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J. R. Gabel (CUA/GSFC), D. M. Crenshaw (GSU), S. B. Kraemer (CUA/GSFC), NGC 3783 Monitoring Team
The Seyfert 1 galaxy NGC 3783 has been observed at 18 epochs with HST/STIS and 6 epochs with FUSE as part of an intensive multiwavelength monitoring campaign designed to probe the mass outflow associated with its AGN. We present measurements and preliminary models of variability in the intrinsic absorption in the UV and far-UV spectra. The UV continuum light curve, sampled on day to month timescales, exhibits a peak variation of a factor of ~ 3 during the campaign, with variations of 1.5--2 found on timescales as short as ~ 15 days. In the highest outflow velocity component (vr=-1320 km s-1), column densities of the low ionization species (Si IV, C II, and C III*) are found to vary by factors up to ~ 2--3 during the campaign. These variations are inversely correlated with the continuum flux, indicating they are driven by changes in the ionizing continuum. There are no detectable changes in the apparent absorption strenths in the higher ionization lines (C IV, N V, O VI) in this component, supporting our previous claim that these lines are saturated and their absorption depths are determined entirely by the covering factors. In the other two strong absorption components (vr=-724, -548 km s-1), the C IV column is found to vary inversely with the continuum flux. We have coadded multiple observations to obtain representative low and high state spectra with high signal-to-noise for modeling. We have run preliminary photoionization models and have derived constraints on the physical conditions in each kinematic absorption component (i.e., ionization parameter, density, total column density, radial depth, distance from ionizing source).
The author(s) of this abstract have provided an email address for comments about the abstract: gabel@iacs.gsfc.nasa.gov
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.