Ocupación de halos y propiedades de las galaxias en la Red Cósmica : análisis en nodos y filamentos de Illustris TNG

Abstract

Abstract The distribution of galaxies that we observe in the current universe is the result of a hierarchical evolution process, driven by the growth of small primordial perturbations inthe density field ofthe early universe.Asmatter collapses underthe influence of gravity, the large structures of the cosmos are formed: filaments, nodes, and voids, which constitute the Cosmic Web. Understanding the connection between the properties of galaxies and the environment in which they are found is key to unraveling the mechanisms that regulate their formation and evolution. This thesis studies various properties of the distribution of galaxies within these cosmic structures, using the Illustris TNG 300 hydrodynamic simulations. In particular, it analyzes how the Halo Occupation Distribution (HOD) varies depending on the environment, and how observable properties of galaxies, such as stellar mass, color, and star formation rate, relate to the characteristics of their surrounding environment. Another central focus of the work is the study of galactic conformity, i.e., the correlation between the properties of central galaxies and those of their neighbors, and how this signal is modulated by the environment. Likewise, the temporal evolution of the clustering and some galactic properties between z = 2 and z = 0 is investigated. To address these issues, a parametric model of the HOD is implemented, whose evolution is analyzed as a function of different parameters, and alternative methodologies for its adjustment are explored, including optimization techniques and Bayesian methods. The results obtained show significant differences in the HOD and in the evolution of galaxies depending on the type of environment, as well as a signal of conformity that is reinforced under certain conditions. Taken together, these findings provide a deeper understanding of the role played by the cosmic environment in the evolution of galaxies. The thesis is organized into six chapters. Chapter 1 presents the necessary theoretical framework, including the formation of large-scale structures and the concept of HOD. Chapter 2 describes the simulations and data used. Chapter 3 analyzes halo occupation in different environments, while Chapter 4 focuses on galactic conformity. Chapter 5 addresses the temporal evolution of clustering and galactic properties. Finally, Chapter 6 presents the implementation and analysis of the fiveparameter model for the HOD. The general conclusions close the work in Chapter 7, with a final reflection on the main contributions made and possible future lines of research.