Large-scale structure of Lyman break galaxies around a radio galaxy protocluster at z

¹ Sterrewacht Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands e-mail: intema@strw.leidenuniv.nl
² INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁴ Hubble Fellow
⁵ National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
⁶ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany

Received: 5 January 2006
Accepted: 7 June 2006

Abstract

We present broad-band imaging with the Subaru Telescope of a    field surrounding the radio galaxy TN J1338–1942 at redshift . The field contains excesses of Lyman-α emitters (LAEs) and Lyman break galaxies (LBGs) identified with a protocluster surrounding the radio galaxy. Our new wide-field images provide information about the boundary of the protocluster and its surroundings. There are 874 candidate LBGs within our field, having redshifts in the range . An examination of the brightest of these (with ) shows that the most prominent concentration coincides with the previously discovered protocluster. The diameter of this galaxy overdensity corresponds to ~2 Mpc at , consistent with the previous estimation using LAEs. Several other concentrations of LBGs are observed in the field, some of which may well be physically connected with the  protocluster. The observed structure in the smoothed LBG distribution can be explained as the projection of large-scale structure, within the redshift range , comprising compact overdensities and prominent larger voids. If the observed compact overdensities are associated with protoclusters, the observed protocluster volume density is ~5  10^-6 Mpc^-3, similar to the volume density of rich clusters in the local Universe.