The variable broad emission line spectrum of 4C 37.43.

Abstract

The results of a short campaign to monitor the quasar 4C37.43 using the International Ultraviolet Explorer (IUE) satellite are presented. Combining these data with archive data we find clear evidence for ultraviolet continuum and Ly α emission line variability. Most of the Ly α variability occurs in the wings of the line. The C IV λ1549 line may vary in a similar way to Ly α, but no evidence is found for C III] λ 1909 variability. Examination of both unpublished and published optical spectra indicate that the Hβ line varied during the same period as Ly α and C IV. The emission line variability time-scales do not conflict with the predictions of the standard photoionized model of the broad line region, although the light curves are poorly sampled. The Ly α, C IV, and O VI λ1034 line profiles are similar, and have stronger line wings relative to the core than the C III] line. The Ly α to Hβ line ratio is fairly constant in the wings, but is higher in the core. The line ratio in the wings is consistent with emission from a high column density region. The higher ratio in the line core agrees reasonably well with the standard model. The line core emission may arise from a lower density region than the wings.