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AGN jet kinetic power and the energy budget of radio galaxy lobes


Godfrey, LEH and Shabala, SS, AGN jet kinetic power and the energy budget of radio galaxy lobes, The Astrophysical Journal: An International Review of Astronomy and Astronomical Physics, 767, (1) Article 12. ISSN 0004-637X (2013) [Refereed Article]

Copyright Statement

Copyright 2013 The American Astronomical Society

DOI: doi:10.1088/0004-637X/767/1/12


Recent results based on the analysis of radio galaxies and their hot X-ray emitting atmospheres suggest that non-radiating particles dominate the energy budget in the lobes of FRI radio galaxies, in some cases by a factor of more than 1000, while radiating particles dominate the energy budget in FRII radio galaxy lobes. This implies a significant difference in the radiative efficiency of the two morphological classes. To test this hypothesis, we have measured the kinetic energy flux for a sample of 3C FRII radio sources using a new method based on the observed parameters of the jet terminal hotspots, and compared the resulting Qjet-Lradio relation to that obtained for FRI radio galaxies based on X-ray cavity measurements. Contrary to expectations, we find approximate agreement between the Qjet-Lradio relations determined separately for FRI and FRII radio galaxies. This result is ostensibly difficult to reconcile with the emerging scenario in which the lobes of FRI and FRII radio galaxies have vastly different energy budgets. However, a combination of lower density environment, spectral aging and strong shocks driven by powerful FRII radio galaxies may reduce the radiative efficiency of these objects relative to FRIs and counteract, to some extent, the higher radiative efficiency expected to arise due to the lower fraction of energy in non-radiating particles. An unexpected corollary is that extrapolating the Qjet-Lradio relation determined for low power FRI radio galaxies provides a reasonable approximation for high power sources, despite their apparently different lobe compositions.

Item Details

Item Type:Refereed Article
Keywords:galaxies: active
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Shabala, SS (Associate Professor Stas Shabala)
ID Code:84208
Year Published:2013
Web of Science® Times Cited:86
Deposited By:Mathematics and Physics
Deposited On:2013-04-30
Last Modified:2017-11-03

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