Oană, Răzvan (2026) Dynamics of the Cosmic Web. Bachelor's Thesis, Astronomy.
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Abstract
The spatial distribution of matter on the Megaparsec (Mpc) scale forms a complex network known as the Cosmic Web. While the initial stages of its evolution from primordial density perturbations are well described by the Zel'dovich approximation (ZA), its later non-linear dynamics require further scrutiny. In this thesis, we investigate the overall evolution of the dark matter Cosmic Web, mass migration between its environments (nodes, filaments, walls, and voids), and the validity of the ZA during late-stage structure formation. Using the TNG50-4-Dark cosmological simulation, we extract the density field at various redshifts via the phase-space Delaunay Tesselation Field Estimator (PS-DTFE) and classify environments using the NEXUS+ algorithm. Our analysis reveals how mass and volume are partitioned between the Cosmic Web environments across time. Dramatic mass migration occurs around z = 2, broadening the density distribution towards the extremes and fueling the development of multi-stream regions. By tracking individual particles in Lagrangian fashion, we show that mass elements ending up in nodes at z = 0 follow the expected void-wall-filament-node trajectory. Particles not following this path likely trace void substructure. Finally, we demonstrate that the ZA remains perfectly valid up to z = 5 but fully breaks down by z = 2. Surprisingly, particles in present-day nodes deviate least from the ZA. We speculate this is a by-product of virialization, warranting future study.
| Item Type: | Thesis (Bachelor's Thesis) |
|---|---|
| Supervisor name: | Weijgaert, M.A.M. van de and Alferink, B.D. |
| Degree programme: | Astronomy |
| Thesis type: | Bachelor's Thesis |
| Language: | English |
| Date Deposited: | 21 Jul 2026 07:18 |
| Last Modified: | 21 Jul 2026 07:18 |
| URI: | https://fse.studenttheses.ub.rug.nl/id/eprint/37453 |
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