1999/06/01 by R. D. Blandford · 99 citations
Physics and Astronomy · #Acceleration #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmic microwave background #Cosmic ray #Dark Matter and Cosmic Phenomena #Galaxy #Gamma-ray burst #Gamma-ray bursts and supernovae #Luminosity #Optics #Particle acceleration #Physics #Ultra-high-energy cosmic ray #astro-ph
paper · pdf · doi:10.1238/physica.topical.085a00191
published in Physica Scripta T85(1), 191 (IOP Publishing) · 11pp. To appear in Particle Physics and the Universe. Ed. Bergstrom, Carlson and Fransson. Physica Scripta World Scientific
arxiv created 1999/06/01 · openalex publication_date 2000/01/01 · arxiv updated 2010/12/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Some general features of cosmic ray acceleration are summarized along with some inferences that can be drawn concerning the origin of the UHE component. The UHE luminosity density is found to be similar to that derived for GeV cosmic rays and its slope suggests a distinct origin. Reports of clustering on small angular scale, if confirmed, would rule out most proposed source models. More generally, it is argued that the highest energy particles can only be accelerated in sites that can induce an EMF cal E go3\×1020 V and an associated power Lmin go cal E2/Z\∼1039 W, where Z is the characteristic, electrical impedance, typically lo100\Ω. Shock acceleration, unipolar induction and magnetic flares are the three most potent, observed, acceleration mechanisms and radio jet termination shocks, are the least implausible, ``conventional'' manifestations of these mechanisms that have been invoked to explain the UHE cosmic rays. Each of these models presents problems and deciding between these and ``exotic'' origins for UHE cosmic rays, including those involving new particles or defects will require improved statistical information on the energies, arrival times and directions, as should be provided by the Auger project.