(Proposal ID) S11A-125

(PI) Morihana, Kumiko

(Proposal Title)
K-band Spectroscopy of Dim X-ray Sources in the Galactic Plane

(Abstract)
The Galactic ridge X-ray emission (GRXE) is one of the remaining mysteries of 
the X-ray astronomy. The GRXE is an apparently diffuse emission in low surface 
brightness, which extends along the inner part of the Galactic Plane. Both 
thermal and non-thermal features are found in the spectrum. It is controversial
 whether the GRXE can be explained only by unresolved point sources or truly 
diffuse component exists. Classifying the nature of individual dim X-ray point 
sources and revealing the typical X-ray source population is obviously a key. 
Our recent Suzaku result suggests a difference in the X-ray population or 
thermal/non-thermal contrast along the Galactic latitude. In this program, we 
aim to obtain X-ray point source population at b = -1.deg4 and compares it with
 our previous result obtained at b =0.deg0. We take the source classification 
method established at b =0.deg0, in which we use H, He, and metallic emission/
absorption features in the K-band spectra of ~100 X-ray sources using MOIRCS.