Study of a homogeneous X-ray selected AGN sample

Abstract

AbstractBased on optical identifications of ROSAT sources, we have created a large homogeneous catalog of X-ray selected AGN. The Hamburg-RASS Catalog (HRC) and Byurakan-Hamburg-RASS Catalog (BHRC) made up on the basis of optical identification of X-ray sources from ROSAT Bright Source (BSC) and Faint Source (FSC) catalogues, respectively, have been used. These identiifcations were based on low-dispersion spectra of Hamburg Quasar Survey (HQS). As a result, a new large sample of X-ray selected AGN has been compiled containing 4253 sources with photon count rate CR > 0.04 ct/s in the area with galactic latitudes |b|>20 and declinations δ>0. All these sources are classified as AGN or candidate AGN. We have carried out multiwavelength studies in several wavelength ranges (X-ray, optical, radio). Catalogues that more or less guarantee the completeness condition (all-sky or large area surveys) were used. A number of erroneous classifications were found (some AGN had been classified as stars or galaxies); 1024 and 59 from HRC and BHRC, respectively. Out of 4253 sources, 3352 are spectroscopically confirmed AGN (given in Veron-Cetty & Veron and Roma Blazar catalogs), and the rest 901 are candidate AGN. For 210 of them spectra are available in SDSS DR9, and the results of their classification are given in another paper. We calculated absolute magnitudes, fluxes, improved coordinates and redshifts. An attempt is made to find a connection between the radiation fluxes in different bands for different types of sources, and identify their typical characteristics, thus confirming candidate AGN and in some cases finding new ones.