X-rays from the HII regions and Molecular Clouds near the GC

Koyama, K1, Murakami, H2, Takagi, S1 and Senda, A1

1 Department of Physics, Kyoto University, Kyoto 606-8502, Japan
2 Institute of Space and Astronautical Science(ISAS), Kanagawa 229-8510, Japan

E-mail contact: koyama@cr.scphys.kyoto-u.ac.jp See: ApJ, 573, 275; ApJ 565, 1017; ApJ, 558, 687 (2001); ApJ, 550, 297 (2001)

Chandra reveals variety of X-ray sources in the molecular clouds (MC) and HII regions (HII), Sgr B2, Sgr C, M0.11-0.08, Arches, Quintuplet and the Galactic center clusters.

We found moderately bright X-ray sources from Sgr B2, Quintuplet and the Galactic center clusters at the position of ultra compact HIIs (UCHII) or bright infrared sources. The X-ray spectra are fitted with a thin thermal plasma model of 2-10 keV temperature, with luminosity of about 10^32-33 ergs/s. The X-ray properties are typical to those of high-mass young stellar objects (YSO) or YSO clusters. The Arches cluster has 3 bright X-ray sources, at the position of bright IR and radio stars, with the total luminosity of a few times 10^34 ergs/s. The high luminosity may indicate unusual X-ray emission mechanism for these high mass YSOs.

A unique X-ray features of MC and HII near the Galactic center (GC) is the presence of diffuse X-rays with strong 6.4 keV lines; those of Sgr B2 and Sgr C would be attributable to the fluorescence irradiated by external sources at the GC side. The diffuse X-rays from Arches are likely to be the irradiation of internal bright X-rays YSOs. M0.11-0.08 is very complex in diffuse X-ray with many clumps of size of different spectra and morphology; some show the 6.7 keV line, the others are the 6.4 keV line emitters with filamental morphology.

We report the details and discuss the nature of these X-ray sources.