CLASH-VLT: Substructure in the galaxy cluster MACS J1206.2-0847 from kinematics of galaxy populations

Autor(en)

M. Girardi, A Mercurio, I Balestra, Mario Nonino, Andrea Biviano, Oliver Czoske, Ulrike Kuchner, Christian Maier, Miguel Anibal Verdugo Olivares, Bodo Ziegler

Abstrakt

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.

Based in large part on data acquired at the ESO VLT (prog.ID 186.A-0798). Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via cdsarc.u-strasbg.fr/viz-bin/qcat

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Università degli Studi di Trieste, INAF Astronomical Observatory of Triest, INAF-Osservatorio Astronomico di Capodimonte

Journal

Astronomy & Astrophysics

Band

579

Anzahl der Seiten

19

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/201425599

Publikationsdatum

07-2015

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/clashvlt-substructure-in-the-galaxy-cluster-macs-j120620847-from-kinematics-of-galaxy-populations(9caa14b0-b6b0-4492-9b45-f3c72f6dee09).html