2019/07/31 by Xiangliang Kong, Fan Guo, Yao Chen +1 · 26 citations
Physics and Astronomy · #Acceleration #Astrophysics and Cosmic Phenomena #Diffusion #Ionosphere and magnetosphere dynamics #Magnetic field #Particle (ecology) #Particle acceleration #Shock (circulatory) #Shock wave #Solar and Space Plasma Dynamics #Solar energetic particles #Spectral line #astro-ph.SR #physics.space-ph
paper · pdf · doi:10.3847/1538-4357/ab3848
published in The Astrophysical Journal 883(1), 49 (IOP Publishing)
arxiv created 2019/07/31 · openalex created_date 2019/08/13 · openalex publication_date 2019/09/19 · arxiv updated 2019/09/25 · openalex updated_date 2026/08/06
Abstract We present numerical modeling of particle acceleration at coronal shocks propagating through a streamer-like magnetic field by solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show that the location on the shock where the high-energy particle intensity is the largest, depends on the energy of the particles and on time. The acceleration of particles to more than 100 MeV mainly occurs in the shock-streamer interaction region, due to perpendicular shock geometry and the trapping effect of closed magnetic fields. A comparison of the particle spectra to that in a radial magnetic field shows that the intensity at 100 MeV (200 MeV) is enhanced by more than one order (two orders) of magnitude. This indicates that the streamer-like magnetic field can be an important factor in producing large solar energetic particle events. We also show that the energy spectrum integrated over the simulation domain consists of two different power laws. Further analysis suggests that it may be a mixture of two distinct populations accelerated in the streamer and open field regions, where the acceleration rate differs substantially. Our calculations also show that the particle spectra are affected considerably by a number of parameters, such as the streamer tilt angle, particle spatial diffusion coefficient, and shock compression ratio. While the low-energy spectra agree well with standard diffusive shock acceleration theory, the break energy ranges from ∼1 MeV to ∼90 MeV and the high-energy spectra can extend to ∼1 GeV with a slope of ∼2–3.