High energy astrophysics is now a crossover discipline tying the diverse fields of particle physics, astrophysics and cosmology. The Large Hadron Collider (LHC) will soon begin its exploration of TeV scale physics, whose results can profoundly affect the future development of cosmology and particle astrophysics. The recently-launched Fermi Gamma-ray Space Telescope has already detected numerous objects at GeV energies, including new pulsars and cosmological jet sources such as gamma-ray bursts and active galactic nuclei. Possible excesses of cosmic-ray electrons and positrons, recently indicated by PAMELA and ATIC/PPB-BETS, also connect dark matter physics and astrophysics. In the TeV gamma-ray sky, ground-based telescopes (HESS/MAGIC/VERITAS/MILAGRO) have successfully made many new discoveries, leading to dedicated plans for next-generation facilities (CTA/AGIS/HAWC). We are also witnessing the dawn of a new era of multi-messenger astronomy, utilizing not only photons but also cosmic-rays (Auger/TA), neutrinos (IceCube/ANTARES) and gravitational waves (LIGO/Virgo/GEO/LCGT/AIGO/LISA/DECIGO).
In these interdisciplinary fields, the role of accelerator laboratories are becoming ever more important, both technologically and scientifically, as exemplified by the Fermi experiment led by SLAC. In view of the difficulties in advancing the energy frontier in terrestrial experiments, this trend is expected to intensify along with future increases in energy scale and project size. Thus, the time is ripe to seriously consider how KEK can commit itself in this direction, including the iniation of large, experimental cosmophysics projects as its main activity on a 10-year time scale.
The aim of this workshop is to exchange ideas on some of the most fundamental problems in cosmophysics, such as the origin of cosmic particles and jets and the nature of dark matter, as well as to address the future of accelerator laboratories including KEK, by discussing the latest observational and theoretical developments in these fields with invited researchers from around the world.