OPTICAL-LINES IN HIGH-REDSHIFT QUASI-STELLAR OBJECTS - BALMER LINES, [O-III], AND FE-II

We present infrared spectroscopy of familiar rest-frame optical emission lines in the four bright z approximately 2.5 QSOs Q0933 + 733, Q1255 + 317, Q1246 - 057, and Q1413 + 117. The spectral regions around Halpha and around Hbeta, including the [O III] lambdalambda5007, 4959 lines and optical Fe II complexes, were observed with sufficient resolution and sensitivity to allow the deblending of the different features. We discuss the emission-line properties of these QSOs in the context of their lower redshift, lower luminosity counterparts. The rest-frame optical Fe II complexes around Hbeta are detected in high redshift QSOs for the first time, and are particularly strong compared to lower redshift objects. Of these QSOs, only Q1413 + 117 shows detectable [O III] emission, and this emission is abnormally strong for a broad absorption line QSO. The observation of Q1413 + 117 is the first infrared spectrum of a lensed QSO. The Balmer lines have lower equivalent widths than low-redshift, lower-luminosity QSOs, and there is no evidence for reddening.