The Extreme sky

A critically important region of the astrophysical spectrum is the hard X-ray/gamma-ray band, from the keV to the GeV energy range. In this band, an unusually rich range of astrophysical processes occur: this is the energy domain where fundamental changes from thermal to non-thermal sources/phenomena are expected, where the effects of absorption are drastically reduced and a clearer picture of the Universe is possible. This is also the energy range where most of the extreme astrophysical behavior is taking place, e.g. cosmic acceleration, explosions and accretion onto black holes and neutron stars; where variability is more the rule than the exception and where a number of instruments are actively working (e.g. INTEGRAL, SWIFT, Suzaku, MAXI, AGILE, Fermi and HESS). These telescopes are providing an unprecedented view of the high energy sky. Combined with data obtained at lower energies from a number of satellites and ground based telescopes we have for the first time the possibility of studying this extreme and variable sky over a very broad energy band and with unprecedented sensitivity.The workshop is aimed at bringing together scientists active across the field of high energy astrophysics in order to focus on the opportunities offered by the high energy window both from the observational and theoretical viewpoints, while a dedicated section will also be devoted to discuss the current status of planned and future missions. The meeting will consist of invited talks and contributions which are welcome as either posters or as short presentations. There will be time for open discussions throughout.We intend to cover the most extreme phenomena associated with acceleration, explosions and accretion onto galactic and extragalactic objects as well as to study variability in all types of objects and environments. In view of the extension of INTEGRAL operational lifetime, the workshop will provide a unique opportunity to prepare for extra observational possibility and to start focusing on the INTEGRAL results for future missions.

All-sky surveys form the foundation of observational astronomy as they provide * statistics on the types and distribution of celestial objects which populate the Galaxy and the Universe * the ability to discover new classes of sources * a means of selecting specific types of objects for further studies/observations With respect to other surveys, those at high energies (above 10 keV) are particularly interesting as they probe the energy domain where fundamental changes from thermal to non-thermal sources/phenomena are expected, where the effects of absorption are drastically reduced, and a clearer picture of the Universe is possible. This is also the energy range where most of the extreme astrophysical behaviour is taking place, e.g. cosmic acceleration, explosions and accretion onto black holes and neutron stars. Recently a number of surveys have been performed in the keV to TeV energy range. The objective of this workshop is to gather all the knowledge collected so far above 10 keV, to compare and contrast the results obtained in the various bands in the light of physical models and ultimately provide indications for future progress. The meeting is aimed at bringing together scientists active across the high energy range in order to focus on the opportunities offered by this new window both from the observational and theoretical viewpoints, while a dedicated section will also be devoted to discuss future mission ideas. The meeting will consist of invited talks and contributions which are welcome as either posters or as short interventions. There will be time for open discussions throughout. Finally, this meeting is a perfect way in which to celebrate with friends and colleagues INTEGRAL's 7th birthday and 7 years of success in gamma-ray astronomy.