New Active Galactic Nuclei Detected by the ART-XC and eROSITA Telescopes during the First Five SRG All-Sky X-ray Surveys. Part 2

Abstract

We present the results of our identification of 11 X-ray sources detected on the half of the sky $0^\circ<l<180^\circ$ in the 4-12 keV energy band on the combined map of the first five all-sky surveys with the Mikhail Pavlinsky ART-XC telescope onboard the SRG observatory. All these sources were also detected by the SRG/eROSITA telescope in the 0.2-8 keV energy band, whose data have allowed us to improve their positions and to investigate their X-ray spectra. Five of them have been detected in X-rays for the first time, while the remaining ones have already been known previously, but their nature has remained unknown. We have taken optical spectra for nine sources with the 1.6-m AZT-33IK telescope at the Sayan Observatory (the Institute of Solar-Terrestrial Physics, the Siberian Branch of the Russian Academy of Sciences); for two more objects we have analyzed the archival spectra from SDSS and the 6dF survey. The objects are classified as Seyfert galaxies (seven Sy1, three Sy1.9, and one Sy2) at redshifts $z$=0.029-0.258. Our analysis of the X-ray spectra has revealed a noticeable intrinsic absorption ($N_{\rm H} \sim 10^{22}$ cm$^{-2}$) in two of the four Seyfert 2 galaxies (Sy1.9-2). The spectrum of one more of them (SRGA J000132.9+240237) cannot be described within the model of an absorbed Comptonization continuum, which may point to a strong absorption and a significant contribution of the reflected radiation. However, the available SRG all-sky survey data are not enough to obtain reliable constraints on the absorption column density in this object, which is also interesting in that it is radio loud. Longer X-ray observations are required to refine the physical properties of this active galactic nucleus.