Dear all, The general Physics colloquia will be given today by Edmond Giraud. This was arranged after the bulletin was mailed out. Title and abstract below. Apologies for the short notice, Ben
http://www-theorie.physik.unizh.ch/~moore/colloquia.html
Wednesday 9th April, 2003 General Physics Colloquium, 17hr, Y16G05, Irchel
Speaker: Edmond Giraud, Montpellier Title: The potential of gamma-ray telescopes for dark matter and cosmology
Abstract: Cosmological N-body simulations of cold dark matter have revealed the survival of a large number of substructures within galactic halos. For what concerns non baryonic matter, physics beyond the standard model may be supersymmetry. The galactic center (GC) and the dSphs have long been considered as the best candidates for indirect search of dark matter either because of its small distance (GC) or of their huge mass-to-light ratios (dSphs). Probing a large fraction of the supersymmetric parameter space by assuming that some of the galactic structures are made of neutralinos is one of the present day major scientific issues. Ground based gamma-ray telescopes based on Cerenkov images have the potential of exploring a significant fraction of the supersymmetric parameter space. A Cerenkov array can also serve as a major tool in Observational Cosmology and Astrophysics above 20-30 GeV. The satellite GLAST, which will be launched in 2006, will provide thousands of $\gamma$-rays sources locations down to a flux limit of $\rm 10^{-10}~\gamma~cm^{-2}~s^{-1}$, in a year of observation, which in turn will require a large ground-based instrument for studying these sources in reasonable exposure times. The goal of such an instrument will be to see the bulk of the cosmological AGNs up to z = 3 and to address the question of the infrared background. The gamma-ray burst afterglows will be observed with sufficiently high statistics as the high energy emission declines. This will also provide constraints on some quantum gravity theories.