X-Ray Observations of the Sagittarius D HII Region toward the Galactic Center with Suzaku

Makoto Sawada(1), Masahiro Tsujimoto(2), Katsuji Koyama(1), Casey J. Law(3), Takeshi Go Tsuru(1), Yoshiaki Hyodo(1)

(1) Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502
(2) Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, USA
(3) Astronomical Institute ``Anton Pannekoek'', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands

Paper: PASJ, in press

Weblink: http://www-cr.scphys.kyoto-u.ac.jp/member/sawada/paper/ms_SuzakuSgrD.pdf

EPrint Server: 0805.2079


We present a Suzaku X-ray study of the Sagittarius D (Sgr D) HII region in the Galactic center region. Two 18'*18' images by the X-ray Imaging Spectrometer (XIS) encompass the entire Sgr D complex. Thanks to the low background, XIS discovered two diffuse sources with low surface brightness and obtained their high signal-to-noise ratio spectra. One is associated with the core of the Sgr D HII region, arising from the young stellar cluster. The other is a new object in the vicinity of the region. We also present 3.5 cm and 6.0 cm radio continuum maps of the new source using the 100 m Green Bank Telescope. We conclude that the source is a new supernova remnant (SNR; G1.2-0.0) based on: (1) the 0.9+/-0.2 keV thermal X-ray spectrum with emission lines from highly ionized atoms; (2) the diffuse nature with an apparent extent of 10 pc at the Galactic center distance inferred from the X-ray absorption ( 8.5*1022 cm-2); and (3) the nonthermal radio continuum spectral index ( -0.5). Our discovery of an SNR in the Sgr D HII region leads to a revision of the view of this system, which had been considered to be a thermal HII region and its environment.

Preprints available from the authors at sawada@cr.scphys.kyoto-u.ac.jp , or the raw TeX (no figures) if you click here.

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