The INTEGRAL – HESS/MAGIC connection: A new class of cosmic high energy accelerators from keV to TeV

Abstract

The recent completion and operation of the High Energy Stereoscopic System [1], an array of ground based imaging Cherenkov telescopes, has provided a survey with unprecedented sensitivity of the inner part of the Galaxy and revealed a new population of very high energy gamma-rays sources emitting at E>100 GeV. Most of them were reported to have no known radio or X-ray counterpart and hypothesised to be representative of a new class of dark nucleonic cosmic sources. In fact, very high energy gammarays with energies E > 10 11 eV are the best proof of non-thermal processes in the universe and provide a direct in-site view of matter-radiation interaction at energies by far greater than producible in ground accelerators. At lower energy INTEGRAL has regularly observed the entire galactic plane during the first 1000 day in orbit providing a survey in the 20-100 keV range resulted in a soft gamma-ray sky populated with more than 200 sources, most of them being galactic binaries, either BHC or NS [5]. Very recently, the INTEGRAL new source IGR J18135-1751 has been identified as the soft gamma-ray counterpart of HESS J1813-178 [18] and AXJ1838.0-0655 as the X/gamma-ray counterpart of HESS J1837-069 [14].Detection of non thermal radio, X and gamma-ray emission from these TeV sources is very important to discriminate between various emitting scenarios and, in turn, to fully understand their nature.The implications of these new findings in the high energy Galactic population will be addressed.

15 years of Galactic surveys and hard X-ray Background measurements

“…In fact, high energy gamma-rays with energies E > 10 11 eV were, and actually are, the best proof of non-thermal processes in the universe and provide a direct in-site view of matter-radiation interaction at energies by far greater than producible in human-made accelerators. INTE-GRAL survey results were a powerful tool to immediately investigate the nature of this new type of galactic cosmic accelerator (Ubertini, 2005) thanks to the unprecedented INTE-GRAL/IBIS angular resolution and Point Source Location Capability of about 1-2 arcminute between 15 keV and a few MeV. Furthermore, INTEGRAL had already performed deep observations of almost all HESS detected sources: the new IN-TEGRAL source IGR J18135−1751 was identified as the soft gamma-ray counterpart of HESS J1813−178 (Ubertini et al, 2005) and AX J1838.0−0655 as the X/gamma-ray counterpart of HESS J1837−069 (Malizia et al, 2005), as shown in Fig.…”