Superluminal motion in a compact steep spectrum radio source 3C 138

Abstract

We present the results of 5 GHz VLBI observations of a compact steep spectrum source 3C 138. The data are consistent with the western end being the location of the central activity. The observed offset between different frequencies in the central region of 3C 138 can be accounted for by a frequency dependent shift of the synchrotron self-absorbed core. Our new measurements confirm the existence of a superluminal motion, but its apparent velocity of 3.3c is three times slower than the reported one. This value is consistent with the absence of parsec-scale counter-jet emission in the inner region, but seems still too high to allow the overall counter-jet to be seen in terms of Doppler boosting of an intrinsically identical jet. Either an interaction of jet with central dense medium, or an intrinsically asymmetrical jet must be invoked to reconcile the detected superluminal speed with the observed large scale asymmetry in 3C 138.

5 pages including 3 ps figures and 1 table, LaTex2e, accepted for publication in Astronomy and Astrophysics

References in corpus (1)

• The compact core-jet region of the superluminal quasar 3C216

Cited by in corpus (6)

• The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• Spitzer Observations of 3C Quasars and Radio Galaxies: Mid-Infrared Properties of Powerful Radio Sources
• Kinematics of the parsec-scale radio jet in 3C48
• Jet Properties of Compact Steep-Spectrum Sources and an Eddington-Ratio-Driven Unification Scheme of Jet Radiation in Active Galactic Nuclei
• The Center of Activity in the CSS Superluminal Source 3C 138
• Phase-reference VLBI Observations of the Compact Steep-Spectrum Source 3C 138