a better understanding of the Sachs-Wolfe effect and its connection to the temperature fluctuations in the Cosmic Microwave Background (CMB).
| Item Type: | Thesis (Bachelor's Thesis) |
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| Supervisor name: | Weijgaert, M.A.M. van de and Wilding, G. |
| Degree programme: | Astronomy |
| Thesis type: | Bachelor's Thesis |
| Language: | English |
| Date Deposited: | 19 Jul 2021 13:22 |
| Last Modified: | 19 Jul 2021 13:22 |
| URI: | https://fse.studenttheses.ub.rug.nl/id/eprint/25287 |
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