Discovery of a subparsec radio counterjet in the nucleus of centaurus A

Dayton L. Jones, Steven J. Tingay, David W. Murphy, David L. Meier, David L. Jauncey, John E. Reynolds, Anastasios K. Tzioumis, Robert A. Preston, Peter M. Mcculloch, Marco E. Costa, Athol J. Kemball, George D. Nicolson, Jonathan F.H. Quick, Edward A. King, James E.J. Lovell, R. W. Clay, Richard H. Ferris, R. G. Gough, M. W. Sinclair, S. P. EllingsenP. G. Edwards, P. A. Jones, T. D. Van Ommen, Paul Harbison, Victor Migenes

Research output: Contribution to journalArticlepeer-review


A subparsec scale radio counterjet has been detected in the nucleus of the closest radio galaxy, Centaurus A (NGC 5128), with VLBI imaging at 2.3 and 8.4 GHz. This is one of the first detections of a VLBI counterjet and provides new constraints on the kinematics of the radio jets emerging from the nucleus of Cen A. A bright, compact core is seen at 8.4 GHz, along with a jet extending along P.A. 51°. The core is completely absorbed at 2.3 GHz. Our images show a much wider gap between the base of the main jet and the counterjet at 2.3 GHz than at 8.4 GHz and also that the core has an extraordinarily inverted spectrum. These observations provide evidence that the innermost 0.4-0.8 pc of the source is seen through a disk or torus of ionized gas which is opaque at low frequencies due to free-free absorption.

Original languageEnglish (US)
Pages (from-to)L63-L65
JournalAstrophysical Journal
Issue number2 PART II
StatePublished - 1996
Externally publishedYes


  • Accretion, accretion disks
  • Galaxies: active
  • Galaxies: individual (NGC 5128, Centaurus A)
  • Galaxies: jets
  • Galaxies: nuclei

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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