Accretion of Mass and Angular Momentum onto The Discs of Spiral Galaxies

Pezzulli, Gabriele (2015) Accretion of Mass and Angular Momentum onto The Discs of Spiral Galaxies, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Astronomia, 28 Ciclo. DOI 10.6092/unibo/amsdottorato/7237.
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In this Thesis, we study the accretion of mass and angular momentum onto the disc of spiral galaxies from a global and a local perspective and comparing theory predictions with several observational data. First, we propose a method to measure the specific mass and radial growth rates of stellar discs, based on their star formation rate density profiles and we apply it to a sample of nearby spiral galaxies. We find a positive radial growth rate for almost all galaxies in our sample. Our galaxies grow in size, on average, at one third of the rate at which they grow in mass. Our results are in agreement with theoretical expectations if known scaling relations of disc galaxies are not evolving with time. We also propose a novel method to reconstruct accretion profiles and the local angular momentum of the accreting material from the observed structural and chemical properties of spiral galaxies. Applied to the Milky Way and to one external galaxy, our analysis indicates that accretion occurs at relatively large radii and has a local deficit of angular momentum with respect to the disc. Finally, we show how structure and kinematics of hot gaseous coronae, which are believed to be the source of mass and angular momentum of massive spiral galaxies, can be reconstructed from their angular momentum and entropy distributions. We find that isothermal models with cosmologically motivated angular momentum distributions are compatible with several independent observational constraints. We also consider more complex baroclinic equilibria: we describe a new parametrization for these states, a new self-similar family of solution and a method for reconstructing structure and kinematics from the joint angular momentum/entropy distribution.

Tipologia del documento
Tesi di dottorato
Pezzulli, Gabriele
Dottorato di ricerca
Scuola di dottorato
Scienze matematiche, fisiche ed astronomiche
Settore disciplinare
Settore concorsuale
Parole chiave
galaxies: spiral galaxies: structure galaxies: evolution galaxies: accretion galaxies: star formation intergalactic medium interstellar medium: dynamics interstellar medium: abundances Galaxy: abundances hydrodynamics: barotropic equilibria hydrodynamics: baroclinic equilibria
Data di discussione
17 Dicembre 2015

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