ULTRA HIGH ENERGY COSMIC RAY
SOURCES &
EXPERIMENTAL RESULTS
Gustavo Medina Tanco
Instituto
de Astronomia, Geofísica e Ciências Atmosféricas
Universidade
de São Paulo, Brasil
Here we discuss the latest
developments in the debate, where the ultrahigh energy cosmic ray particles
come from. In this brief review, we emphasize the predictions that necessarily
follow from the various concepts proposed. We discuss both sources and
propagation, and spend some space on the by now most conservative model, giant
radio galaxies and their hot spots and jets, because it allows more steps in
the reasoning to be checked, and is more tightly constrained than any other
model. It has survived about forty years of debate already. We summarize the
task ahead of us at the end, including the development of new technologies to
observe ultra high energy cosmic rays, e.g., with the radio emission of air
showers, which may lead to an alternative to the fluorescence detectors with
their small duty cycle. Due to HiRes, AUGER, and the plans for EUSO, the future
is bright, and the ultra high energy cosmic ray particles may yet allow us to
explore new physics.