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

Jack Gabel, D. Michael Crenshaw, Steven B. Kraemer, W. N. Brandt, Ian M. George, Frederick W. Hamann, Mary Elizabeth Kaiser, Shai Kaspi, Gerard A. Kriss, Smita Mathur, Richard F. Mushotzky, Klrpal Nandra, Hagai Netzer, Bradley M. Peterson, Joseph C. Shields, T. J. Turner, Wei Zheng

Research output: Contribution to journalArticle

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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 s1, 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.

Original languageEnglish
Pages (from-to)120-126
Number of pages7
JournalAstrophysical Journal
Issue number1 I
Publication statusPublished - Sep 20 2003
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Nuclear and High Energy Physics

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