Within the field of astronomy, understanding how galaxies grow and evolve from the Big Bang to the present day is a challenging and complex question. Radio observations - unhindered by dust... Show moreWithin the field of astronomy, understanding how galaxies grow and evolve from the Big Bang to the present day is a challenging and complex question. Radio observations - unhindered by dust attenuation - are a powerful tool in studying the formation of stars and subsequent buildup of galaxies. In this thesis, the distant star formation is studied using radio observations from the VLA COSMOS-XS survey specifically. In Chapter 2, we discuss the details of the sensitive COSMOS-XS survey and present the derived Euclidean-normalized source counts. In Chapter 3, we derive the dust-unbiased star formation rate density out to high redshift and present evidence for a significant underestimation of the star formation rate density based on ultraviolet observations. In Chapter 4, the focus shifts to the ‘optically dark’ population: extremely dust-obscured sources that are invisible even in deep ultraviolet imaging. We identify these sources with the COSMOS-XS survey and use them to quantify their contribution to the total star formation rate density. In Chapter 5, we present new ALMA observations of ‘optically dark’ sources and confirm the cosmic importance of ‘optically dark’ sources at high redshift. Show less
Galaxies in the Universe are distributed along the intricate framework of the Cosmic Web. Groups and clusters of galaxies comprise the densest regions in this network, and therefore, are excellent... Show moreGalaxies in the Universe are distributed along the intricate framework of the Cosmic Web. Groups and clusters of galaxies comprise the densest regions in this network, and therefore, are excellent cosmic laboratories to study different aspects of galaxy evolution in extreme environments. In this thesis, we explore a wide range of properties of cluster galaxies and their host systems, such as the spatial distribution of mass in galaxies within clusters, the faint and diffuse stellar halo in groups and clusters, and processes that quench massive galaxies in high-redshift clusters. For this exploration, we develop methods to enable and optimise detailed comparisons of state-of-the-art observations and cosmological hydrodynamic simulations over more than half of the age of the Universe. Through our carefully-designed analyses, we test the validity of the simulations for studying the low-surface-brightness and high-redshift Universe. We also demonstrate how such comparisons can provide novel insights and motivate new tests for understanding galaxy evolution in dense environments. Show less
Outflows are crucially important for the gas budget and evolution of luminous star-forming galaxies and AGNs, with observed mass outflow rates of the same order as the star formation rate. Greater... Show moreOutflows are crucially important for the gas budget and evolution of luminous star-forming galaxies and AGNs, with observed mass outflow rates of the same order as the star formation rate. Greater star formation and black hole growth lead to more intense feedback and outflows, resulting in self-regulated galaxy growth. Multi-phase observations show that the cool molecular and atomic gas dominate the mass and momentum budget of massive galaxy outflows which additionally remove the direct fuel for star formation. In this thesis we target the molecular and atomic outflows at cosmic noon and dawn where the most extreme star formation and black hole activity is found but where current observations are severely lacking. Techniques commonly used to detect outflows in the nearby universe with emission lines are, however, challenging or impossible with current technology at the high-redshifts of this thesis. Molecular absorption lines provide a powerful and reliable alternative which is demonstrated with the OH+ and OH molecules in this thesis. With observations from the Atacama Large Millimeter/submillimeter Array (ALMA), this thesis provides cutting-edge comparisons of molecular/neutral outflows at cosmic dawn/noon between star-forming galaxies and dusty quasar hosts. Show less
Pérez-González, P.G.; Costantin, L.; Langeroodi, D.; Rinaldi, P.; Annunziatella, M.; Ilbert, O.; ... ; María Mérida, R. 2023