The Number Density of Intermediate‐ and High‐Luminosity Active Galactic Nuclei atz∼ 2–3

We use the combination of the 2 Ms Chandra X-ray image, new J and H bandimages, and the Spitzer IRAC and MIPS images of the Chandra Deep Field-North toobtain high spectroscopic and photometric redshift completeness of high andintermediate X-ray luminosity sources in the redshift interval z=2-3. Wemeasure the number densities of z=2-3 active galactic nuclei (AGNs) andbroad-line AGNs in the rest-frame 2-8 keV luminosity intervals 10^44-10^45 and10^43-10^44 ergs/s and compare with previous lower redshift results. We confirma decline in the number densities of intermediate-luminosity sources at z>1. Wealso measure the number density of z=2-3 AGNs in the luminosity interval10^43-10^44.5 ergs/s and compare with previous low and high-redshift results.Again, we find a decline in the number densities at z>1. In both cases, we canrule out the hypothesis that the number densities remain flat to z=2-3 at abovethe 5-sigma level.Comment: 8 pages, Accepted by The Astrophysical Journal (scheduled for 10 Dec 2005