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 \sim 1 \times 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 \sim 3 \times 10 ^ { 21 } g s ^ { -1 } of matter via external entrainment from hot gas and \sim 7 \times 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 \times 10 ^ { -12 } dyn cm ^ { -2 } , from which we deduce a lower limit to the temperature of \sim 1.6 \times 10 ^ { 8 } K. Using dynamical and buoyancy arguments , we infer \sim 440 - 645 Myr and \sim 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 .