Astron. Astrophys. 338, 405-412 (1998)

Kinematics of the narrow-line region of NGC 1068 ^*

M. Dietrich and S.J. Wagner

Landessternwarte Heidelberg, Königstuhl, D-69117 Heidelberg, Germany

Received 7 May 1998 / Accepted 8 July 1998

Abstract

We investigated the kinematics of the Narrow Line Region of NGC 1068. In order to study the kinematics and to determine whether the unusual broad line width can be attributed to motion of NLR clouds in a deep gravitational potential or to expanding shocks, we carried out spatially resolved echelle spectroscopy. High spectral resolution enables the identification of individual clouds in long slit spectra even if their angular separation is much smaller than the seeing limited resolution of ground-based instruments.

Most of the [OIII] line emission can be attributed to 12 clouds with an average angular separation of about . These clouds differ in peak velocity by up to 2000 km s^-1, spanning the whole range of the integrated line profile with FWHM = 1150 km s^-1. The clouds do not delineate a simple rotational velocity field. We find evidence for shocks due to the interaction of the radio jet with the ambient NLR gas. The clouds which are attributed to shocks have a width of 350 km s^-1 to 600 km s^-1 while clouds with FWHM 200 km s^-1 seem to follow a circular velocity field. Therefore, the line width of individual clouds are an essential contribution to the integrated line width of the NLR of NGC 1068 which is not due only to gravitational forces but shocks playing an important role.

Key words: galaxies: active galaxies: Seyfert quasars: emission lines galaxies: individual NGC 1068

* Based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: M. Dietrich, (mdietric@lsw.uni-heidelberg.de)

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Contents

• 1. Introduction
• 2. Observations and reduction
• 3. Analysis of Echelle spectrograms
  • 3.1. The method of sub-arcsec mapping
  • 3.2. Decomposition of the [OIII] 5007 line profile
• 4. Results and discussion
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: September 14, 1998
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