Abstract

A technique is presented to deconvolve variable Seyfert 1 profiles that consist of components that differ in radial velocity coverage and time scale of variability.

Introduction

Variable structure in the emission-line profiles of AGN can in principle be used to map out the kinematics of the broad-line region (BLR). However, profile variations can also occur if the profile consists of more than one component and each component is variable in flux on a different time scale (Peterson et al. 1990). In order to use profile variations as a probe of the BLR, it is important to devise techniques to deconvolve components that may represent physically distinct emission-line regions. One possible technique will be outlined using data obtained from the 1989 campaign to monitor the Seyfert 1 galaxy NGC 5548 with the International Ultraviolet Explorer (IUE), as well as IUE spectra obtained by Webb and Crenshaw in April, 1990, when NGC 5548 was in a particularly low state.

Figure 1 shows that the profile of C IV λ1550 is much narrower in the low state, suggesting that there is a strong narrow component that has not varied as much as the rest of the profile. In addition, it is clear that excess emission in the blue wing, which Peterson et al. (1990) claim is a distinct component that varies on a longer timescale than the majority of the broad-line flux, has nearly disappeared.