Journal Article

The relationship between beam power and radio power for classical double radio sources

Ruth. A. Daly, Trevor B. Sprinkle, Christopher P. O’Dea, Preeti Kharb and Stefi A. Baum

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 3, pages 2498-2502
Published in print July 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21060.x
The relationship between beam power and radio power for classical double radio sources

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Beam power is a fundamental parameter that describes, in part, the state of a supermassive black hole system. Determining the beam powers of powerful classical double radio sources requires substantial observing time, so it would be useful to determine the relationship between beam power and radio power so that radio power could be used as a proxy for beam power. A sample of 31 powerful classical double radio sources with previously determined beam and radio powers is studied; the sources have redshifts between about 0.056 and 1.8. It is found that the relationship between beam power, Lj, and radio power, P, is well described by log Lj≈ 0.84(±0.14)log P+ 2.15(±0.07), where both Lj and P are in units of 1044 erg s−1. This indicates that beam power is converted to radio power with an efficiency of about 0.7 per cent. The ratio of beam power to radio power is studied as a function of redshift; there is no significant evidence for redshift evolution of this ratio over the redshift range studied. The relationship is consistent with empirical results obtained by Cavagnolo et al. for radio sources in gas-rich environments, which are primarily Fanaroff–Riley type I sources, and with the theoretical predictions of Willott et al.

Keywords: black hole physics; galaxies: active

Journal Article.  4199 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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