- Docente: Daniele Dallacasa
- Credits: 9
- SSD: FIS/05
- Language: Italian
- Teaching Mode: Traditional lectures
- Campus: Bologna
- Corso: First cycle degree programme (L) in Astronomy (cod. 8004)
Learning outcomes
At the end of the lectures each student will possess a
comprehensive knowledge of the astrophysical processes generating
photons at various locations in the Universe (stars, star forming
regions and interstellar medium, galaxies, intergalactic medium,
hot plasma, etc.) in a range of physical conditions (temperature,
density, pressure, etc.). In particular every student will be able
to interpret the emitted spectrum of any celestial body, and then
infer the processes responsible for the generation of the observed
photons, and derive the main astrophysical quantities such as,
density, temperature, magnetic field, energy content, pressure,
etc.
Students will be also familiar with general concepts concerning
astrophysical fluids and plasmas (with magnetic fields). *IT IS
VERY IMPORTANT that the student already has passed the exam FISICA
GENERALE II, for a fitful study of this course.
Course contents
Summary of principles of hydrostatics. Fundamentals of
hydrodynamics: equations of conservation of mass, of Euler or Navier-Stokes, conservation of energy in a fluid. Sound
waves; shock waves - Fundamentals of Magneto-Hydro-Dynamics (MHD):
magnetic forces, fields frozen in the matter; Alfven waves. Origin
of magnetic fields in astrophysics. Radiative transfer in
astrophysics- Continuum emission processes. Black body and the Plank's function. Properties. Stars as Black Bodies. Color Index and the H-R Diagram. Thermal and
relativistic bremsstrahlung, cyclotron and synchrotron radiation.
Photon-electron scattering, Thomson, Compton and Inverse Compton.
Sunyaev-Zeldovich effect. Wave propagation in a plasma: dispersion
measure; Faraday rotation. Particle acceleration in astrophysics
(Fermi mechanism): stochastic and systematic acceleration - Cosmic
rays: general properties, composition and origin - The InterStellar
Medium; the role of the dust. Statistical laws and thermodynamic
equilibrium; detailed statistical equilibrium, Einstein's
coefficients for radiations and collisions; population of energy
levels in the ISM. Emission and absorbption in atoms and molecules
(HI, CO, CN). Determination of the temperature and density from
line spectra. =
A number of simple astrophysical problems will be discussed and
solved, to prepare the students for the test of admission to the
oral exam.
Readings/Bibliography
- M.S. Longair: "High energy Astrophysics" - Cambridge University Press (English)
- Rybicki & Lightman "Radiative processes in astrophysics" - Wiley (English)
- C. Clarke & Carswell "Principles of Astrophysical Fluid Dynamics", Cambridge University Press (English)
Further lecture notes will be illustrated in the lectures.
Teaching methods
Lectures, in which it will be discussed how information on fundamental physics and gas thermodynamics are derived from simple astronomical measurements. A number of astrophysical examples will be discussed, in the light of the role of the basic astrophysical processes in producing the radiation observed. Some simple application (exercise) will show how to take advantage of the concepts faced during lectures.
Assessment methods
A 90-min written test composed by 4 questions (at least 2 in an open
form) allows the admission to the oral exam. During the written
test it is possible to use lecture notes and books. The test possible
outcomes are: admitted, partial admission, not admitted. The final
grade will be defined after the oral exam. This latter is made of three main questions (~15' each) in which the candidate is supposed to describe the main subjects seen during the lectures.
In case of Covid-related restrictions, there will be a short test in which the candidate will be asked to solve a simple problem, before proceeding to the oral test.
Teaching tools
Slide projector (from a notebook - copy of the slides is available
to students on the website); also a blackboard will be used, also for solving problems like the ones in the final test.
Links to further information
http://www.ira.inaf.it/~ddallaca/P-RAD.html
Office hours
See the website of Daniele Dallacasa