One of the major fields to be explored in the 21st century is the hard X-ray sky up to 50 keV or 100 keV. Above 10 keV, thermal components start to decay rapidly and then non-thermal power law continua become dominant. For example, some of SNR and Cluster of Galaxies exhibit substantial non-thermal components, which suggest high energy electrons. We would like to investigate acceleration mechanisms of such high energy particles by observing hard X-ray images and their spectra.
In order to perform imaging observations in hard X-ray range up to 50 k-eV, supermirror hard X-ray telescopes are most promising. We have studied to put Pt/C supermirror on the mirror shells of a high throughput X-ray telescope. The first satellite mission proposed with the supermirror hard X-ray telescope is our New X-ray Telescope mission (NeXT) in Japan to be launched 2010. 6-7 supermirror telescopes will be installed at the top of an extensible optical bench. The hybrid X-ray imager will be placed on the focal plane to observe hard X-ray images up to 50 keV with CdTe pixel detector underneath a thin CCD for soft X-ray imaging. For hi-h resolution spectroscopy, TES type calorimeters are considered without cryogen.
Non-imaging hard X-ray and soft gamma ray detector is studied to achieve unprecedented sensitivity between 50 and 300 keV. NeXT will be a sort of pathfinder of hard X-ray astronomy not only technically but also scientifically.