Redshift–luminosity characterization of active galactic nucleus galaxies having obscuring dusty material using the spectral energy distribution from the X-ray to far-infrared

Abstract

ABSTRACT The spectral energy distribution (SED) from the X-ray to far-IR is used to characterize active galactic nuclei (AGNs) having obscuring dusty material. A sample of 73 AGNs, with redshifts of z < 2.5, is subdivided based on the optical spectra into subgroups of type 1 and 2 AGNs and no-AGN. The x-cigale code is used to produce the SEDs of these galaxies, fitting them with their observed flux densities. Accordingly, this code provides estimates of the physical properties, including the stellar mass, dust-to-gas mass ratio, far-UV attenuation, star-formation rate, and luminosity. All these properties and luminosity components, namely stellar, AGN, X-ray, and dust luminosities, are characterized versus the redshift. With the caveat that the sample is flux-limited and thus is affected by Malmquist bias, the results show that these properties increase as a function of redshift with various variation rates for each galaxy group, except for the far-UV attenuation of type 1 AGNs, which shows a slight reduction with redshift. The stellar, AGN, and X-ray luminosities show tight correlations with the intrinsic AGN luminosity, which is, in principle, attributed to the intrinsic AGN accretion power acting as a fuelling source. This power has an impact on most other correlations versus the redshift when the intrinsic AGN luminosity increases with redshift. Owing to their different emission sources, these luminosities make different fractional contributions to the total luminosity. The stellar luminosity, where the dust luminosity is the most effective, has the highest contribution of all galaxy groups, while the AGN luminosity has the lowest.