Soft X-ray Mirrors onboard the NeXT satellite

摘要

The New Exploration X-ray Telescope (NeXT) is an X-ray astronomical observatory slated to be launched from Japan in 2013. Its objectives range from high resolution imaging and spectroscopy below keV to studying the hard X-ray sky up to ～70 keV. To accomplish these goals, it will carry, among other instruments, 4 grazing incidence, imaging telescopes, two covering the soft X-ray band and the remaining the higher energies. The soft X-ray telescopes will be similar to ones flown onboard Suzaku, with a larger outer diameter (45 cm) and longer focal length (6 m). The NASA's GSFC foil mirror group is collaborating with the Nagoya University and ISAS/JAXA in the implementation of the the soft X-ray mirrors. Our science driven goal is a <1.3' Half Power Diameter (HPD) Point Spread Function, improved from Suzaku HPD. We address important area in the fabrication process where we plan to make changes; (1) substrate shaping, (2) replication process, (3) reflector assembly, (4) alignment bar accuracy, and (5) focal length miss match among segments. Having done some of them, we measured 1.26' HPD for 60-pair quadrant reflectors. But it still includes bad sectors (>1.8' HPD) towards the quadrant boundary, while most of middle sectors are at 1' HPD level. The bad sectors can be corrected with new assembly approach where we actively tune and then fix reflectors at their right position or whole conical shell reflectors instead of segmented ones. In this proceeding, we present a proposed NeXT soft X-ray telescope performance, report the current status of the development and introduce the new whole shell mirror.