A STUDY OF THE BALDWIN EFFECT IN THE IUE DATA SET

We have investigated the controversial relation between the continuum luminosity and the C IV λ550 emission-line strength in the spectra of quasars, commonly referred to as the Baldwin Effect, as a possible indicator of absolute luminosity, We have used all available quasar spectra in the IUE archives which have C IV and/or Lyα shifted into the IUE waveband and several high-redshift samples gathered from the literature. Multiple IUE observations of variable Seyfert galaxies have also been included to allow the evaluation of the effects of variability and to establish the low luminosity end of the relation. The data, which include 244 spectra of 101 quasars, and 344 spectra of 88 Seyferts, have been uniformly extracted using an optimal extraction routine with considerable improvement over IUESIPS. We conclude that the Baldwin Effect does represent a physical correlation between the continuum and the C IV λ1550 equivalent width rather than a consequence of selection effects. In addition to the C IV results, we find a similar relation for the Lyα emission line. The significance of these findings are muted by the large scatter inherent in the relation which prevents placing meaningful constraints on the value of q0. There are indications that variability may be the main source of dispersion in the relation, and that this may be significantly reduced by time averaging over the luminosity variations of active galactic nuclei (AGNs).