Junko Hiraga

Major research activity

JunkoHiragaResearch interest :X-ray Astronomy, Origin of the Elements, X-ray Imaging Spectroscopy

My research interest is observational study of the supernova remnants (SNR) utilizing X-ray imaging spectroscopy. In order to observe X-rays from the space, X-ray Astronomy satellites are needed because X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude. I participate in the JAXA’s ASTRO-H mission, which is an international collaboration project of the next X-ray space observatory.

A supernova remnant is the structure resulting from the explosion of a massive star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way. Shock heated materials become high temperature plasma of tens of millions degrees and shine brightly with X-rays. Heavy elements synthesized inside the star and propagated to the outer space by the supernova explosion and supernova remnants leave its traces for several hundred years.

The development of the X-ray detector in the laboratory for the future space mission is important, because a new discovery is achieved from a new detector. I am developing the next-generation X-ray imaging spectrometer, CMOS image sensor and SOI pixel detector. These detectors will carry out the observation with high timing resolution and of bright objects compared to that using by X-ray CCDs, which have been already a standard detector in the X-ray Astronomy.

Major relevant publications

  1. K. Makishima, T. Enoto,J.S.Hiraga, T. Nakano, K. Nakazawa, S. Sakuai, M.Sasano, and H.Murakami, Physical Review Letters, Volume 112, Issue 17, id.171102, (2014) “Possible Evidence for Free Precession of a Strongly Magnetized Neutron Star in the Magnetar 4U 0142+61”
  2. K.Hayashida, H.Tsunemi, T.G.Tsuru, T.Dotani, H.Nakajima. N.Anabuki, M.Ozaki, C.Natsukari,J.S.Hiraga, H.Tomida, T.Kohmura, H.Murakami, K.Mori, M.Yamauchi, I.Hatsukade, Y.Nishioka, A.Bamba, H.Uchida, M.Nobukawa, T.Tanaka, R.Nagino, S.Ueda, T.Fujinaga, T.Onishi, K.Matsuta and J.P.Doty, (2012) Proceedings of the SPIE, 8443, p.9- “Soft x-ray imager (SXI) onboard ASTRO-H”
  3. H. Yamaguchi, C. Badenes, R. Petre, T. Nakano, D. Castro, T. Enoto,J. S. Hiraga, J. P.Hughes, Y. Maeda, M. Nobukawa, S. Safi-Harb, R. Smith, H.Uchida, 2014, ApJL, 785, L27-32, (2014) “Discriminating the Progenitor Type of Supernova Remnants with Iron K-shell Emission”