Dust from early galaxies and the X-ray background radiation

We explore the effects of the scattering of cosmic X-ray background photons by dusty foreground galaxies, assuming the X-rays themselves arise in discrete sources. The effective angle of scattering is ∼1-10 arcmin in the 1-3 keV band, which can lead to a decrease in the spatial fluctuations of the background observed with an IPC-like imaging device with ∼1 arcmin resolution. This can reduce the number of discrete sources required to explain the smoothness of the background to values greater than ∼10³ deg^-2. The effect may be stronger in the direction of distant clusters of galaxies, or if distant galaxies are much dustier than assumed here.