Unexpected High Brightness Temperature 140 PC from the Core in the Jet of 3C 120

Abstract

We present 1.7, 5, 15, 22 and 43 GHz polarimetric multi-epoch VLBA observations of the radio galaxy 3C 120. The higher frequency observations reveal a new component, not visible before April 2007, located 80 mas from the core (which corresponds to a deprojected distance of 140 pc), with a brightness temperature about 600 times higher than expected at such distances. This component (hereafter C80) is observed to remain stationary and to undergo small changes in its brightness temperature during more than two years of observations. A helical shocked jet model - and perhaps some flow acceleration - may explain the unusually high Tb of C80, but it seems unlikely that this corresponds to the usual shock that emerges from the core and travels downstream to the location of C80. It appears that some other intrinsic process in the jet, capable of providing a local burst in particle and/or magnetic field energy, may be responsible for the enhanced brightness temperature observed in C80, its sudden appearance in April 2007, and apparent stationarity.

5 pages, 5 figures Accepted to be published in ApJ Letters

References in corpus (7)

• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. V. Multi-epoch VLBA Images
• Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior
• Dynamics and High Energy Emission of the Flaring HST-1 Knot in the M 87 Jet
• Disk-Jet Connection in the Radio Galaxy 3C 120
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. VII. Blazar Jet Acceleration
• Faraday rotation and polarization gradients in the jet of 3C~120: Interaction with the external medium and a helical magnetic field?
• Multi-wavelength Variability of the Broad Line Radio Galaxy 3C 120

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