paper

Size dependence of the radio luminosity - mechanical power correlation in radio galaxies

arXiv:1304.6089 · doi:10.1088/0004-637X/769/2/129

Abstract

We examine the relationship between source radio luminosity and kinetic power in Active Galactic Nucleus (AGN) jets. We show that neglecting various loss processes can introduce a systematic bias in the jet powers inferred from radio luminosities for a sample of radio galaxies. This bias can be corrected for by considering source size as well as radio luminosity; effectively the source size acts as a proxy for source age. Based on a sample of FR-II radio sources with jet powers derived from the measured hotspot parameters, we empirically determine a new expression for jet power that accounts for the source size, Q_jet / 10^{36} W = 1.5 (L_151 / 10^{27} W/Hz)^{0.8} (1+z)^{1.0} (D / kpc)^{0.58 \pm 0.17}, where D is source size and L_151 the 151 MHz radio luminosity. By comparing a flux-limited and volume-limited sample, we show that any derived radio luminosity - jet power relation depends sensitively on sample properties, in particular the source size distribution and the size-luminosity correlation inherent in the sample. Such bias will affect the accuracy of the kinetic luminosity function derived from lobe radio luminosities and should be treated with caution.

8 pages, 5 figures, accepted for publication in ApJ

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