Institution: | a Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA b Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan c The Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan |
Abstract: | X-ray telescopes have been providing high sensitivity X-ray observations in numerous missions. For X-ray telescopes in the future, one of the key technologies is to expand the energy band beyond 10 keV. We designed depth-graded multilayer, so-called supermirrors, for a hard X-ray telescope in the energy band up to 40 keV using lightweight thin-foil optics. They were successfully flown in a balloon flight and obtained a hard X-ray image of Cyg X-1 in the 20–40 keV band. Now supermirrors are promising to realize a hard X-ray telescope. We have estimated the performance of a hard X-ray telescope using a platinum–carbon supermirror for future satellite missions, such as NeXT (Japan) and XEUS (Europe). According to calculations, they will have a significant effective area up to 80 keV, and their effective areas will be more than 280 cm2 even at 60 keV. Limiting sensitivity will be down to 1.7 × 10?13 erg cm?2 s?1 in the 10–80 keV band at a 100 ks observation. In this paper, we present the results of the balloon experiment with the first supermirror flown and projected effective areas of hard X-ray telescopes and action items for future missions. |