Volume 428, Number 3, December IV 2004
|Page(s)||817 - 821|
|Section||Cosmology (including clusters of galaxies)|
|Published online||07 December 2004|
A search for clusters at high redshift
IV. Spectroscopy of Hα emitters in a proto-cluster at z = 2.16
Sterrewacht Leiden, PO Box 9513, 2300 RA, Leiden, The Netherlands e-mail: firstname.lastname@example.org
2 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
Accepted: 7 October 2004
Radio galaxy PKS 1138-262 is a massive galaxy at , located in a dense environment. We have found an overdensity of Lyα emitting galaxies in this field, consistent with a proto-cluster structure associated with the radio galaxy. Recently, we have discovered forty candidate Hα emitters by their excess near infrared narrow band flux. Here, we present infrared spectroscopy of nine of the brightest candidate Hα emitters. All these candidates show an emission line at the expected wavelength. The identification of three of these lines with Hα is confirmed by accompanying  emission. The spectra of the other candidates are consistent with Hα emission at , one being a QSO as indicated by the broadness of its emission line. The velocity dispersion of the emitters (360 km s-1) is significantly smaller than that of the narrow band filter used for their selection (1600 km s-1). We therefore conclude that the emitters are associated with the radio galaxy. The star formation rates (SFRs) deduced from the Hα flux are in the range 6-44 yr-1 and the SFR density observed is 5-10 times higher than in the HDF-N at . The properties of the narrow emission lines indicate that the emitters are powered by star formation and contain very young (<100 Myr) stellar populations with moderately high metallicities.
Key words: galaxies: active / galaxies: clusters: general / galaxies: evolution / cosmology: observations / cosmology: early Universe
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.