We present the discovery of five new quasars at z > 5.7, selected from the multicolor imaging data of the Sloan Digital Sky Survey (SDSS). Three of them, at redshifts 5.93, 1 Based on observations obtained with the Sloan Digital Sky Survey, and with the Apache Point Observatory 3.5-meter telescope, which is owned and operated by the Astrophysical Research Consortium; and with the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution, with the Univeristy of Arizona 2.3-meter Bok Telescope, with the Kitt Peak National Observatory 4-meter Mayall Telescope, with the 6.5-meter Landon Clay Telescope at the Las Campanas Observatory, a collaboration between the Observatories of the

We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent tail of the Lyα + N v equivalent width distribution, and we compare them to quasars with more typical emission-line properties and to low-redshift active galactic nuclei with weak/absent emission lines, namely BL Lac objects. We find that WLQs exhibit hot (T ∼ 1000 K) thermal dust emission and have rest-frame 0.1-5 μm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most probable scenario for WLQs involves broad-line region properties that are physically distinct from those of normal quasars.

We present the discovery of seven quasars at z > 5:7, selected from $2000 deg 2 of multicolor imaging data of the Sloan Digital Sky Survey. The new quasars have redshifts z from 5.79 to 6.13. Five are selected as part of a complete flux-limited sample in the SDSS northern Galactic cap; two have larger photometric errors and are not part of the complete sample. One of the new quasars, SDSS J1335+3533 (z ¼ 5:93), exhibits no emission lines; the 3 limit on the rest-frame equivalent width of the Ly+N v line is 5 8. It is the highest redshift lineless quasar known and could be a gravitational lensed galaxy, a BL Lac object, or a new type of quasar. Two new z > 6 quasars, SDSS1250+3130 (z ¼ 6:13) and SDSS J1137+3549 (z ¼ 6:01), show deep Gunn-Peterson absorption gaps in Ly. These gaps are narrower than the complete Gunn-Peterson absorption troughs observed among quasars at z > 6:2 and do not have complete Ly absorption.