The Ionized Gas and Nuclear Environment in NGC 3783. III. Detection of a Decreasing Radial Velocity in an Intrinsic UV Absorber

Authors: Gabel, J.R.6, Crenshaw, D.M.5, Kraemer, S.6, Brandt, W.N.1, George, I.M.3,4, Netzer, H.2, Hamann, F.W.7, Kaiser, M.E.8, Kaspi, S.1,2, Koratkar, A.9, Kriss, G.A.8,9, Mathur, S.10, Mushotzky, R.F.3, Nandra, K.3,11, Peterson, B.M.10, Shields, J.C.12, Turner, T.J.3,4, Zheng, W.8,
Affiltns: 1Penn State Univ, 2Tel Aviv University, 3 LHEA, NASA/GSFC, 4 JCA, UMBC, 5 Georgia State University, 6 Catholic University of America, 7Univ. Florida, 8Johns Hopkins Univ, 9STScI, 10Ohio State Univ, 11 USRA, 12Ohio Univ
Journal: ApJ, in press
Publn Date: tbd

Summary

We report an intrinsic absorber with decreasing outflow velocity in the Seyfert 1 galaxy NGC 3783. This is the first detection of a change in radial velocity in an outflow associated with a Seyfert galaxy. These results are based on measurements from 18 observations with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, obtained between 2000 February and 2002 January. In two intervals separated by ~13 and 9 months, the absorption lines in the kinematic component with highest outflow velocity exhibited mean redward velocity shifts of ~35 and 55 km/s, respectively. The rate of velocity decrease was 2.2 +/- 0.6 times more rapid in the second interval. No variations in absorption velocities were detected in the other kinematic components. We explore potential interpretations of the observed velocity shifts: radial deceleration of the UV absorber due to a change in either the speed or direction of motion of the outflow, and the evolution of a continuous flow across our line of sight to the emission source.

Figures: Fig1a Fig1b Fig2 Fig3 Fig4

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See Also

The Ionized Gas and Nuclear Environment in NGC 3783 papers:
I Time-averaged 900 ks Chandra Grating Spectroscopy
Kaspi, S., et al., 2002, ApJ, 574, 643
II Averaged HST/STIS and FUSE Spectra
Gabel, J.R., et al., 2003, ApJ, 583, 178
III Detection of a Decreasing Radial Velocity in an Intrinsic UV Absorber
Gabel, J.R., et al., 2003, ApJ, 595, 120
IV Variability and Modeling the 900 ks Chandra Spectrum
Netzer, H., et al., 2003, ApJ, 599, 933
V Variability and Modeling of the Intrinsic Ultraviolet Absorption
Gabel, J.R., 2005, ApJ, submitted