ASTRO-H White Paper - Plasma Diagnostic and Dynamics of the Galactic Center Region

Understand

The most characteristic high-energy phenomena in the Galactic center (GC) region is the presence of strong K-shell emission lines from highly ionized Si, S, Ar, Ca, Fe and Ni, which form the Galactic Center X-ray Emission (GCXE).

• These multiple lines suggest that the GCXE is composed of at least two plasmas with temperatures of ~1 and ~7 keV.
• The GCXE also exhibits the K-shell lines from neutral Si, S, Ar, Ca, Fe and Ni atoms.
• A debatable issue is the origin of the GCXE plasma; whether it is a diffuse plasma or integrated emission of many unresolved point sources such as cataclysmic variables and active binaries.