Astronomy Colloquium

Using the FIRE spectrometer at Magellan, we have gathered deep IR spectra of 40 quasars at z > 5.8 and over 100 at z > 4, providing at last a statistically significant pathlength for studying intervening avy-element absorption systems near the epoch of reionization.  I will discuss the status of these absorption measurements, with particular emphasis on detections at z > 5.5.  These relatively rare absorbers have the potential to place joint bounds on heavy element pollution and the ionizing background radiation field at early times.  I will describe how high resolution optical and IR measurements may be combined to constrain these systems' gas-phase metallicity, even when Gunn-Peterson absorption saturates the HI profiles into an unusuable condition.  I will close with some discussion of future prospects for
this work using instruments for existing telescopes and ELTs.