Velocity Fields: probes and agents of Cosmic Web evolution

Mast, M. van de (2016) Velocity Fields: probes and agents of Cosmic Web evolution. Master's Thesis / Essay, Astronomy.

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Abstract

We have studied the density and velocity fields from the Cosmogrid simulation (Ishiyama et al., 2013). Our methods include a Delaunay Tessellation Field Estimation (DTFE) of density and velocity fields from the simulation particles. We decomposed the velocity gradient into divergence, shear and vorticity, and classified six different components of the cosmic web on the basis of the eigenvectors of the deformation tensor. This thesis presents the spatial and statistical distributions of these quantities, and a decomposition of these fields into the contributions from different web components. We have studied the correlations between density and various velocity-related quantities, and followed the redshift evolution of parameters for the lognormal fits to the statistical distributions. From these results, we find various forms of evidence for hierarchical evolution of cosmic structures; we determine the extent to which density and velocity divergence are correlated; we explore the formation and interactions between different structures that make up the cosmic web; we specifically probe the evolution of anisotropic structures; and follow the time evolutions of density, divergence, shear and vorticity. Lastly, we have identified a few artefacts resulting from the data and methods; and we assert the merit of the DTFE algorithm.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Astronomy
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:12
Last Modified:	15 Feb 2018 08:12
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/13871

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