Discoveries of Diffuse Iron Line Sources from the Sgr B Region

Abstract

Abstract The radio complex Sgr B region was observed with the X-ray Imaging Spectrometer (XIS) on board Suzaku. This region exhibits diffuse iron lines at 6.4, 6.7, and 6.9 keV, which are $\mathrm{K}\alpha$ lines of Fe I (neutral iron), Fe XXV (He-like iron), and Fe XXVI (H-like iron), respectively. The high energy resolving power of the XIS provided separate maps of the K-shell transition lines from Fe I (6.4 keV) and Fe XXV (6.7 keV). Although the 6.7 keV line is smoothly distributed over the Sgr B region, a local excess is found near $(l, b) = ({0\rlap {.}{}^{\mathrm {\circ }}61}, {0\rlap {.}{}^{\mathrm {\circ }}01})$, possibly due to a new SNR. The plasma temperature is $kT\sim 3 \,\mathrm{keV}$ and the age is estimated to be younger than $7 \times 10^{3} \,\mathrm{yr}$. The 6.4 keV image is clumpy with local excesses near Sgr B2 and at $(l, b) = ({0\rlap {.}{}^{\mathrm {\circ }}74},- {0\rlap {.}{}^{\mathrm {\circ }}09})$. Like Sgr B2, this excess may be another candidate of an X-ray reflection nebula.