The Sky in Hard X-Rays

The first year of INTEGRAL observations has given several interesting results. A)The population of heavily obscured x ray sources was discovered in our Galaxy. It is analogous to the population of heavily obscured AGNs. B) The all sky observations of hard x ray sources continue. The first results gave a sample of low redshift sources which is significantly more abundant than observed in previous all sky surveys in the 20 60 keV spectrum band. C) Hard x ray emission is detected from several giant molecular clouds, but the SGR B2 cloud has the highest luminosity among them and has an unusually hard power law spectrum extended at least up to 150 keV. Together with ASCA, SAX and CHANDRA results, these observations prove that the observed x ray flux from SGR B2 results from the reflection of emission from SGR A* in the natural Compton mirror. This observation proves that the SGR A* black hole 400 years ago was a million times brighter in x rays than today and had an x ray spectrum typical for AGNs. D) The discovery of a gamma ray burst with luminosity orders of magnitude smaller than that of cosmological gamma ray bursts. Such intrinsically sub energetic events may occur very frequently in the Universe. E) Fine spectroscopy of the central part of the Galaxy in electron positron annihiliation line and properties of the interstellar matter where annihilation occurs. F) The main problems and future of the field.