ASTROPHYSICS

Course objectives

GENERAL OBJECTIVES: The course is a general introduction to astrophysics. It aims at the description the most important physical mechanisms and phenomena at work in the universe: stellar, interstellar, galactic, extragalactic and cosmological. The focus is on the modelling of astrophysical and cosmological phenomena, and on the use of physical laws in the interpretation of astrophysical and cosmological observations. SPECIFIC OBJECTIVES: A - Knowledge and understanding OF 1) To know the stellar phenomenology and understand it in terms of the different physical mechanisms of energy production. Understand the stellar evolution, as described by the fundamental equations of stellar structure. OF 2) To know the phenomenology of the insterstellar medium (plasmas, gases, dust) and understand it in terms of physical mechanisma of emission and absorption. OF 3) To know the phenomenology of the Galaxy and of the galaxies in the universe, and understand it in terms of the physical phenomena at work. OF 4) To know the cosmological phenomenology, the observables and their use in the development of a physical model of the universe at large scales. To understand the cosmological evolution of the universe in the homogenous isotropic approximation using physics and in particular gravitation. B - Application skills OF 5) To be able to explain astrophysical and cosmological measurements, and use them to constrain the physical model of the system under study, understanding its nature. C - Autonomy of judgment OF 6) To master the acquired know-how, and use it in the solution of basic problems in astrophysics and cosmology, and in the understanding of the specialized literature. D - Communication skills E - Ability to learn OF 7) To be able to understand specialistic papers in order to deepen the knowledge of particular topics introduced during the course.

Channel 1
PAOLO DE BERNARDIS Lecturers' profile

Program - Frequency - Exams

Course program
Part 1) Stars : Production of energy in the stars: Nuclear Potential. Nuclear fusion reactions. Gamow peak. Equations of stellar structure. The photosphere: Spectroscopic Method, Stellar spectra: examples, Harvard classification. Spectral lines in stellar spectra. Population of energy levels and ionization versus photospheric temperature. Physical interpretation of the spectra of stars. Part 2) Interstellar medium: Macroscopic description of the light-matter interaction. Emission, Absorption, Scattering. Optical depth. Radiative transfer equation. Thermal radiation. Blanckbody radiation. Isothermal atmosphere. Earth atmosphere, millimeter-wave windows, ground-based measurements of the CMB. Emission and absorption lines. Einstein coefficients. Thermal vs non-thermal emission. Scattering and random-walk. Scattering and absorption. Scattering of phontons in the sun. Interaction of photons and electrons. HII regions. Thomson and Compton scattering. Last Scattering Surface. Rayleigh Scattering. Why the sky is blue. Interaction between photons and solid particles. Interstellar dust. Depth of absorption lines. Curve of growth. Measurement of the abundance of elements. The interstellar extinction curve. Q_abs. Interstellar dust emission. Temperature of the grains. Polarization of interstellar dust emission and absorption. Mass estimates from dust emission measurements - the case of RCW38. Non thermal radiation. Cyclotron, synchrotron - spectra and their dependence on the energy distribution of electrons. Galactic synchrotron. Polarization measurements. Free-free radiation. Interstellar Gas. Neutral Hydrogen in our Galaxy. Part 3) the Galaxy and the galaxies: Star formation. Jeans mass. collapse and fragmentation of gas clouds. formation of protostars. molecular hydrogen. 21 cm line. Rotation curves of galaxies. optical measurements of the rotation curve. evidence for dark matter in galaxies. dark matter in galaxy clusters. virial mass. the case of Coma. M/L ratio. Additional evidence for dark matter (deflection of light - lensing, intergalactic gas in galaxy clusters, etc.). WIMPs. The galaxies. measurement of distances in astronomy. astrometry. luminosity distance. absolute HR diagram. distance to the LMC. cepheids. supernovae. pulsars. galaxies as standard candles, Tully-Fisher method. Measurements of redshift. Hubble's law. 3-D distribution of galaxies. Hubble's law from measurements of angular diameter. physical interpretation of the redshift. Part 4) Cosmology: Isotropy and homogeneity of the universe at large scales. Copernican principle. Isotropy, homogeneity and Hubble's law. Cosmological principle. Expansion of the universe and density. scale factor. Friedmann equation. density parmaeter. curvature. Einstein equations.different forms of mass-energy, and Friedmann equation: non-relativistic matter, radiation, cosmological constant. deceleration parameter. Hubble's diagram. Luminosity distance. Evolution of a homogeneous and isotropic universe. radiation phase. matter phase. vacuum phase. evolution of a black-body spectrum in an expanding universe. Radiation and relativistic matter. Evidence for the cosmological origin of the cosmic microwave background (CMB). The components of the universe. matter, baryonic and dark. age of the universe. anisotropy of the CMB and structures in the universe.
Prerequisites
a) Knowledge of geometry and calculus, as studied in the classes of geometry, analysis, vector analysis. b) Knowledge of mechanics, as studied in the classes of mechanics and analytic and relativistic mechanics. c) Knowledge of electromagnetism, as studied in the homonym class.
Books
class slides and exercises at https://meet.google.com/gtk-svko-nnv Specific parts of : Bradley W. Carroll, Dale A. Ostlie, An introduction to modern astrophysics, Addison Wesley, 1996. Codice Biblioteca: 523,03 Carr James Rich, Fundamentals of Cosmology, Springer, 2001 Codice Biblioteca: 523.1 Rich
Frequency
presence in the classroom not madatory, but is strongly recommended
Exam mode
written test (or two test during the class) and oral exam on the program.
Lesson mode
classroom lectures and exercises two tests during the class and general discussion on the solutions
  • Lesson code1038469
  • Academic year2024/2025
  • CoursePhysics
  • CurriculumAstrofisica
  • Year3rd year
  • Semester1st semester
  • SSDFIS/05
  • CFU6
  • Subject areaAstrofisico, geofisico e spaziale