Iron Emission Lines on the Galactic Ridge Observed with Suzaku
Koyama, Katsuji; Ezoe, Yuichiro; Yamasaki, Noriko Y.; Ebisawa, Ken; Matsumoto, Hironori; Takahashi, Hiromitsu; Tanaka, Yasuo; Yamauchi, Shigeo
Japan, Germany
Abstract
In order to elucidate the origin of galactic ridge X-ray emission, we analyzed Suzaku data taken at various regions along the galactic plane, and studied their Fe-K emission line features. Suzaku resolved the Fe line complex into three narrow lines at ∼6.4keV, ∼6.7keV and ∼6.97keV, which are K-lines from neutral (or low-ionized), He-like, and H-like iron respectively. The 6.7keV line is clearly seen in all of the observed regions, and its longitudinal distribution is consistent with that determined from previous observations. The 6.4keV emission line was also found in various galactic plane regions (b∼0°). Differences in the flux ratios of the 6.4keV/6.7keV and 6.97keV/6.7keV lines between the galactic plane and the galactic center regions were studied and its implication was discussed.