Program: GN-2015A-Q-28

We propose to take GNIRS spectroscopy of 11 more newly discovered Pan-STARRS1 z 6 quasars. Luminous quasars at high redshift provide direct probes of the evolution of supermassive black holes and the intergalactic medium at early cosmic time. Over the last decade, the Sloan Digital Sky Survey (SDSS) established a sample of ∼19 very bright quasars at 5.7 < z < 6.5 (e.g. Fan et al. 2003, AJ 125, 1649, Fan et al. 2004, AJ 128, 515, Fan et al. 2006, AJ 132, 117). Detailed studies of these distant quasars have revolutionised our understanding of the young universe. However, recently a handful of low luminosity quasars at z ∼ 6, have been found. These objects are powered by black holes of a few×108Msun (De Rosa et al. 2011, ApJ 739, 56, Kurk et al. 2009, ApJ 702, L833). These are an order of magnitude less massive than typical z ∼ 6 SDSS quasars. While the black hole masses are more similar to those powering quasars at lower redshifts, the distribution of Eddington ratios is strikingly different from what is observed in low redshift quasars. This may indicate that quasars with similar luminosities to normal quasars at z ∼ 2 are nonetheless somehow quite different from normal quasars. A larger sample of low luminosity quasars at z ∼ 6 with high quality infrared spectroscopy is required to test the claims of Kurk et al. 2009, and De Rosa et al. 2011.