Hard X-ray focusing optics up to 80 keV for the future missions

• Published in: Advances in space research Vol. 34; no. 12; pp. 2682 - 2687
• Main Authors: Okajima, T., Tawara, Y., Ogasaka, Y., Tamura, K., Furuzawa, A., Yamashita, K., Kunieda, H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2004
• Subjects: Hard X-ray telescopes; Multilayers; Supermirrors; X-ray astronomy; Multilayers; X-ray astronomy; Hard X-ray telescopes; Supermirrors
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2003.03.057

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 cm 2 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.