AAS 204th Meeting, June 2004
Session 50 AGN Mass Ejection and X-ray/UV Connection
Topical Session, Wednesday, June 2, 2004, 8:30-10:00am, 10:45am-12:30pm, 707/709

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[50.03] The Geometry and Physical Conditions in AGN Outflows: New Constraints from Intensive UV Observations

J.R. Gabel (CASA/University of Colorado), D.M. Crenshaw (Georgia State University), S.B. Kraemer (The Catholic University of America), N. Arav (CASA/University of Colorado), NGC 3783 Monitoring Team

We present results from intensive UV observing campaigns of the intrinsic absorption in two Seyfert 1 galaxies, NGC 3783 and Mrk 279. These observations obtained with FUSE and HST/STIS yielded the highest quality spectra of mass outflow in Seyferts currently available.

For NGC 3783, analyses of both the high signal-to-noise averaged UV spectrum and absorption variability detected in multi-epoch (18) observations provide unprecedented constraints on the geometry, physical conditions, and location of the intrinsic absorbers. Some highlights of this study are: 1) The detailed solution of the line-of-sight absorption covering factors. Complex velocity-dependent and ionization-dependent structure is found in the absorbers, and the individual covering factors of distinct background emission sources are separated, providing unique insight into the absorption/emission geometry. 2) Tight constraints on the volume density, ionization structure, and total column density in the UV absorbers are derived from absorption line diagnostics and photoionization modeling of the variable absorption spectrum. This gives the location and physical thickness of the absorbers. 3) The rare detection of variability in the radial velocity of an outflow component: one kinematic component of UV absorption exhibited a decreasing outflow velocity on approximately yearly timescales. 4) The connection of the UV and Xray absorption as seen by the identical kinematic structure in the high S/N mean spectra and comparison of results from photoionization modeling.

For Mrk 279, we make use of the high signal-to-noise spectrum and the unblended intrinsic absorption features to derive detailed fits to the covering factors (of individual emission sources) and optical depths of the UV absorbers. We compare our global fitting to traditional methods of measuring the absorption parameters in terms of the increased accuracy of the measurements and the novel geometric-kinematic constraints available with this technique.

The author(s) of this abstract have provided an email address for comments about the abstract: jgabel@colorado.edu

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