The NV/CIV ratio in high redshift radio galaxies

Deep Keck spectropolarimetry has been obtained of a sample of powerful radio galaxies with z � 2.5±1. In addition to a clear 2200u dust scattering/extinction signature and an inverse correlation between the degree of continuum polarization and the Lyman-� emission line strength (relative to C IV), we find an intriguing positive correlation between the N V/C IV ratio and the polarization. The line ratio, which varies by almost a dex amongst objects having a very similar ionization state, is most likely to indicate an abundance ratio. We speculate that the correlation with polar- ization represents a connection between nitrogen enhancement and dust production following a major starburst event connected with the birth of the quasar.