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G. Garmire (Penn State University), ACIS CDF-N Team
The Chandra X-ray Observatory has completed two 1 Ms exposures to the X-ray sky. These very deep exposures have detected over 700 X-ray sources, most of which appear to be AGN and QSOs. The mean X-ray luminosity of the sources rises rapidly from the local value to a maximum at a redshift of 3 and then appears to fall off. The average volume emissivity of sources also rises rapidly to a redshift of 1 and then drops more rapidly up to the highest redshift detected of 5.18. A comparison of the density of X-ray sources on the sky shows a variation of the order of 40 fields that have been examined, indicating considerable cosmic variance on scales of 100 sq. arc minutes. Power law fits to the spectra of the brighter sources reveals a photon index that decreases with decreasing source intensity. The summed intensity of the observed sources in the 1.0 - 8.0 keV band is greater than 80 "diffuse" X-ray background, with a photon index that agrees with the "diffuse" measurements.
This work was suported by NASA grant NAS 8-38252.