High resolution spectroscopy of the X-ray emission of GRBs by IMXS-BOSS on the ISS

The IMXS (Interstellar and Intergalactic Medium X-ray Survey)-BOSS (gamma-ray Burst Observatory and Spectroscopy Survey) is an experiment proposed to fly on the ISS, in order to perform an all-sky X-ray survey with high spectroscopy resolution and to measure the spectra of Gamma-Ray Burst (GRB) with an high resolution in the 0.1-10 keV energy band. In a 3 years lifetime mission, the experiment will detect 20/40 GRBs. In several events, we can make an high energy resolution spectroscopy of the iron emission lines and absorption edges. Recently, such a components have been observed by BeppoSAX and CHANDRA. The measurements of this features would provide a direct diagnostic of the physical and kinematical state of the medium surrounding a GRB. Furthermore, they would supply informations about the origin of the progenitors of the GRBs (probably a supernova explosion of massive stars) and their site of formation (possibly a star-forming region)