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PROJECT 7
X-ray Observations of the Hot Universe
Balloon Observations of Cosmic Anti-Protons
Researches using Data Acquired with Space-Borne Instruments
Instruments carried aloft by rockets, balloons, and satellites allow us to obtain valuable astrophysical knowledge that is unavailable by ground observations. Our project consists of the following two topics.

X-ray observations of the hot universe

We put an X-ray imaging spectrometer onboard the cosmic X-ray satellite ASCA launched in 1993. Subsequently, we have developed the Hard X-ray Detector, and put it onboard the Suzaku satellite (Figure 1). The HXD operates in the 10-600 keV energy range, thus providing us with valuable information on mass-accreting black holes, fast-rotating pulsars, supernova remnants, our Galactic center, active galactic nuclei, clusters of galaxies, and gamma-ray bursts.

Project7, figure 1
Figure 1 : The launch of the Suzaku X-ray observatory, by an M5 rocket from the Uchinoura Space Center at Kagoshima. It took place on 2005 July 10.

Balloon observations of cosmic anti-protons

Cosmic rays reaching the Earth contain a trace amount of anti-protons, which are produced in the interstellar space via cosmic ray collision with interstellar medium. However, lower-energy anti-protons may be produced via more exotic processes, including annihilation of heavy relic particles, or evaporation of primordial black holes. In search for such anti-proton components, we have been conducting a balloon experiment called BESS (Balloon Experiment with Superconducting Spectrometer) since 1993. It utilizes a specially developed superconducting solenoid for particle identification (Figure 2). We have already detected more than 1000 anti-protons, and we keep examining the data for any hint of excess anti-proton flux indicative of the exotic processes.

Project7, figure 2
Figure 2: The launch of a balloon carrying the BESS experiment, from Lynn Lake in Canada.