The active nuclei of z < 1.0 3CRR radio sources

By M. Hardcastle, D. Evans, Judith Croston. 2009

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We combine Chandraand XMM-NewtonX-ray data from our previous papers with new X-ray observations and with Spitzer mid-infrared data in order to study the nature of the nuclei o f radio galaxies and radio-loud quasars with z < 1.0 from the 3CRR sample. The significant increase in sample size over our previous work, the reduction of bias in the sample as a result of new observations, and the availability of more mid-infrared data allow us to show conclusively that almost all objects classed as low-excitation ra dio galaxies in optical spectroscopic studies lack a radiatively efficient active nucleus. We show that the distribution of absorbing columns in the narrow-line radio galaxies differs from the population of X-ray-selected radioquiet type-2 quasars and from that in local Seyfert 2s. We comment on the current evidence for the nature of the soft X-ray component in radio-galaxy nuclear spectra, concluding that a jet origin for this component is very hard to evade. Finally, we discuss the recently discovered ‘fundamental plane’ of black hole activity, showing th at care must be taken when placing radio-loud AGN on such diagnostic diagrams.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/bd119f30da5c069ea922c64094ef3eb627c50b2f

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Citations in the corpus

BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, background): “This has been found to be the case for radio galaxies (Hardcastle et al. 2006, 2009), which very often show additional unobscured power-law emission.”
Radio galaxies and feedback from AGN jets (2020, background): “Work on the mid-IR and X-ray properties of the LERGs, however, ruled this possibility out (Chiaberge et al., 2002; Whysong and Antonucci, 2004; Hardcastle et al., 2006, 2009) by showing that there was no evidence for either heavily obscured X-ray emission or re-radiation of obscured emission in the…”
Using the Fundamental Plane of black hole activity to distinguish X-ray processes from weakly accreting black holes (2011, methodology): “However, we refer the reader to Hardcastle et al. (2009) for an FP study that overcomes some of the above systematics: with X-ray spectral modelling, Hardcastle et al. (2009) are able to compare accretion-related versus jet-related X-ray emission for a sample of unbeamed radio galaxies.”
The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, background): “5.3.3 Radio-loud sources – Hardcastle et al. (2009) and Mason et al. (2012) Hardcastle, Evans & Croston (2009) investigate multiwavelength correlations for radio-loud AGN, namely the low-redshift 3CCR sources.”