An X-ray survey of a complete sample of 3CR radio galaxies

1998

Monthly Notices RAS

We report on ROSAT HRI observations of the nearby powerful radio galaxies 3C 33 and 3C 111, which both have detected optical hot spots. We find nuclear X-ray sources in both objects, but no X-ray emission from the hot spots. This confirms the presence of a high-energy cutoff in the spectrum of synchrotron-emitting electrons. Since these electrons necessarily scatter the synchrotron photons by the inverse-Compton process, our upper limits on the X-ray fluxes of the hot spots allow us to set lower limits of a few nanotesla on their magnetic flux density, close to or greater than the fields implied by equipartition of energy between radiating particles and magnetic field.

Section: C33supporting

confidence: 91%

Magnetic field strengths in the hotspots of 3C 33 and 111

Hardcastle

Birkinshaw

1998

Monthly Notices RAS

“…Focussing X-ray optics have the major advantage of decreasing the background, and so Einstein was the first mission to detect some tens of radio galaxies in soft X-rays (e.g. Fabbiano et al 1984) and to separate components in nearby objects such as Cen A and M 87 (Feigelson et al 1981, Schreier et al 1982. The mission contributing most to the subject over the last decade has been ROSAT.…”

Section: Observational Biasesmentioning

confidence: 99%

The gaseous environments of radio galaxies

2002

New Astronomy Reviews

X-ray emission traces the gaseous environments of radio sources. The medium must be present for jet confinement, but what are its influence on jet fuelling, dynamics, propagation, and disruption? The observational situation is both complicated and enriched by radio sources being multi-component X-ray emitters, with several possible regions of non-thermal emission. Recent work, primarily based on sensitive ROSAT pointings, is used to contrast the X-ray emission and environments of radio sources with (a) low power, (b) high power at high redshift, (c) high power at lower redshift, and (d) GHz peaked spectrum emission. The trends in external gas density and pressure near extended radio structures are reviewed. Imminentlyavailable X-ray measurements with vastly improved resolution and sensitivity have great potential for resolving many open issues.

“…The evidence in favor of each interpretation provides the motivation for this paper, which uses spectroscopy of the X-ray cores to distinguish the two possibilities. On the one hand, it has been suggested that at least a fraction of the nuclear X-ray emission of radio galaxies has an origin at the unresolved base of a parsec-scale radio jet (e.g., Fabbiano et al 1984). The best pieces of evidence in favor of this hypothesis are the observed correlations between the Röntgensatellit (ROSAT ) X-ray and Very Large Array (VLA) radio core fluxes and luminosities measured in the B2 (Canosa et al 1999) and 3CRR ) samples, supporting a nuclear jet-related origin for at least the soft X-ray emission.…”

Section: Introductionmentioning

confidence: 99%

ChandraandXMM‐NewtonObservations of a Sample of Low‐Redshift FR I and FR II Radio Galaxy Nuclei

Evans

Hardcastle

et al. 2006

ApJ

189

245

We present spectral results from Chandra and XMM-Newton observations of a sample of 22 low-redshift (z < 0:1) radio galaxies and consider whether the core emission originates from the base of a relativistic jet, or an accretion flow, or contains contributions from both. We find correlations between the unabsorbed X-ray, radio, and optical fluxes and luminosities of FR I-type radio-galaxy cores, implying a common origin in the form of a jet. On the other hand, we find that the X-ray spectra of FR II-type radio galaxy cores are dominated by absorbed emission, with N H k 10 23 atoms cm À2 , which is likely to originate in an accretion flow. We discuss several models that may account for the different nuclear properties of FR I-and FR II-type cores and also demonstrate that both heavily obscured, accretion-related and unobscured, jet-related components may be present in all radio galaxy nuclei. Any absorbed, accretion-related components in FR I-type galaxies have low radiative efficiencies.