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public:seminar_abstracts [2018/10/29 15:55]
Krishna Prasad
public:seminar_abstracts [2018/10/30 15:31] (current)
Mark Magee
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 ====== ARC Seminar Abstracts ====== ====== ARC Seminar Abstracts ======
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 +===The origin of the highest energy particles in the universe: A "​Whodunnit"​ =====
 +** Dr James Matthews** (Oxford)- ARC Seminar Wednesday 7 November 2018 1pm
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 +The origin of ultra-high energy cosmic rays (UHECRs) - protons and nuclei striking our atmosphere with energies extending beyond 1e20 eV - has been an open question for decades. In this talk I will review what we know about UHECRs from an observational and theoretical perspective,​ focusing particularly on diffusive shock acceleration. I will discuss the physical requirements for acceleration,​ before exploring whether radio galaxies might meet these requirements. Aided by hydrodynamic simulations,​ I will show that shocks can be formed in backflows in the radio lobe and that these shocks are better accelerators to ultra-high energies than the relativistic termination shock. I will then discuss a model in which giant-lobed radio galaxies such as Centaurus A and Fornax A act as slowly-leaking UHECR reservoirs, with the UHECRs being accelerated during a more powerful past episode. These radio galaxies may also explain the observed hotspots in the UHECR data, but deflections in Galactic and extragalactic magnetic fields make robust associations difficult. ​
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 ===A Nanoflare Explanation for Periodic Variations in Flare Stars  --  A Solar Physicist'​s Adventure in Single Pixel Land ===== ===A Nanoflare Explanation for Periodic Variations in Flare Stars  --  A Solar Physicist'​s Adventure in Single Pixel Land =====
public/seminar_abstracts.txt · Last modified: 2018/10/30 15:31 by Mark Magee

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