Trends and issues in energy supply and demand in the Midwest

Cavallo, J.D.

doi:10.2172/6198857

Cited by 2 publications

(3 citation statements)

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“…Cavallo 1978). Junkes et al (1993) alluded to the possibility that the chaotic behaviour of polarisation associated with the southern giant lobe of Cen A may well be due to internal turbulence, and Feain et al (2009) found a depolarised signal and RM fluctuations intrinsic to the southern giant lobe of Cen A that they ascribe to turbulent magnetised plasma inside the lobe.…”

Section: Turbulence and Alfvénic Accelerationmentioning

confidence: 99%

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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: Turbulence and Alfvénic Accelerationmentioning

confidence: 99%

“…Cavallo 1978;Biermann & Strittmatter 1987;Stecker et al 1991;Mannheim 1995;Benford & Protheroe 2008;Hardcastle et al 2009;Kachelrieß et al 2009;Hardcastle 2010;Pe'er & Loeb 2012). The synchrotron and inverse-Compton emission from these structures is seen in all wavebands from low-frequency radio to TeV gamma-ray.…”

Section: Introductionmentioning

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

View full text Add to dashboard Cite

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“…These radio lobes, along with Cen A's proximity to the Milky Way, have long made Cen A a prime prospective source of UHECR (Cavallo 1978;Romero et al 1996;Ahn et al 1999;Farrar & Piran 2000;Isola et al 2002). This is in stark contrast to the lack of an excess toward the Virgo galaxy cluster, home of the powerful AGN M87.…”

Section: Introductionmentioning

confidence: 99%

The Centaurus a Ultrahigh-Energy Cosmic-Ray Excess and the Local Extragalactic Magnetic Field

Yüksel

Stanev

Kistler

et al. 2012

ApJ

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The ultrahigh-energy cosmic-ray (UHECR) anisotropies discovered by the Pierre Auger Observatory provide the potential to finally address both the particle origins and properties of the nearby extragalactic magnetic field (EGMF). We examine the implications of the excess of ∼10 20 eV events around the nearby radio galaxy Centaurus A. We find that, if Cen A is the source of these cosmic rays, the angular distribution of events constrains the EGMF strength within several Mpc of the Milky Way to 20 nG for an assumed primary proton composition. Our conclusions suggest that either the observed excess is a statistical anomaly or the local EGMF is stronger than conventionally thought. We discuss several implications, including UHECR scattering from more distant sources, time delays from transient sources, and the possibility of using magnetic lensing signatures to attain tighter constraints.

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Trends and issues in energy supply and demand in the Midwest

Cited by 2 publications

References 0 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

The Centaurus a Ultrahigh-Energy Cosmic-Ray Excess and the Local Extragalactic Magnetic Field

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