RADIOASTRONOMY

The objective of the Radioastronomy course is to provide a clear overview of the most important reseaches in this field, of the instruments and to the future perspectives.

Frontal lectures where, beside the illustration of the most important researches in Radioastronomy and of the emission processes and propagation effects, simple computations useful to derive important papameters of the radio sources, with the aim to address the student towards the research.

1. Introduction to Radioastronomy. Historic overview, the radio window.
2. The EM radiation– Intensity, Brightness, Flux density, Planck law, Brightess temperature, Approximations at radio wavelengths, Brightness Temperature, Radiative transfer, EM waves in vacuum, Energy of EM field, Propagation of EM waves in a plasma, Plasma frequency, Ionosphere, Dispersion measure, Dispersion measure with Pulsars, Polarisation of EM waves, Faraday rotation, Galactic magnetic field, the radiation spectrum, Electromagnetic potentials, Retarded potentials, Radiation from a single charge, non-relativistic case, Dipole radiation, Dipole approximation
3. Bremsstrahlung radiation (free-free), emission and absorption coefficients, Spectra, Example of Bremsstrahlung radio source: NGC7027
4. Synchrotron radiation, emission and absorption coefficients, Spectra, Energy requirements for synchrotron radio sources, Example of Synchrotron radiosources: Cyg-A, Cas-A – Thomson scattering, Inverse Compton– Sunyaev Zeldovich (SZ) effect
5. Radiotelescopes, Antenna beam, Antenna configurations and mounts, Antenna temperature and brightness temperature, aperture efficiency, telescope gain, effects of Earth’s atmosphere, The receiver system, super-heterodyne receiver, system temperature and sensitivity
6. Interferometry – Basic Theory and theorem of Van Cittert Zernike – Visibility function and sky brightness – Linear Interferometers (WSRT, ATCA)- Angular Resolution of an interferometer– Aperture Synthesis – The mapping process- Interferometers in the world (VLA, VLBI, VLBA, ALMA, SKA)
7. Example of radio sources: Supernovae and Supernovae remnants (SNR) – Shock waves – Fermi Acceleration (first order), Microquasars, superluminal motions, Doppler boosting, Star Forming Regions (HII) –Strömgren sphere

1. Rybicki and Lightman, Radiative Processes in Astrophysics, John Wiley & Sons, Inc (1979)
2. Rohlfs, Tools of Radio Astronomy, A&A library, Springer-Verlag
3. Burke and Graham-Smith: An Introduction to Radio Astronomy, Cambridge University Press, (1977, 2002)
4. Longair: High Energy Astrophysics, Vol. 1, Cambridge University Press
5. Verschuur and Kellermann eds, Galactic and Extragalactic Radio Astronomy, A&A library, Springer-Verlag