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Mutual distance dependence drives the observed jet-power–radio-luminosity scaling relations in radio galaxies


Godfrey, LEH and Shabala, SS, Mutual distance dependence drives the observed jet-power-radio-luminosity scaling relations in radio galaxies, Monthly Notices of the Royal Astronomical Society, 456, (2) pp. 1172-1184. ISSN 0035-8711 (2016) [Refereed Article]


Copyright Statement

Copyright 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

DOI: doi:10.1093/mnras/stv2712


The kinetic power of radio jets is a quantity of fundamental importance to studies of the AGN feedback process and radio galaxy physics. A widely used proxy for jet power is the extended radio luminosity. A number of empirical methods have been used to calibrate a scaling relationship between jet power (Q) and radio luminosity (L) of the form log (Q) = βL log (L) + C. The regression slope has typically been found to be βL ∼ 0.7–0.8. Here we show that the previously reported scaling relations are strongly affected by the confounding variable, distance. We find that in a sample of FRI X-ray cavity systems, after accounting for the mutual distance dependence, the jet power and radio luminosity are only weakly correlated, with slope βL ≈ 0.3: significantly flatter than previously reported. We also find that in previously used samples of high-power sources, no evidence for an intrinsic correlation is present when the effect of distance is accounted for. Using a simple model we show that βL is expected to be significantly lower in samples of FRI radio galaxies than it is for FRIIs, due to the differing dynamics for these two classes of radio source. For FRI X-ray cavity systems the model predicts βL(FRI) ≳ 0.5 in contrast to FRII radio galaxies, for which βL(FRII) ≳ 0.8. We discuss the implications of our finding for studies of radio mode feedback, and radio galaxy physics.

Item Details

Item Type:Refereed Article
Keywords:galaxies: active, galaxies: jets, radio continuum: galaxies
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:107316
Year Published:2016
Funding Support:Australian Research Council (DE130101399)
Web of Science® Times Cited:39
Deposited By:Mathematics and Physics
Deposited On:2016-03-10
Last Modified:2017-11-03
Downloads:157 View Download Statistics

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