Three Lyman-α Emitters at Z ≈ 6: Early Gmos/gemini Data from the Glare Project

We report spectroscopic detection of three z ∼ 6 Lyman-α emitting galaxies, in the vicinity of the Hubble Ultra Deep Field, from the early data of the Gemini Lyman-α at Reionisation Era (GLARE) project. Two objects, GLARE#3001 (z = 5.79) and GLARE#3011 (z = 5.94), are new detections and are fainter in z (z AB = 26.37 and 27.15) than any Lyman break galaxy previously detected in Lymanα. A third object, GLARE#1042 (z = 5.83) has previously been detected in line emission from the ground; we report here a new spectroscopic continuum detection. Gemini/GMOS-S spectra of these objects, obtained using nod & shuffle, are presented together with a discussion of their photometric properties. All three objects were selected for spectroscopy via the i-drop Lyman Break technique, the two new detections from the GOODS v1.0 imaging data. The red i−z colors and high equivalent widths of these objects suggest a high-confidence z > 5 Lyman-α identification of the emission lines. This brings the total number of known z > 5 galaxies within 9 of the Hubble Ultra Deep Field to four, of which three are at the same redshift (z = 5.8 within 2000 km s), suggesting the existence of a large-scale structure at this redshift. Subject headings: galaxies: evolution – galaxies: formation – galaxies: staburst – galaxies: individual: SBM03#1, SiD002 – galaxies: high redshift – ultraviolet: galaxies