``Evidence for the Galactic X-ray Bulge II''

Sangwook Park and John P. Finley

Department of Physics, Purdue University
1396 Physics Building, West Lafayette, IN. 47907

and

T. M. Dame

Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Cambridge, MA. 02138

Accepted for the publication in the Astrophysical Journal, 1998


Abstract
A mosaic of 5 ROSAT PSPC pointed observations in the Galactic plane (l ~ 25 deg) reveals X-ray shadows in the 0.5-2.0 keV band cast by distant molecular clouds. The observed on-cloud and off-cloud X-ray fluxes indicate that ~15% and ~37% of the diffuse X-ray background in this direction in the 0.75 keV and 1.5 keV band, respectively, originates behind the molecular gas which is located at ~3 kpc from the Sun. The implication of the derived background X-ray flux beyond the absorbing molecular cloud is consistent with and lends further support to recent observations of a Galactic X-ray bulge.