Program: GS-2006A-Q-22

We propose to use GNIRS on Gemini-South to carry out a near-IR spectroscopic survey of a sample of five luminous quasars at $z\sim 6.0$. The proposed observations, covering 0.9 to 2.5$\mu$m in the observed frame, will measure the rest-frame UV spectroscopic properties of highest-redshift quasars. All survey targets have extensive follow-up observations in X-ray, Spitzer bands, sub-millimeter, and radio wavelengths, providing a fundamental dataset to study the evolution of luminous quasars at high redshift in the context of the growth of early supermassive black holes and their relation to galaxy formation. The new IR data will provide the crucial missing link in the spectral energy distributions of high-redshift quasars. The spectra will be used to directly measure the metal abundance in the quasar environment, to estimate the central black hole mass, and combined with observations in other wavelengths, to study the evolution of emission and absorption mechanisms at the highest redshift. In addition, these spectra will be used to study the evolution of intergalactic MgII absorption at $z=2.5 - 6$.