Long-Term Monitoring of the Dynamics and Particle Acceleration of Knots in the Jet of Centaurus A

Goodger, J. L.; Hardcastle, M. J.; Croston, J. H.; Kraft, Ralph; Birkinshaw, Mark; Evans, D. A.; Jordán, Andrés; Nulsen, P. E. J.; Sivakoff, G. R.; Worrall, D. M.; Brassington, N. J.; Forman, W.; Gilfanov, M.; Jones, Christine; Murray, Stephen S.; Raychaudhury, Somak; Sarazin, Craig L.; Voss, R.; Woodley, Kristin A.

doi:10.1088/0004-637x/708/1/675

Cited by 55 publications

(95 citation statements)

References 51 publications

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“…Clarke et al (1992) found no evidence for internal depolarisation, so that only upper limits on the thermal electron densities can be inferred. For the knots for which we have sufficient constraints, A1A, A1B and A1C, using equipartition fields of 693, 323 and 763 μG (Goodger et al 2010), this gives upper limits of n e,th ∼ 3 × 10 −2 , ∼6 × 10 −3 and ∼8 × 10 −2 cm −3 , respectively. These are well above the densities that we estimate from entrainment.…”

Section: Constraints On Energy Density and Magnetic Fieldsmentioning

confidence: 99%

Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A

Wykes

Croston

Hardcastle

et al. 2013

A&A

127

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Observations of the FR I radio galaxy Centaurus A in radio, X-ray, and gamma-ray bands provide evidence for lepton acceleration up to several TeV and clues about hadron acceleration to tens of EeV. Synthesising the available observational constraints on the physical conditions and particle content in the jets, inner lobes and giant lobes of Centaurus A, we aim to evaluate its feasibility as an ultra-high-energy cosmic-ray source. We apply several methods of determining jet power and affirm the consistency of various power estimates of ∼1 × 10 43 erg s −1 . Employing scaling relations based on previous results for 3C 31, we estimate particle number densities in the jets, encompassing available radio through X-ray observations. Our model is compatible with the jets ingesting ∼3 × 10 21 g s −1 of matter via external entrainment from hot gas and ∼7 × 10 22 g s −1 via internal entrainment from jet-contained stars. This leads to an imbalance between the internal lobe pressure available from radiating particles and magnetic field, and our derived external pressure. Based on knowledge of the external environments of other FR I sources, we estimate the thermal pressure in the giant lobes as 1.5 × 10 −12 dyn cm −2 , from which we deduce a lower limit to the temperature of ∼1.6 × 10 8 K. Using dynamical and buoyancy arguments, we infer ∼440−645 Myr and ∼560 Myr as the sound-crossing and buoyancy ages of the giant lobes respectively, inconsistent with their spectral ages. We re-investigate the feasibility of particle acceleration via stochastic processes in the lobes, placing new constraints on the energetics and on turbulent input to the lobes. The same "very hot" temperatures that allow self-consistency between the entrainment calculations and the missing pressure also allow stochastic UHECR acceleration models to work.

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Section: Constraints On Energy Density and Magnetic Fieldsmentioning

confidence: 99%

Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A

Wykes

Croston

Hardcastle

et al. 2013

A&A

127

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“…These observations have allowed unprecedented insight into the X-ray jets (Hardcastle et al 2007;Worrall et al 2008;Goodger et al 2010), radio-lobe shock (Croston et al 2009), extended gaseous emission , and work on the XB, particularly in relation to globular clusters (Voss et al 2009, see also Woodley et al 2008 using pre-VLP data).…”

Section: Ngc 5128mentioning

confidence: 99%

A Transient Sub-Eddington Black Hole X-Ray Binary Candidate in the Dust Lanes of Centaurus A

Burke

Raychaudhury

Kraft

et al. 2012

ApJ

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We report the discovery of a bright X-ray transient CXOU J132527.6−430023 in the nearby early-type galaxy NGC 5128. The source was first detected over the course of five Chandra observations in 2007, reaching an unabsorbed outburst luminosity of (1-2) × 10 38 erg s −1 in the 0.5-7.0 keV band before returning to quiescence. Such luminosities are possible for both stellar-mass black hole and neutron star (NS) X-ray binary transients. Here, we attempt to characterize the nature of the compact object. No counterpart has been detected in the optical or radio sky, but the proximity of the source to the dust lanes allows for the possibility of an obscured companion. The brightness of the source after a >100-fold increase in X-ray flux makes it either the first confirmed transient non-ultraluminous X-ray black hole system in outburst to be subject to detailed spectral modeling outside the Local Group, or a bright (>10 38 erg s −1 ) transient NS X-ray binary, which are very rare. Such a large increase in flux would appear to lend weight to the view that this is a black hole transient. X-ray spectral fitting of an absorbed power law yielded unphysical photon indices, while the parameters of the best-fit absorbed disk blackbody model are typical of an accreting ∼10 M black hole in the thermally dominant state.

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“…This is much like the Centaurus A jet, but there the case for X-ray synchrotron emission is strong (e.g. Goodger et al 2010). The main issue for Cygnus A is that an active power source is required to maintain the population of highly relativistic electrons.…”

Section: X-ray Jetmentioning

confidence: 99%

Interaction of Cygnus A with its environment

Nulsen¹,

Young²,

Kraft³

et al. 2014

Proc. IAU

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Abstract. Cygnus A, the nearest truly powerful radio galaxy, resides at the centre of a massive galaxy cluster. Chandra X-ray observations reveal its cocoon shocks, radio lobe cavities and an X-ray jet, which are discussed here. It is argued that X-ray emission from the outer regions of the cocoon shocks is nonthermal. The X-ray jets are best interpreted as synchrotron emission, suggesting that they, rather than the radio jets, are the path of energy flow from the nucleus to the hotspots. In that case, a model shows that the jet flow is non-relativistic and carries in excess of one solar mass per year.

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Long-Term Monitoring of the Dynamics and Particle Acceleration of Knots in the Jet of Centaurus A

Cited by 55 publications

References 51 publications

Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A

Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A

A Transient Sub-Eddington Black Hole X-Ray Binary Candidate in the Dust Lanes of Centaurus A

Interaction of Cygnus A with its environment

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