Exploring low luminosity quasar diversity at z ≈ 2.5 with the Gran Telescopio Canarias

We present preliminary results from a pencil-beam spectroscopic survey of low-luminosity quasars at z≈2.2-2.5. Our goal is to compare these sources with low redshift analogues of similar luminosity. High s/n and moderate resolution spectra were obtained for 15 sources using the faint object spectrograph Osiris on the 10m Gran Telescopio Canarias. The new data make possible an almost unprecedented comparison between sources with the same (moderate) luminosity at widely different cosmic epochs. Preliminary analysis of our spectra confirms the presence of a relatively evolved population of quasars radiating at modest L/LEdd. A notable difference between the low and high z quasars may involve the presence of lower metallicity quasars at high redshift. © 2014 Published by Elsevier Ltd.