Abstract
We report the discovery of a new high-redshift quasar at z = 5.96, observed with the long-slit Faint Object Camera and Spectrograph on board the Subaru Telescope. The spectrum shows strong and broad Lyα + N V emission lines with a sharp discontinuity to the blue side. ALyβ + O VI emission line is also detected, providing a consistent redshift measurement with the Lyα + N V emission. The quasi-stellar object (QSO) has an absolute magnitude of M AB,1450 = -26.9 (H 0 = 50 km s -1 Mpc -1 , q 0 = 0.5). The spectrum shows significant flux in the region 8000-8300 Å and thus does not show a complete Gunn-Peterson trough in the redshift range 5.58-5.82, along the line of sight to this z = 5.96 QSO. Therefore, the Universe was already highly ionized at z = 5.82. © 2006 RAS.