Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published June 2010 | Published
Journal Article Open

Spectroscopic confirmation of a galaxy cluster associated with 7C 1756+6520 at z = 1.416


We present spectroscopic follow-up of an overdensity of galaxies photometrically selected to be at 1.4 < z < 2.5 found in the vicinity of the radio galaxy 7C 1756+6520 at z = 1.4156. Using the DEIMOS optical multi-object spectrograph on the Keck 2 telescope, we observed a total of 129 BzK-selected sources, comprising 82 blue, star-forming galaxy candidates (sBzK) and 47 red, passively-evolving galaxy candidates (pBzK^*), as well as 11 mid-infrared selected AGN candidates. We obtain robust spectroscopic redshifts for 36 blue galaxies, 7 red galaxies and 9 AGN candidates. Assuming all foreground interlopers were identified, we find that only 16% (9%) of the sBzK (pBzK^*) galaxies are at z < 1.4. Therefore, the BzK criteria are shown to be relatively robust at identifying galaxies at moderate redshifts. Twenty-one galaxies, including the radio galaxy, four additional AGN candidates and three red galaxy candidates are found with 1.4156 ± 0.025, forming a large scale structure at the redshift of the radio galaxy. Of these, eight have projected offsets <2 Mpc relative to the radio galaxy position and have velocity offsets <1000 km s^(-1) relative to the radio galaxy redshift. This confirms that 7C 1756+6520 is associated with a high-redshift galaxy cluster. A second compact group of four galaxies is found at z ~ 1.437, forming a sub-group offset by Δv ~ 3000 km s^(-1) and approximately 1.'5 east of the radio galaxy.

Additional Information

© ESO 2010. Received 4 March 2009. Accepted 17 April 2010. Published online 21 July 2010. This work is based on a spectroscopic campaign at the W. M. Keck Observatory, a scientific partnership between the University of California and the California Institute of Technology, made possible by a generous gift of the W. M. Keck Foundation. We are very grateful to Tadayuki Kodama for having provided the models of red sequence presented in this paper. We thank the anonymous referee for his/her careful reading of the manuscript and constructive comments. The work of DS and RLG was carried out at Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. S.A.S.'s work was performed under the auspices of the US Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Attached Files

Published - Galametz2010p11062Astron_Astrophys.pdf


Files (1.6 MB)
Name Size Download all
1.6 MB Preview Download

Additional details

August 22, 2023
October 20, 2023