Exploring the Extreme Universe with High Energy Gamma Rays.
Felix Aharonian (Max-Planck-Institut fur Kernphysik, Heidelberg, Allemagne)

Jeudi 18 mars 2004

Very high energy gamma-ray astronomy is destined to play a crucial role in exploration of non-thermal phenomena in the Universe in their most extreme and violent forms. I will discuss the great potential of the discipline which allows impressive coverage of several areas of modern astrophysics, with emphasis on three "hot topics", in particular :

- 1. Origin of galactic Cosmic Rays :

The next generation gamma-ray instruments will soon allow us to answer the old-standing seminal question whether the strong shock waves in supernova remnants can accelerate galactic cosmic rays up to macroscopic energies of about one thousandth Joule

- 2. Physics and Astrophysics of Relativistic Jets :

Gamma rays from jets of Microquasars and Active Galactic Nuclei (AGN) provide unique information about the underlying physics of relativistic flows. An interesting implication of these studies is related to the possible origin of highest energy particles (observed in cosmic rays up to 100 Joule) associated with AGN jets or with solitary events like mysterious Gamma Ray Bursts.

- 3. Observational Cosmology :

Gamma-rays emitted by distant extragalactic objects effectively interact with photons of the Diffuse Extragalactic Background Radiation through cosmological information about the formation history and evolution of galaxies over cosmological epochs up to redshifts of about 10.