Isolating the Foreground of the X-Ray Background

Abstract

The foreground component of the X-ray Background (XRB) can be studied by cross-correlating its intensity with galaxy catalogs. We computed the two-point cross-correlation function $W_{xg}$ between 67 {\em Einstein} X-ray fields and the APM galaxy catalog. We detected a signal with an amplitude of $W_{xg}=.04\pm .01$, significant at the $3.5\sigma$ level. The reality of this signal was tested with a series of control data sets. We discuss how this signal can be used to constrain models of the XRB.

To appear in Proc. of "Roentgenstrahlung from the Universe" held in Wuerzburg, Germany, in Sept. 1995. 2 pages, 2 figures included, uuencoded compressed Postscript