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The cosmic ballet: spinning in the web

PhD ceremony:Ms P. (Punyakoti) Ganeshaiah Veena
When:October 16, 2020
Supervisors:prof. dr. M.A.M. (Rien) van de Weijgaert, prof. dr. E. Tempel
Co-supervisor:dr. M.C. Cautun
Where:Academy building RUG
Faculty:Science and Engineering
The cosmic ballet: spinning in the web

All the celestial objects, from small asteroids and planets to large galaxies and even the long filaments of the cosmic web are rotating. The origin of rotation is yet to be fully understood, especially in the context of galaxies and their dark matter haloes. In the young Universe, as matter began to clump together, the resulting anisotropic distribution of matter torqued up proto-galaxies. Simultaneously, the matter overdensities collapsed to form the large-scale filaments, clusters, walls and voids of the cosmic web that we see today. As a result, we expect a correlation between galaxy spin and the cosmic web.

In this thesis, we uncover the role of the cosmic web environment in establishing the rotation of haloes and galaxies using large cosmological simulations.We show that haloes in filaments are in general spinning faster than in other web components. We have studied the correlations between the spin-axis of haloes/galaxies with the orientation of the cosmic filaments that they are growing in. The thesis explores in detail the spin transition from parallel to perpendicular as a function of the halo or galaxy mass with respect to the spine of the host filament. We show how these trends evolve with cosmic time and filament properties using the MMF/Nexus and Bisous formalisms for cosmic web detection. The results from this thesis are important for various reasons. They not only hold information on how structure in the Universe emerged but also the notion of spin-transition mass promises to be a potential tool to probe the Universe.