Finding protoquasars at high resdshifts

Phenomenological and theoretical arguments suggest that the progenitors of quasars form at high redshifts (z≥10). Searches for protoquasars may best be undertaken in the infrared or millimeter regimes; optical surveys are limited by intrinsic dust extinction or intergalactic absorption. Under plausible conditions, the emission of fine-structure lines from the host systems of quasars can be detected by millimeter telescopes. For example, the [C II] 158 μm line flux from a bulge surrounding a bright quasar at a redshift of 10 can reach a value ∼2 mJy. This signal will be detectable at the 3 σ level with a 1″ beam and a velocity resolution of 150 km s −1 after 40 minutes of observation by the future Millimeter Array telescope