Abstract

We report the spectroscopic confirmation of a compact Ly? emitting galaxy at z = 5.721. A FORS2 spectrum of the source shows a strong asymmetric line with a flux of 5 × 10 -17 erg s -1 cm -2, making it one of the brightest Ly? emitting galaxies at this redshift, and a line-of-sight velocity dispersion of 400 km s -1. We also have a tentative detection of a second, narrower component that is redshifted by 400 km s -1 with respect to the main peak. A FORS2 image shows that the source is compact, with a FWHM of 0?.75, which corresponds to 3.2 kpc at this redshift**. This source is a brighter example of J1236.8+6215 (Dawson et al. 2002, ApJ, 570, 92), another Lya emitting galaxy at z ? 5.2.