Integral ibis extragalactic survey: Active galactic nuclei selected at 20-100 keV

Analysis of International Gamma-Ray Astrophysics Laboratory (INTEGRAL) Core Programme and public open-time observations performed up to 2005 April provides a sample of 62 active galactic nuclei in the 20-100 keV band above a flux limit of ~1.5 × 10-11 ergs cm-2 s-1. Most (42) of the sources in the sample are Seyfert galaxies, almost equally divided between type 1 and type 2 objects; six are blazars, and 14 are still unclassified. Excluding the blazars, the average redshift of our sample is 0.021, while the mean luminosity is log L = 43.45. We find that absorption is present in 65% of the objects, with 14% of the total sample due to Compton-thick active galaxies. In agreement with both Swift BAT team results and 2-10 keV studies, the fraction of absorbed objects decreases with the 20-100 keV luminosity. All Seyfert 2's in our sample are absorbed, as are 33% of Seyfert 1's. The present data highlight the capability of INTEGRAL to probe the extragalactic gamma-ray sky and to find new and/or absorbed active galaxies