Stury of interstellar and intergalactic media based on X-ray line spectra

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The purpose of this research is to observe X-ray emission from extended hot plasmas in the universe and to study their dynamical evolution. The research activity consists of four areas : observational study of galaxies and clusters of galaxies in X-rays, theoretical study of cosmic plasmas, building and testing of microcalorimeter instrument on-board Astro-E2, and development of TES microcalorimeter system for future spectroscopic observations. In the X-ray observation, ASCA and Chandra revealed that many clusters have experienced mergers based on the temperature and metallicity distribution of bright systems. It is hoped that Astro-E2 will detect significant gas motion in many clusters of galaxies. We have proposed a dedicated small X-ray mission to survey warm-hot intergalactic medium using Oxygen emission lines with an array of TES calorimeters. Theoretical study on the possible heat source for the cluster gas was performed. Microcalorimeters for Astro-E2 have been produced, and the ground tests showed that most of the pixels have energy resolution as good as 6 eV. We also contributed fabrication of filter wheel and software system. We also developed TES calorimeter array in collaboration with Waseda University, Seiko Instruments and Mitsubishi Heavy Industory. For a single pixel TES, we achieved energy resolution of 6 eV, close to the world record, and fabricated a test model of the array sensor with 256 pixels, which produced X-ray signals successfully. We also developed a small adiabatic demagnetization refrigerator system capable for calorimeter testings outside of the laboratory. Another new type of instrument, magnetic calorimeters, was also developed and produced signals to 5.5 MeV alpha particles.