Discovery of a Sub-Parsec Radio Counterjet in the Nucleus of Centaurus A

Abstract

A sub-parsec 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 degrees. 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.

3 pages, 2 postscript figures, scheduled for publication in August 1, 1996 issue of Ap.J. Letters

Cited by in corpus (53)

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• Chandra Observations of the X-ray Jet in Centaurus A
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• TANAMI monitoring of Centaurus A: The complex dynamics in the inner parsec of an extragalactic jet
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• Modelling the Infrared continuum of Centaurus A
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• Disentangling the Circumnuclear Environs of Centaurus A: III. An Inner Molecular Ring, Nuclear Shocks and the CO to warm H2 interface
• Signatures of Relativistic Helical Motion in the Rotation Measures of AGN Jets
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• Integral-field spectroscopy of Centaurus A nucleus
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• BeppoSAX Observations of Centaurus A: the Hard Continuum and the Iron Line Feature
• Limits on X-ray Polarization at the Core of Centaurus A as Observed with the Imaging X-ray Polarimetry Explorer
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• HST infrared imaging polarimetry of Centaurus A: implications for the unified scheme and the existence of a mis-directed BL Lac nucleus
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