- Docente: Carlo Nipoti
- Credits: 6
- SSD: FIS/05
- Language: Italian
- Teaching Mode: Traditional lectures
- Campus: Bologna
- Corso: Second cycle degree programme (LM) in Astrophysics and cosmology (cod. 8018)
Learning outcomes
The aim of the course is to provide the student with the fundamental tools to study the dynamics of gas in different type of galaxies and introducing some important astrophysical applications. At the end of the course the student will be familiar with the analytic modelling of hydrodynamic-equilibrium configurations of gas in galaxies and of hydrodynamic instabilities. In addition the student will have some knowledge of the role of magnetic fields in galactic gas dynamics and of the influence of some of the studied processes on the formation and evolution of galaxies.
Course contents
- Fundamentals of astrophysical fluid dynamics: mass, momentum and energy conservation, equation of state, gravity, cooling, heating,
thermal conduction.
- Main observed properties of gas in galaxies: disc galaxies
(neutral atomic gas, ionised gas, molecular gas), elliptical
galaxies (hot X-ray emitting gas, warm ionised gas, neutral gas).
- Equilibrium of gas in galaxies: self-gravity and external
gravitational potentials, hydrostatic equilibrium (isothermal,
adiabatic and polytropic distributions), virial temperature of a
dark-matter halo, 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 supermassive black holes (Bondi accretion, Eddington
limit).
- Magnetohydrodynamics (MHD) of gas in galaxies: MHD equations,
equilibrium of magnetised gas in galaxies, rotation and magnetic field, magnetosonic and Alfven waves, magnetorotational instability.
- Gas dynamics in galaxy formation and evolution: shock heating,
cooling of virial-temperature gas, hot and cold accretion modes,
star formation, feedback from stars and active galactic nuclei.
Readings/Bibliography
- 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
- F. Shu "The physics of astrophysics", 1992, University Science Books
- Landau, L. D., and Lifshitz, E. M. 1959. Fluid mechanics
- Binney, J., and Tremaine, S. 2008. Galactic Dynamics: Second Edition. Princeton 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
Other parts of textbooks and articles will be suggested during the lectures. Lecture notes will be made available to the students.
Teaching methods
Lectures
Assessment methods
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 both the theory of astrophysical gas dynamics and the applications to galaxies.
Teaching tools
Blackboard and projector.
Office hours
See the website of Carlo Nipoti