Active galactic nuclei at high redshifts: Properties and environment of Type 1 and 2 AGNs

Abstract

We explore host galaxy properties and environment of a sample of Type 1 and 2 active galactic nuclei (AGN) taken from the COSMOS2015 catalogue (Laigle et al.), within 0.3 ≤ z ≤ 1.1 selected for their emission in X-rays, optical spectra and SED signatures. We find different properties of host galaxies of distinct AGNs: Type 1 AGNs reside in blue, star-forming and less massive host galaxies compared to Type 2. The majority of the AGNs have intermediate X-ray luminosities, 1042 ≤ LX < 1044 erg s-1, while only a few have X-ray luminosities (LX > 1044 erg s-1) as those observed in QSOs. Non-parametric morphological analysis show that the majority of Type 1 AGN hosts are elliptical or compact galaxies, while Type 2 AGN host present more scatter, from spirals, irregulars, and elliptical galaxies. The environment of the differentAGNtypes are similar except at small scales (rp < 100 kpc),where Type 2AGNs have more neighbour galaxies than Type 1s. Galaxies located close to Type 2AGNs (~100 kpc) tend to have redder colours, and are more massive compared to the local environment of Type 1s. The observed differences in the environment and host galaxy properties of Type 1 and 2 AGN types show that the obscuration due to the presence of gas and dust may be distributed in larger galactic-scales, possibly originated by galaxy interactions or mergers., after COSMOS2015 catalogue.