Stochastic particle acceleration in the lobes of giant radio galaxies
We investigate the acceleration of particles by Alfvén waves via the second-order Fermi process in the lobes of giant radio galaxies. Such sites are candidates for the accelerators of ultra-high-energy cosmic rays (UHECR). We focus on the nearby Fanaroff-Riley type I radio galaxy Centaurus A. This i...
| Main Authors: | , , |
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| Format: | Journal article |
| Language: | English |
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2009
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| _version_ | 1797095008500711424 |
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| author | O'Sullivan, S Reville, B Taylor, A |
| author_facet | O'Sullivan, S Reville, B Taylor, A |
| author_sort | O'Sullivan, S |
| collection | OXFORD |
| description | We investigate the acceleration of particles by Alfvén waves via the second-order Fermi process in the lobes of giant radio galaxies. Such sites are candidates for the accelerators of ultra-high-energy cosmic rays (UHECR). We focus on the nearby Fanaroff-Riley type I radio galaxy Centaurus A. This is motivated by the coincidence of its position with the arrival direction of several of the highest energy Auger events. The conditions necessary for consistency with the acceleration time-scales predicted by quasi-linear theory are reviewed. Test particle calculations are performed in fields which guarantee electric fields with no component parallel to the local magnetic field. The results of quasi-linear theory are, to an order of magnitude, found to be accurate at low turbulence levels for non-relativistic Alfvén waves and at both low and high turbulence levels in the mildly relativistic case. We conclude that for pure stochastic acceleration via Alfvén waves to be plausible as the generator of UHECR in Cen A, the baryon number density would need to be several orders of magnitude below currently held upper limits. © 2009 RAS. |
| first_indexed | 2024-03-07T04:21:52Z |
| format | Journal article |
| id | oxford-uuid:cb49b874-e249-48ec-9299-2ee5eebc35cf |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:21:52Z |
| publishDate | 2009 |
| record_format | dspace |
| spelling | oxford-uuid:cb49b874-e249-48ec-9299-2ee5eebc35cf2022-03-27T07:13:47ZStochastic particle acceleration in the lobes of giant radio galaxiesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:cb49b874-e249-48ec-9299-2ee5eebc35cfEnglishSymplectic Elements at Oxford2009O'Sullivan, SReville, BTaylor, AWe investigate the acceleration of particles by Alfvén waves via the second-order Fermi process in the lobes of giant radio galaxies. Such sites are candidates for the accelerators of ultra-high-energy cosmic rays (UHECR). We focus on the nearby Fanaroff-Riley type I radio galaxy Centaurus A. This is motivated by the coincidence of its position with the arrival direction of several of the highest energy Auger events. The conditions necessary for consistency with the acceleration time-scales predicted by quasi-linear theory are reviewed. Test particle calculations are performed in fields which guarantee electric fields with no component parallel to the local magnetic field. The results of quasi-linear theory are, to an order of magnitude, found to be accurate at low turbulence levels for non-relativistic Alfvén waves and at both low and high turbulence levels in the mildly relativistic case. We conclude that for pure stochastic acceleration via Alfvén waves to be plausible as the generator of UHECR in Cen A, the baryon number density would need to be several orders of magnitude below currently held upper limits. © 2009 RAS. |
| spellingShingle | O'Sullivan, S Reville, B Taylor, A Stochastic particle acceleration in the lobes of giant radio galaxies |
| title | Stochastic particle acceleration in the lobes of giant radio galaxies |
| title_full | Stochastic particle acceleration in the lobes of giant radio galaxies |
| title_fullStr | Stochastic particle acceleration in the lobes of giant radio galaxies |
| title_full_unstemmed | Stochastic particle acceleration in the lobes of giant radio galaxies |
| title_short | Stochastic particle acceleration in the lobes of giant radio galaxies |
| title_sort | stochastic particle acceleration in the lobes of giant radio galaxies |
| work_keys_str_mv | AT osullivans stochasticparticleaccelerationinthelobesofgiantradiogalaxies AT revilleb stochasticparticleaccelerationinthelobesofgiantradiogalaxies AT taylora stochasticparticleaccelerationinthelobesofgiantradiogalaxies |