Near - Infrared Spectroscopy of the High - Redshift Quasar S

We present near-infrared (observed frame) spectra of the high-redshift quasar S4 0636]68 at z\ 3.2, which was previously thought to be one of a group of ““ strong ÏÏ Fe II emitters [i.e., F(Fe II jj4434È 4684)/F(Hb)[ 1]. Our K-band spectrum clearly shows emission lines of Hb and [O III] jj4959, 5007, as well as optical Fe II emission. Our computed value of F(Fe II jj4434È4684)/F(Hb) ^ 0.8 for S4 0636]68 is less than previously thought and, in fact, is comparable to values found for radio-loud, Ñat-spectrum, low-z quasars. Therefore S4 0636]68 appears not to be a strong optical Fe II emitter. Although more than half of the high-z quasars observed to date are still classiÐed as strong optical Fe II emitters, (58) their Fe II/Hb ratios, for the most part, follow the same trend as do those of low-z quasars, i.e., an anticorrelation in EW(Fe II)/EW(Hb) versus EW([O III])/EW(Hb), with radio-loud quasars having a mean value of EW(Fe II)/EW(Hb) approximately half that of radio-quiet quasars at comparable values of EW([O III])/EW(Hb).