Discovery of a new high redshift QSO at z=5.96 with the Subaru telescope

We report a discovery of a new high redshift quasar at z = 5.96, observed with the FOCAS long-slit spectrograph on board the Subaru telescope. The spectrum shows strong and broad Lyα+NV emission lines with a sharp discontinuity to the blue side. A Lyβ+OVI emission line is also detected, providing a consistent redshift measurement with the Lyα+NV emission. The QSO has an absolute magnitude of MAB,1450 = −26.9 (H0 = 50km s Mpc, q0 = 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 to 5.82, along the line of sight to this z = 5.96 QSO. Therefore the Universe was already highly ionized at z = 5.82.