{
  "id": "1712.01872",
  "version": "v1",
  "published": "2017-12-05T19:07:49.000Z",
  "updated": "2017-12-05T19:07:49.000Z",
  "title": "XXL Survey XXI. The environment and clustering of X-ray AGN in the XXL-South field",
  "authors": [
    "O. Melnyk",
    "A. Elyiv",
    "V. Smolcic",
    "M. Plionis",
    "E. Koulouridis",
    "S. Fotopoulou",
    "L. Chiappetti",
    "C. Adami",
    "N. Baran",
    "A. Butler",
    "J. Delhaize",
    "I. Delvecchio",
    "F. Finet",
    "M. Huynh",
    "C. Lidman",
    "M. Pierre",
    "E. Pompei",
    "C. Vignali",
    "J. Surdej"
  ],
  "comment": "11 pages, 10 figures. Accepted for publication in A&A",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "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. 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. 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. 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.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-12-05T19:07:49.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray agn",
      "xxl survey xxi",
      "environment",
      "xxl-south field",
      "selected active galactic nuclei"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}