The AGN source population in the Chandra Deep Field‐North Survey: constraints from X‐ray spectroscopy and variability

We briefly report here on our ongoing X-ray spectroscopy and variabilityanalyses of 136 faint X-ray sources discovered in the 2 Ms Chandra Deep FieldNorth observations spanning 1.4x10-15 to 2x10-13 ergs s-1 cm-2. Most sourcesare adequatley fitted with a simple intrinsic absorption plus power-law model,although the resulting photon index is much lower than the canonical averageunabsorbed spectral slope found locally (suggesting additional spectralcomplexity). Among the 136 sources, 7% show significant Fe (Ka) emissionfeatures, with equivalent widths in the range 0.1-1.3 keV. Two of theseemission-line sources appear to be Compton thick. For the subset of sourceswith redshifts, we also find that fewer than 10% are likely to be Comptonthick. Finally, ~60% of the sample show signs of long-term variability. Thisfraction climbs to ~90% for the bright sources (>500 cnts) or BLAGN.Comment: Proceedings for the "X-ray Surveys: in the light of new observatories" workshop (submitted to Astron. Nachrichten; includes anabs.cls style file). One page and two figure