An optical inverse-Compton hotspot in 3C 196?

Hardcastle, M. J.

doi:10.1051/0004-6361:20010687

Cited by 18 publications

(25 citation statements)

References 19 publications

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“…Cygnus A, γ min ∼ 300-400 (Carilli et al 1991;Lazio et al 2006;Hardcastle 2001); 3C295, γ min ∼ 800 (Harris et al 2000;Hardcastle 2001); 3C123, γ min ∼ 1000 Hardcastle 2001); PKS 1421−490, γ min ∼ 650 (this work). Leahy et al (1989) presented evidence for a low-energy cutoff in two other hot spots: 3C268.1 and 3C68.1.…”

Section: Introductionmentioning

confidence: 61%

“…In both these objects, the hotspot radio spectra are significantly flatter between 150 MHz and 1.5 GHz than they are above 1.5 GHz, which suggests a similar value of γ min to those listed above, provided the hotspot magnetic field strengths are similar. More recently, Hardcastle (2001) reported on a possible detection of an optical inverse Compton hot spot in the quasar 3C196. By modeling the synchrotron self-Compton (SSC) emission and assuming a magnetic field strength close to the equipartition value, they inferred a cutoff Lorentz factor γ min ∼ 500.…”

Section: Introductionmentioning

confidence: 99%

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A Multiwavelength Study of the High Surface Brightness Hot Spot in PKS 1421–490

Godfrey

Bicknell

Lovell

et al. 2009

ApJ

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Long Baseline Array imaging of the z = 0.663 broadline radio galaxy PKS 1421−490 reveals a 400 pc diameter high surface brightness hot spot at a projected distance of ∼40 kpc from the active galactic nucleus. The isotropic X-ray luminosity of the hot spot, L 2-10 keV = 3 × 10 44 ergs s −1 , is comparable to the isotropic X-ray luminosity of the entire X-ray jet of PKS 0637−752, and the peak radio surface brightness is hundreds of times greater than that of the brightest hot spot in Cygnus A. We model the radio to X-ray spectral energy distribution using a one-zone synchrotron self-Compton model with a near equipartition magnetic field strength of 3 mG. There is a strong brightness asymmetry between the approaching and receding hotspots and the hot spot spectrum remains flat (α ≈ 0.5) well beyond the predicted cooling break for a 3 mG magnetic field, indicating that the hotspot emission may be Doppler beamed. A high plasma velocity beyond the terminal jet shock could be the result of a dynamically important magnetic field in the jet. There is a change in the slope of the hotspot radio spectrum at GHz frequencies, which we model by incorporating a cutoff in the electron energy distribution at γ min ≈ 650, with higher values implied if the hotspot emission is Doppler beamed. We show that a sharp decrease in the electron number density below a Lorentz factor of 650 would arise from the dissipation of bulk kinetic energy in an electron/proton jet with a Lorentz factor Γ jet 5.

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Section: Introductionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

A Multiwavelength Study of the High Surface Brightness Hot Spot in PKS 1421–490

Godfrey

Bicknell

Lovell

et al. 2009

ApJ

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“…The large number of detected X-ray hot spots is interesting in itself, given that calculations based on SSC emission at equipartition suggested that only the few brightest hot spots would be detected with Chandra (e.g., Hardcastle 2001). In order to assess quantitatively the extent to which the new detections conflict with an SSC model, we decided to fit a simple SSC model to all the hot spots and determine the ratio between the observed and predicted flux densities.…”

Section: Modeling and Resultsmentioning

confidence: 99%

“…The fact that a synchrotron model can be fitted through the radio, optical, and X-ray points in some high-R sources would have to be a coincidence in an SSC model, although this is a weak constraint; the optical emission might also be SSC, as it is thought to be in a couple of low-R sources (Hardcastle 2001;Brunetti 2002).…”

Section: þmentioning

confidence: 99%

The Origins of X‐Ray Emission from the Hot Spots of FR II Radio Sources

Hardcastle

Harris

Worrall

et al. 2004

ApJ

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174

224

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We use new and archival Chandra data to investigate the X-ray emission from a large sample of compact hot spots of FR II radio galaxies and quasars from the 3C catalog. We find that only the most luminous hot spots tend to be in good agreement with the predictions of a synchrotron self-Compton model with equipartition magnetic fields. At low hot spot luminosities inverse Compton predictions are routinely exceeded by several orders of magnitude, but this is never seen in more luminous hot spots. We argue that an additional synchrotron component of the X-ray emission is present in low-luminosity hot spots and that the hot spot luminosity controls the ability of a given hot spot to produce synchrotron X-rays, probably by determining the high-energy cutoff of the electron energy spectrum. It remains plausible that all hot spots are close to the equipartition condition.

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“…Specifically, the minimum Lorentz factor of this electron energy distribution is related to the luminosity as L rad ∝ γ min s−2 (Equation 8 of . The minimum Lorentz factor in the hotspot has been estimated by other authors for selected radio sources including: Cygnus A (McKean et al 2016), PKS 1421-490 (Godfrey et al 2009), 3C123, 3C196 and 3C295 (Hardcastle 2001). These hotspot Lorentz factor estimates are mostly in the order of a few hundred although these estimates are quite uncertain due to the confounding effects of free-free and synchrotron selfabsorption.…”

Section: Minimum Electron Lorentz Factormentioning

confidence: 99%

RAiSE III: 3C radio AGN energetics and composition

Turner

Shabala

Krause

2017

Monthly Notices of the Royal Astronomical Society

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Kinetic jet power estimates based exclusively on observed monochromatic radio luminosities are highly uncertain due to confounding variables and a lack of knowledge about some aspects of the physics of active galactic nuclei (AGNs). We propose a new methodology to calculate the jet powers of the largest, most powerful radio sources based on combinations of their size, lobe luminosity and shape of their radio spectrum; this approach avoids the uncertainties encountered by previous relationships. The outputs of our model are calibrated using hydrodynamical simulations and tested against independent X-ray inverse-Compton measurements. The jet powers and lobe magnetic field strengths of radio sources are found to be recovered using solely the lobe luminosity and spectral curvature, enabling the intrinsic properties of unresolved highredshift sources to be inferred. By contrast, the radio source ages cannot be estimated without knowledge of the lobe volumes. The monochromatic lobe luminosity alone is incapable of accurately estimating the jet power or source age without knowledge of the lobe magnetic field strength and size respectively. We find that, on average, the lobes of the 3C radio sources have magnetic field strengths approximately a factor three lower than the equipartition value, inconsistent with equal energy in the particles and the fields at the 5σ level. The particle content of 3C radio lobes is discussed in the context of complementary observations; we do not find evidence favouring an energetically-dominant proton population.

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An optical inverse-Compton hotspot in 3C 196?

Cited by 18 publications

References 19 publications

A Multiwavelength Study of the High Surface Brightness Hot Spot in PKS 1421–490

A Multiwavelength Study of the High Surface Brightness Hot Spot in PKS 1421–490

The Origins of X‐Ray Emission from the Hot Spots of FR II Radio Sources

RAiSE III: 3C radio AGN energetics and composition

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