Volume 579, July 2015
|Number of page(s)||19|
|Section||Cosmology (including clusters of galaxies)|
|Published online||19 June 2015|
CLASH-VLT: Substructure in the galaxy cluster MACS J1206.2-0847 from kinematics of galaxy populations⋆,⋆⋆
1 Dipartimento di FisicaUniversità degli Studi di Trieste, via Tiepolo 11, 34143 Trieste, Italy
2 INAF/Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34133, Trieste, Italy
3 INAF/Osservatorio Astronomico di Capodimonte, via Moiariello 16 80131 Napoli, Italy
4 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
5 Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, via Saragat 1, 44122 Ferrara, Italy
6 Department of Astronomy, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile
7 INAF/IASF-Milano, via Bassini 15, 20133 Milano, Italy
8 Korea Institute for Advanced Study, KIAS, 85 Hoegiro, 130-722 Dongdaemun-gu Seoul, Republic of Korea
9 Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
10 INAF/Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
11 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
12 Observatories of the Carnegie Institution of Washington, Pasadena, CA 91 101, USA
13 Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milan, Italy
14 Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, 10617 Taipei, Taiwan
15 California Institute of Technology, MC 249-17, Pasadena, CA 91125, USA
16 Fundaciòn Galileo Galilei−INAF, Rambla José Ana Fernández Pérez 7, 38712 Breña Baja, La Palma, Spain
17 Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
18 Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
19 University of Vienna, Department of Astrophysics, Türkenschanzstr. 17, 1180 Wien, Austria
20 INAF/Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
21 INFN, Sezione di Bologna, via Ranzani 1, 40127 Bologna, Italy
22 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
23 University Observatory Munich, Scheinerstrasse 1, 81679 München, Germany
24 Max-Planck-Institut für extraterrestrische Physik, Posfatch 1312, Giessenbachstr., 85741 Garching, Germany
Received: 30 December 2014
Accepted: 16 March 2015
Aims. In the effort to understand the link between the structure of galaxy clusters and their galaxy populations, we focus on MACS J1206.2-0847 at z ~ 0.44 and probe its substructure in the projected phase space through the spectrophotometric properties of a large number of galaxies from the CLASH-VLT survey.
Methods. Our analysis is mainly based on an extensive spectroscopic dataset of 445 member galaxies, mostly acquired with VIMOS at VLT as part of our ESO Large Programme, sampling the cluster out to a radius ~2R200 (4 h70-1 Mpc). We classify 412 galaxies as passive, with strong Hδ absorption (red and blue galaxies), and with emission lines from weak to very strong. A number of tests for substructure detection are applied to analyze the galaxy distribution in the velocity space, in 2D space, and in 3D projected phase-space.
Results. Studied in its entirety, the cluster appears as a large-scale relaxed system with a few secondary, minor overdensities in 2D distribution. We detect no velocity gradients or evidence of deviations in local mean velocities. The main feature is the WNW-ESE elongation. The analysis of galaxy populations per spectral class highlights a more complex scenario. The passive galaxies and red strong Hδ galaxies trace the cluster center and the WNW-ESE elongated structure. The red strong Hδ galaxies also mark a secondary, dense peak ~2 h70-1 Mpcat ESE. The emission line galaxies cluster in several loose structures, mostly outside R200. Two of these structures are also detected through our 3D analysis. The observational scenario agrees with MACS J1206.2-0847 having WNW-ESE as the direction of the main cluster accretion, traced by passive galaxies and red strong Hδ galaxies. The red strong Hδ galaxies, interpreted as poststarburst galaxies, date a likely important event 1−2 Gyr before the epoch of observation. The emission line galaxies trace a secondary, ongoing infall where groups are accreted along several directions.
Key words: galaxies: clusters: individual: MACS J1206.2-0847 / galaxies: clusters: general / galaxies: kinematics and dynamics / galaxies: evolution / cosmology: observations
Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/579/A4
© ESO, 2015
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