Program: GN-2009A-Q-9

We propose to obtain near-IR spectra of two members of a remarkable class of high-redshift quasars with extremely weak high-ionization emission lines in their UV spectra. Our team has been studying such sources extensively over the past decade, and we find that the weakness of the high-ionization lines is most likely due to extremely high accretion rates. Our proposed near-IR spectra will allow us to test this hypothesis directly by measuring the width of the H_beta emission line, which together with the continuum luminosity, allows a determination of the Eddington ratio. Our spectra will also provide measurements of the [O III] lines with implications for the narrow-line region in these sources. This pilot project will lead to the development of a larger program to determine black-hole masses and accretion rates for a representative sample of these sources. Ultimately, this study may lead to new insights about the accretion process and emission line formation in active galactic nuclei.