MAGNETICALLY CONFINED INTERSTELLAR HOT PLASMA IN THE NUCLEAR BULGE OF OUR GALAXY

The origin of the Galactic center diffuse X-ray emission (GCDX) is still under intense investigation. In particular, the interpretation of the hot (kT approximate to 7 keV) component of the GCDX, characterized by the strong Fe 6.7 keV line emission, has been contentious. If the hot component originates from a truly diffuse interstellar plasma, not a collection of unresolved point sources, such plasma cannot be gravitationally bound, and its regeneration would require a huge amount of energy. Here, we show that the spatial distribution of the GCDX does not correlate with the number density distribution of an old stellar population traced by near-infrared light, strongly suggesting a significant contribution of the diffuse interstellar plasma. Contributions of the old stellar population to the GCDX are implied to be similar to 50% and similar to 20% in the nuclear stellar disk (NSD) and nuclear star cluster, respectively. For the NSD, a scale height of 0 degrees.32 +/- 0 degrees.02 is obtained for the first time from the stellar number density profiles. We also show the results of the extended near-infrared polarimetric observations in the central 3 degrees x 2 degrees region of our Galaxy, and confirm that the GCDX region is permeated by a large scale, toroidal magnetic field (MF) as previously claimed. Together with observed MF strengths close to energy equipartition, the hot plasma could be magnetically confined, reducing the amount of energy required to sustain it.