Spectral Properties of Heavily Obscured Seyfert Galaxies from the INTEGRAL All-Sky Survey

We have investigated the X-ray spectral properties of the ten heavily obscured nearby (z < 0.1) active galactic nuclei (AGNs) IGR J00256+6821, NGC 1194, CGCG 420−015, IGR J09253+6929, NGC 3281, NGC 4939, IGR J14175−4641, NGC 5643, NGC 5728, and ESO 137−G034 from the catalogue of hard X-ray sources detected during the INTEGRAL seven-year all-sky survey. Based on data from the NuSTAR space telescope supplemented with XMM-Newton and Chandra data at low energies, we have estimated the intrinsic absorption column densities, photon indices, and intrinsic luminosities of these AGNs. In three objects (NGC 5643, NGC 3281, and ESO 137−G034) the absorption column density (NH) exceeds 2 × 1024 cm−2, while the observed spectrum is dominated by the emission from the central source scattered in the surrounding gas-dust torus. In five objects (IGR J00256+6821, IGR J14175−4641, CGCG 420−015, NGC 1194, and NGC 5728) NH = 1−2 × 1024 cm−2, while the emissions transmitted through the torus and reflected from it make comparable contributions to the recorded X-ray flux. Two more sources (IGR J09253+6929 and NGC 4939) manifested themselves as Compton-thin (NH < 5 × 1023 cm−2) AGNs during the NuSTAR observations. The intrinsic luminosities of the investigated AGNs exceed the observed ones by up to a factor of 7. Given the results obtained now for almost the entire sample of AGNs from the catalogue of the INTEGRAL seven-year all-sky survey, there are reliable absorption column density and intrinsic luminosity estimates, which make it one of the best samples for investigating the population of AGNs in the local Universe.