69052 - High Energy Astrophysics

Learning outcomes

This course focuses on the high-energy (X-ray and Gamma-ray) emission from populations of Galactic and extra-galactic sources.

The student is expected to attain a good knowledge of the techniques related to the detection of X-ray and Gamma-ray photons and on the properties of past and present X-ray telescopes. Students will be able to critically discuss the high-energy emission phenomena and the properties of compact X-ray sources, mostly X-ray binaries and Active Galactic Nuclei (AGN), and extended X-ray sources, with particular emphasis on the Galactic Center region.

Course contents

INTRODUCTION TO HIGH-ENERGY ASTROPHYSICS

• Recap on emission mechanisms: blackbody/bremsstrahlung/synchrotron/Compton scattering and Inverse Compton scattering, and some examples in the field of high-energy Astrophysics. Line production; collisional and ionization equilibrium.

• History of the high-energy Astronomy. Excursus on the properties of the main X-ray/Gamma-ray satellites of the 'golden age'.

• Detection techniques for high-energy photons. X-ray and Gamma-ray detectors; CCDs in X-rays. Wolter-type telescopes and coded-aperture masks. Cerenkov radiation.

 

ACCRETION PHYSICS:

• Theory, Eddington limit, accretion discs. Accretion and ejection processes (jets, winds)

• Physics of compact objects: white dwarfs, neutron stars, Chandrasekhar limit, pulsars, black holes (with some mentions on relativistic astrophysics)

HIGH-ENERGY ASTROPHYSICS: GALACTIC

• X-ray emission from Solar System objects.

• Stellar X-ray Astronomy: main-sequence (MS) and pre-MS stars/very low-mass stars.

• X-ray binaries:  phenomenology, classification and physical properties. Cataclysmic variables,Low- and High-mass X-ray binaries, candidates black holes.
  

• The Galactic Center: a multi-wavelength perspective. Emission from point-like and extended X-ray/Gamma-ray sources. Properties of the Fermi bubbles and other extended features. Matter infalling onto SgrA*.

• Ultraluminous X-ray sources
  

 

HIGH-ENERGY ASTROPHYSICS: EXTRA-GALACTIC

• Clusters of galaxies and cooling flows
  

• Active Galactic Nuclei (AGN): X-ray spectral components in X-rays: models vs. observations.  

• X-ray surveys in the last decade. AGN contribution to the cosmic X-ray background. Open issues.

• Gamma ray bursts: phenomenologies, origin and emission mechanisms
  

Readings/Bibliography

• George B. Rybicky, Alan P. Lightman: "Radiative Processes in Astrophysics", Wiley

• Malcolm S. Longair: "High-Energy Astrophysics", Cambridge University Press

• J. Frank, A. King & D. Raine: "Accretion Power in Astrophysics", Cambridge University Press

• Gabriele Ghisellini: "Radiative processes in high energy astrophysics", Springer, Lecture Notes in Physics 873

The slides used during the lectures will be made avaailable, too.

Teaching methods

Lectures with the aid of slides and blackboard. From time to time, during the lecture we will  critically analyze recent publications and/or reviews on the lecture topics. Time will also be devoted to "questions and answer" sessions at the end of the macro-topics.

Assessment methods

Oral exam where the candidate should demonstrate to have an organic view of the discipline. The exam will start with a topic chosen by the student. The candidate should be able to deduce relations among physical quantities related to high-energy astrophysics in a non mnemonic way.

Teaching tools

Blackboard and presentations of powerpoint slides.

Office hours

See the website of Marcella Brusa