69055 - DINAMICA DEL GAS NELLE GALASSIE

Conoscenze e abilità da conseguire

Lo scopo del corso è di fornire allo studente gli strumenti fondamentali per studiare la dinamica del gas nei diversi tipi di galassie e di introdurre alcune importanti applicazioni astrofisiche. Al termine del corso, lo studente ha dimestichezza con i principali modelli analitici che descrivono l'equilibrio idrodinamico del gas nelle galassie e le instabilità idrodinamiche. Possiede infine una conoscenza di base del ruolo dei campi magnetici nella dinamica del gas nelle galassie e dell'influenza di alcuni dei processi studiati sulla formazione ed evoluzione delle galassie.

Contenuti

- Fundamentals of astrophysical fluid dynamics: mass, momentum and energy conservation, equation of state, gravity, cooling, heating,
thermal conduction, viscosity and turbulence .

- Equilibrium of astrophysical fluids: self-gravity and external
gravitational potentials, hydrostatic equilibrium (isothermal,
adiabatic and polytropic distributions), virial temperature, isothermal self-gravitating plane layer, self-gravitating isothermal gas sphere, rotating equilibrium (barotropic and baroclinic distributions), thin and thick discs.

- Hydrodynamic stability and instability: Eulerian and Lagrangian
perturbations, linear and non-linear perturbations, sound waves,
gravitational (Jeans) instability, convective (Schwarzschild)
instability, rotation (Rayleigh) instability, Solberg-Hoiland
criterion, thermal instability, Toomre instability.

- Gas flows in galaxies: steady inflows and outflows, shocks, gas
accretion onto black holes (Bondi accretion, Eddington limit).

- Astrophysical magnetohydrodynamics (MHD): MHD equations,
equilibrium of magnetised gas, Ferraro's law of isorotation, magnetosonic and Alfvén waves, magnetorotational instability.

Testi/Bibliografia

- M. J. Thompson "An introduction to astrophysical fluid dynamics", 2006, Imperial College Press

- J. Pringle and A. King "Astrophysical flows", 2014, Cambridge University Press

- C. Clarke and B. Carswell "Principles of Astrophysical Fluid Dynamics", 2014, Cambridge University Press

- A. Cimatti, F. Fraternali and C. Nipoti, "Introduction to Galaxy Formation and Evolution. From Primordial Gas to Present-Day Galaxies", 2019, Cambridge University Press

- F. Shu "The physics of astrophysics", 1992, University Science Books

- Binney, J., and Tremaine, S. 2008. Galactic Dynamics: Second Edition. Princeton University Press.

- Landau, L. D., and Lifshitz, E. M. 1959. Fluid mechanics

Specific sections of textbooks and articles will be suggested during the lectures. Lecture notes will be made available to the students.

 

Metodi didattici

Lectures

Modalità di verifica e valutazione dell'apprendimento

The assessment method will be based on an oral exam in which the
student will be asked to answer three questions about three different
topics among those presented during the lectures. The oral exam
is aimed at verifying the knowledge of the theory of fluid dynamics phenomena and the understanding of the main astrophysical applications.

Strumenti a supporto della didattica

Blackboard and projector.

Orario di ricevimento

Consulta il sito web di Carlo Nipoti