Speaker
T. Bell
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/I1.001.pdf
Energetic particles in astrophysics and the laboratory
Tony Bell1,2
1
University of Oxford, UK
2
Rutherford Appleton Laboratory, UK
Particle acceleration is prevalent on all scales in the Universe, from the solar
system to clusters of galaxies. Energetic particles arrive at the Earth as cosmic
rays (CR) with energies ranging from GeV to EeV. Observations show that
acceleration to 100s of TeV takes place at the outer shocks of supernova remnants
(SNR). Diffusive shock acceleration (DSA) robustly produces cosmic rays at the
observed energies, with the observed energy spectrum, and with the required high
efficiency. Cosmic ray streaming excites plasma instabilities that drive MHD
turbulence, scatter the CR, confine the CR near the shock and mediate the
acceleration process. The instabilities also amplify the magnetic fields as
observed in SNR.
The origin of ultra-high energy cosmic rays (UHECR) at energies up to 100 EeV
is much less certain, although DSA on kpc scales in outflows from active galaxies
is a likely explanation.
Energetic particles are also a feature of laser-produced plasmas. Although the
scales differ by very many orders of magnitude, the underlying concepts are
surprisingly similar. Dedicated laboratory experiments have the potential to
validate and further clarify the plasma physics of astrophysical particle
acceleration.
