Data Centre for Astrophysics
Astronomy Department of the University of Geneva
ISDC Seminar

Thursday, February 28, 2002 at 11:00

Ken Ebisawa

Chandra Deep X-ray Observation of the Galactic Plane

Abstract. Using the Chandra X-ray satellite, we have carried out the deepest X-ray observation on a typical Galactic plane region. Our main motivations were

  1. to examine if the Galactic plane hard X-ray emission is truly diffuse emission or composed of numerous point sources, and
  2. to investigate the nature of the dimmest X-ray sources on the Galactic plane.
We have detected more than 270 new X-ray sources in the two Chandra mosaic fields (~25'x25'). There seems to be two populations of sources, soft spectral sources which are bright only below 2 keV, and hard ones which are conspicuous above 2 keV. In the hard X-ray band (2-10 keV), we found the point source X-ray flux account for only ~10 % of the total energy flux observed in the field of view, that indicates that the Galactic hard X-ray emission has truly diffuse nature. We also found the surface density of the hard X-ray sources is comparable to that in high Galactic regions, which strongly suggest most of the hard X-ray sources we detected are extragalactic AGNs seen through the Galactic plane.

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