Melnyk, O.O.MelnykElyiv, A.A.ElyivSmolčić, V.V.SmolčićPlionis, M.M.PlionisKoulouridis, E.E.KoulouridisFotopoulou, S.S.FotopoulouCHIAPPETTI, LUCIOLUCIOCHIAPPETTIAdami, C.C.AdamiBaran, N.N.BaranButler, A.A.ButlerDelhaize, J.J.DelhaizeDelvecchio, I.I.DelvecchioFinet, F.F.FinetHuynh, M.M.HuynhLidman, C.C.LidmanPierre, M.M.PierrePompei, E.E.PompeiVignali, C.C.VignaliSurdej, J.J.Surdej2020-10-052020-10-0520180004-6361http://hdl.handle.net/20.500.12386/27584Context. This work is part of a series of studies focusing on the environment and the properties of the X-ray selected active galactic nuclei (AGN) population from the XXL survey. The present survey, given its large area, continuity, extensive multiwavelength coverage, and large-scale structure information, is ideal for this kind of study. Here, we focus on the XXL-South (XXL-S) field. <BR /> Aims: Our main aim is to study the environment of the various types of X-ray selected AGN and investigate its possible role in AGN triggering and evolution. <BR /> Methods: We studied the large-scale (>1 Mpc) environment up to redshift z = 1 using the nearest neighbour distance method to compare various pairs of AGN types. We also investigated the small-scale environment (<0.4 Mpc) by calculating the local overdensities of optical galaxies. In addition, we built a catalogue of AGN concentrations with two or more members using the hierarchical clustering method and we correlated them with the X-ray galaxy clusters detected in the XXL survey. <BR /> Results: It is found that radio detected X-ray sources are more obscured than non-radio ones, though not all radio sources are obscured AGN. We did not find any significant differences in the large-scale clustering between luminous and faint X-ray AGN, or between obscured and unobscured ones, or between radio and non-radio sources. At local scales (<0.4 Mpc), AGN typically reside in overdense regions, compared to non-AGN; however, no differences were found between the various types of AGN. A majority of AGN concentrations with two or more members are found in the neighbourhood of X-ray galaxy clusters within <25-45 Mpc. Our results suggest that X-ray AGN are typically located in supercluster filaments, but they are also found in over- and underdense regions.STAMPAenArticle10.1051/0004-6361/2017304792-s2.0-85057265975000450930100006https://www.aanda.org/articles/aa/full_html/2018/12/aa30479-17/aa30479-17.htmlhttps://arxiv.org/abs/1712.018722018A&A...620A...6MFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation