The Cosmic Web describes the distribution of matter on the largest scales of the Universe. It is composed of dense regions full of galaxies, long filamentary structures and low density voids. In this thesis we introduce the Cosmic Web and we focus on the description of voids, large underdense regions pratically devoid of galaxies occupying the major volume of the Universe. Voids are a key component of the Cosmic Web, since their pristine environment is an important testing ground for our understanding of the importance of environmental influences on the evolution of galaxies. Then we introduce Voronoi and Delaunay tessellations, two random tessellation methods. Tessellation methods are used to divide a d-dimensional space into polytopes covering the whole space without overlapping. Voronoi and Delaunay tessellations are the basis of the DTFE method, useful when we want to compute a continuous field from a large point sample. Finally, we briefly discuss and compare two void finders: ZOBOV and WVF, whose aim is to find density depressions in a set of points, without introducing any free parameters.
Voids and the large-scale structure of the Universe
Picciano, Valentina
2017/2018
Abstract
The Cosmic Web describes the distribution of matter on the largest scales of the Universe. It is composed of dense regions full of galaxies, long filamentary structures and low density voids. In this thesis we introduce the Cosmic Web and we focus on the description of voids, large underdense regions pratically devoid of galaxies occupying the major volume of the Universe. Voids are a key component of the Cosmic Web, since their pristine environment is an important testing ground for our understanding of the importance of environmental influences on the evolution of galaxies. Then we introduce Voronoi and Delaunay tessellations, two random tessellation methods. Tessellation methods are used to divide a d-dimensional space into polytopes covering the whole space without overlapping. Voronoi and Delaunay tessellations are the basis of the DTFE method, useful when we want to compute a continuous field from a large point sample. Finally, we briefly discuss and compare two void finders: ZOBOV and WVF, whose aim is to find density depressions in a set of points, without introducing any free parameters.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/23829