Reference : The XXL Survey: XII. Optical spectroscopy of X-ray-selected clusters and the frequenc...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/218148
The XXL Survey: XII. Optical spectroscopy of X-ray-selected clusters and the frequency of AGN in superclusters
English
Koulouridis, E. [Service d'Astrophysique AIM, DSM/IRFU/SAp, CEA Saclay, Gif-sur-Yvette, France, Institute for Astronomy and Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Palaia Penteli, Athens, Greece]
Poggianti, B. [INAF-Astronomical Observatory of Padova, Vicolo Osservatorio 5, Padova, Italy]
Altieri, B. [European Space Astronomy Centre (ESA/ESAC), Operations Department, Villanueva de la Canãda, Madrid, Spain]
Valtchanov, I. [European Space Astronomy Centre (ESA/ESAC), Operations Department, Villanueva de la Canãda, Madrid, Spain]
Jaffé, Y. [Department of Astronomy, Universidad de Concepción, Casilla 160-C, Concepción, Chile]
Adami, C. [LAM, OAMP, Université Aix-Marseille, CNRS, Pôle de l'Étoile, Site de Chãteau Gombert, 38 rue Frédéric Joliot-Curie, Marseille 13 Cedex, France]
Elyiv, A. [Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, Bologna, Italy, Main Astronomical Observatory, Academy of Sciences of Ukraine, 27 Akademika Zabolotnoho St., Kyiv, Ukraine]
Melnyk, O. [Department of Physics, University of Zagreb, Bijenicka cesta 32, Zagreb, Croatia, Astronomical Observatory, Taras Shevchenko National University of Kyiv, 3 Observatorna St., Kyiv, Ukraine]
Fotopoulou, S. [Department of Astronomy, University of Geneva, Chemin d'Écogia 16, Versoix, Switzerland]
Gastaldello, F. [INAF-IASF-Milano, via Bassini 15, Milano, Italy]
Horellou, C. [Dept. of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden]
Pierre, M. [Service d’Astrophysique AIM, DSM / IRFU / SAp, CEA Saclay, F-91191 Gif sur Yvette, France > > > >]
Pacaud, F. [Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, Bonn, Germany]
Plionis, M. [Institute for Astronomy and Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Palaia Penteli, Athens, Greece, Physics Department of Aristotle University of Thessaloniki, University Campus, Thessaloniki, Greece, Instituto Nacional de Astrofísica Optica y Electrónica, Puebla, CP, Mexico]
Sadibekova, T. [Service d'Astrophysique AIM, DSM/IRFU/SAp, CEA Saclay, Gif-sur-Yvette, France]
Surdej, Jean mailto [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO) >]
2016
Astronomy and Astrophysics
EDP Sciences
592
Yes (verified by ORBi)
International
0004-6361
1432-0746
[en] Galaxies: active ; Galaxies: clusters: general ; Galaxies: evolution ; Galaxies: interactions ; Large-scale structure of Universe ; X-rays: galaxies: clusters ; Spectroscopic analysis ; Surveys ; Galaxies : active ; Galaxies: clusters: General ; Galaxies: evolutions ; Large scale structure of universe ; X rays: galaxies: clusters ; Galaxies
[en] Context. This article belongs to the first series of XXL publications. It presents multifibre spectroscopic observations of three 0.55 deg2 fields in the XXL Survey, which were selected on the basis of their high density of X-ray-detected clusters. The observations were obtained with the AutoFib2+WYFFOS (AF2) wide-field fibre spectrograph mounted on the 4.2 m William Herschel Telescope. Aims. The paper first describes the scientific rationale, the preparation, the data reduction, and the results of the observations, and then presents a study of active galactic nuclei (AGN) within three superclusters. Methods. To determine the redshift of galaxy clusters and AGN, we assign high priority to a) the brightest cluster galaxies (BCGs), b) the most probable cluster galaxy candidates, and c) the optical counterparts of X-ray point-like sources. We use the outcome of the observations to study the projected (2D) and the spatial (3D) overdensity of AGN in three superclusters. Results. We obtained redshifts for 455 galaxies in total, 56 of which are counterparts of X-ray point-like sources. We were able to determine the redshift of the merging supercluster XLSSC-e, which consists of six individual clusters at z ~ 0.43, and we confirmed the redshift of supercluster XLSSC-d at z ~ 0.3. More importantly, we discovered a new supercluster, XLSSC-f, that comprises three galaxy clusters also at z ~ 0.3. We find a significant 2D overdensity of X-ray point-like sources only around the supercluster XLSSC-f. This result is also supported by the spatial (3D) analysis of XLSSC-f, where we find four AGN with compatible spectroscopic redshifts and possibly one more with compatible photometric redshift. In addition, we find two AGN (3D analysis) at the redshift of XLSSC-e, but no AGN in XLSSC-d. Comparing these findings with the optical galaxy overdensity we conclude that the total number of AGN in the area of the three superclusters significantly exceeds the field expectations. All of the AGN found have luminosities below 7 × 1042 erg s-1. Conclusions. The difference in the AGN frequency between the three superclusters cannot be explained by the present study because of small number statistics. Further analysis of a larger number of superclusters within the 50 deg2 of the XXL is needed before any conclusions on the effect of the supercluster environment on AGN can be reached. © ESO, 2016.
3130476, FONDECYT, Fondo Nacional de Desarrollo Científico y Tecnológico; RE 1462-6, DFG, Massachusetts Department of Fish and Game; NASA, National Aeronautics and Space Administration
Researchers ; Professionals
http://hdl.handle.net/2268/218148
10.1051/0004-6361/201526976

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