X-Ray Emission from the Galactic Disk

A search was made for a diffuse component of X-rays > 1.5 keV associated with an interarm region of the Galaxy at galactic longitudes in the vicinity of 6O . A statistically significant excess associated with a narrow disk component was detected. The angular extent of this component has a most probable value of 2 and may be as large as 7 at 90 percent confidence. The best-fit spectrum yields an intensity of 2.9 photons s ' over the 2-10-keV range. The 3 upper lirnit to any emission (e.g., iron line) in a 1.5-keV band centered at 7 keV from galactic latitudes b < 3.5 degrees is 0.3 photons s- . Several possible emission models are evaluated, with the most likely candidate being a population of unresolvable low-luminosity discrete sources.