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David Vallés Pérez PhD Thesis defense

  • September 20th, 2024
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PhD Tesis defense

On the 26th of September, at 10:30 , in the classroom of the mathematics faculty, Burjassot, will take place the PhD thesis defense of David Vallés Pérez, that has been supervised by Susana Planelles Mira and Vicent Quilis Quilis.

Abstract:

"Unravelling the complexity of cosmic flows: strong gradients, shock waves and turbulence"

The formation and evolution of cosmic structures proceed through the gravitational collapse of primordial density fluctuations, which is a non-linear process that results in the emergence of the cosmic web and a rich hierarchy of structures. Besides gravity, many more phenomena associated with the physics of baryons are at play during this evolution and shape the physical and observational properties of galaxies, galaxy clusters and the environments they inhabit. The processes of cosmological structure formation are complex, in the sense of very non-linear, and involve a wide range of physical scales, making numerical simulations an indispensable tool for their understanding. 

The scientific goals of this Thesis have been mainly oriented towards the numerical study of the assembly of galaxy clusters, in the first place, and cosmic voids, in the second place, as two complementary ends of the range of cosmic structures. In galaxy clusters, the stirring of the gas due to accretion and mergers, together with other processes, generates two important non-linear hydrodynamic phenomena: shock waves and turbulence, which have a consequential impact on the dynamical, thermodynamical and observational properties of clusters. Regarding cosmic voids, although much of their interest comes from their role as pristine environments for galaxy evolution due to their mostly outflowing velocity field, the situation can be more complex in a cosmological context. 

The main results of this Thesis can be summarised in four closely intertwined main lines. The first line of work has been the development of numerical tools for the analysis of cosmological simulations of different types. The most salient outputs have been vortex, a code for performing a Helmholtz-Hodge decomposition of multiresolution velocity fields, and a new version of ASOHF, a spherical overdensity halo and galaxy finder. Both codes have been publicly released. The second line concerns the assembly of galaxy clusters, comprising two different works exploring the quantitative study of their accretion histories and the determination of the assembly state of dark matter haloes from a set of observables. A third axis of this Thesis is the study of the previously mentioned non-linear hydrodynamic phenomena, including the presence of turbulent motions in the intracluster medium in connection with its assembly history and the properties of cosmological accretion shock waves. Finally, the fourth line of work has been devoted to the study of the velocity field in cosmic voids, including the development of a new method for their identification in cosmological simulations.

PhD Thesis announcement