A Galaxy at [ITAL]z[/ITAL] = 5.34

Abstract

We report the discovery of Lyα emission from a galaxy at z=5.34, the first object at z>5 with a spectroscopically confirmed redshift. The faint continuum emission [m_AB(8000 Å) ≈ 27], the relatively small rest-frame equivalent width of the emission line (W^rest_Lyα ≈ 95 Å), and the limits on the N V/Lyα ratio suggest that this is a star-forming galaxy and not an active galactic nucleus. The star formation rates implied by the UV continuum emission and the Lyα emission are (in the absence of dust extinction) fairly modest (~6 h⁻²₅₀ M_☉ yr^-1 for q₀=0.5). The continuum luminosity is similar to that of sub-L^*₁₅₀₀ star-forming galaxies at z~3, and the width of the Lyα line yields an upper limit to the mass of less than 2.6×10¹⁰ M_☉. The strong emission line detected in this low-luminosity galaxy provides hope for the discovery of higher luminosity primeval galaxies at redshifts z>5.