In this thesis, we present new laboratory data of interstellar dust analogues. These measurements, were transformed to interstellar dust models and were used to fit the spectra of low-mass X... Show moreIn this thesis, we present new laboratory data of interstellar dust analogues. These measurements, were transformed to interstellar dust models and were used to fit the spectra of low-mass X-ray binaries located in the Galactic center neighborhood in order to determine the dust properties along those lines of sight. In these spectra, we focus in particular on the Si K-edge. The XAFS features in the Si K-edge offer a range of possibilities to study silicon-bearing dust, such as investigating the crystallinity, abundance and the chemical composition. We also present a study on the prospects of observing carbon, sulfur, and other lower abundance elements (namely Al, Ca, Ti and Ni) present in the interstellar medium using future X-ray instruments. We simulated data of instruments with characteristics of resolution and sensitivity of the Athena, XARM and Arcus concepts. Lastly, we explore the theory of X-ray scattering for a new parameter space where the small angle approach is no longer valid and where the size distribution of the dust includes large (> 1 micron) particles. We apply this theory to the environment of stellar debris disks where such conditions apply. We use as a best test case the debris disk of AU Microscopii. Show less
Laboratory, observation and modeling work on the dissociation of polycyclic aromatic hydrocarbons in interstellar environments and the formation of new molecular species through the fragmentation... Show moreLaboratory, observation and modeling work on the dissociation of polycyclic aromatic hydrocarbons in interstellar environments and the formation of new molecular species through the fragmentation process. Show less
In this thesis we used numerical simulations to explore the role that chemistry plays in galaxy formation. Simulations of galaxies often assume chemical equilibrium, where the chemical reactions... Show moreIn this thesis we used numerical simulations to explore the role that chemistry plays in galaxy formation. Simulations of galaxies often assume chemical equilibrium, where the chemical reactions between ions and molecules have reached a steady state. However, this assumption may not be valid if the physical conditions of the gas are evolving rapidly. Therefore, we developed a chemical model to follow the non-equilibrium evolution of ions and molecules. We then incorporated this model into hydrodynamic simulations of galaxies. We ran simulations with different metallicities (i.e. different proportions of heavy elements) and UV radiation fields, first using our full non-equilibrium chemical model and then assuming chemical equilibrium. We found that the total star formation rate is higher at higher metallicity and for weaker radiation fields. In contrast, non-equilibrium chemistry does not strongly influence the total star formation rate or outflow properties of the galaxy. However, it does affect the abundances of individual chemical species, for example in molecular outflows. Finally, we explored the properties of molecular clouds in our simulations. At low metallicity, the molecular fraction of young clouds tends to be below equilibrium, as the molecules are still forming. This also affects the observable CO emission from young clouds. Show less
