Dynamics of Galaxies

The Course offers an introductory overview to many important current themes that play a key role in the so-called "extragalactic astrophysics" and, in particular, to issues that relate the dynamics of galaxies, as studied in the nearby universe, to the problems of galaxy formation and evolution in the cosmological context. The course also addresses some fundamental questions that relate the description of complex self-gravitating systems in astrophysics to other interesting fields, such as plasma physics.
The main goal of the course is to demonstrate the merits of a semi-empirical approach to research. Starting from several substantial and concrete examples offered by extragalactic astrophysics, the student will learn and realize how the most interesting problems, also from the theoretical point of view, are identified from a wide and detailed phenomenological framework (thus, on the basis of modern observations from the ground and from space) and that excellent results in the astrophysics of complex systems such as galaxies derive from a rigorous formulation of relatively simple questions and models.
Course 1 is largely devoted to the study of problems and methods of investigations related to the dynamics of spiral galaxies.

At the end of the course, the student will master the following skills:


Will know the main structural and kinematical properties, as well as the main scaling laws, that characterize galaxies. With this empirical basis, will be able to undertake research in studies of formation and evolution of galaxies or research in the cosmological context in which galaxies are used as tracers on the grandest scale.
Will be able to calculate and evaluate the collision rate for stellar encounters in various astrophysical contexts, some of which (such as globular clusters or galactic nuclei) are of special interest in modern astrophysics.
Will be able to formulate fluid or kinetic models to study various questions related to the dynamics of stellar systems and some problems in plasma physics.
Will be able to identify and describe several simple orbital properties (precession, resonances) in many contexts, also in the field of celestial mechanics.
Based on the study of density waves as an explanation of the spiral structure in galaxies developed in this course, will be able to calculate various local and global properties of systems subject to dispersive waves, also with application to plasma physics and hydrodynamics.
In particular, will be able to solve problems that require the use of the approximation known as WKB.
Will also acquire a large body of examples that demonstrate the properties of equilibrium and mechanisms of instability in various dynamical contexts.