X-Ray Reflection Nebulae with Large Equivalent Widths of Neutral Iron K-alpha Line in the Sgr C Region

摘要

We report on the results of the Suzaku observation in the Sgr C region, vicinity of the Galactic Center where there are giant MCs. We detected four diffuse clumps with strong line emission at 6.4 keV, Kalpha from neutral or low-ionized Fe. The X-ray spectra of the two bright clumps, exhibit strong Kalpha line from Fel with large equivalent widths (EWs) of 2.0-2.2 keV and clear Kbeta of Fel. The GCDX in the Sgr C region is composed of the 6.4 keV- and 6.7 keV-associated components. These are phenomenologically decomposed by taking relations between EWs of the 6.4 keV and 6.7 keV lines. Then the former EWs against the associated continuum in the bright clump regions are estimated to be 2.4_(-0.7)~(+2.3) keV. Since the two different approaches give similar large EWs of 2 keV, we strongly suggest that the 6.4 keV clumps in the Sgr C region are due to X-ray reflection/fluorescence (the X-ray reflection nebulae).