Long-term x-ray stability and ultraviolet variability of the ionized absorption in NGC 3783

A. E. Scott, W. N. Brandt, E. Behar, D. M. Crenshaw, J. R. Gabel, R. R. Gibson, S. Kaspi, S. B. Kraemer, T. J. Turner

Research output: Contribution to journalArticlepeer-review


We present the results of recent Chandra High-Energy Transmission Grating Spectrometer and Hubble Space Telescope Cosmic Origins Spectrograph observations of the nearby Seyfert 1 galaxy NGC 3783, which show a strong, nonvarying X-ray warm absorber and physically related and kinematically varying UV absorption. We compare our new observations to high-resolution, high signal-to-noise archival data from 2001, allowing a unique investigation into the long-term variations of the absorption over a 12 yr period. We find no statistically significant changes in the physical properties of the X-ray absorber, but there is a significant drop of ∼40% in the UV and X-ray flux and a significant flattening of the underlying X-ray power-law slope. Large kinematic changes are seen in the UV absorbers, possibly due to radial deceleration of the material. Similar behavior is not observed in the X-ray data, likely due to its lower-velocity resolution, which shows an outflow velocity of vout ∼ -655 km s-1 in both epochs. The narrow iron Kα emission line at 6.4 keV shows no variation between epochs, and its measured width places the material producing the line at a radial distance of ∼0.03 pc from the central black hole.

Original languageEnglish
Article number105
JournalAstrophysical Journal
Issue number2
StatePublished - 20 Dec 2014


  • Galaxies: Active
  • Galaxies: Individual (NGC 3783)
  • Galaxies: Seyfert
  • X-rays: Galaxies

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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