Resolving multiple sources of solar relativistic particles

Abstract

We consider the time-profile morphology of solar high-energy particle emissions, including relativistic electrons in three energy channels of SOHO/EPHIN, relativistic protons as registered by the worldwide network of neutron monitors, and ∼ 100 MeV/n protons and helium in several energy channels of SOHO/ERNE. Based on numerical modeling of the interplanetary transport, we formulate a simple method for investigation of the high-energy particle sources operating at / near the Sun during the first hour of particle event. The method is applied to Ground Level Enhancement (GLE) and Solar Energetic Particle (SEP) events of the solar cycle 23. We conclude that depending on the GLE-SEP event scenario and detector vantage point, the observed particles originate from at least three sources. Possible nature of the sources is discussed in the framework of previous and new models of the high-energy particle production associated with global coronal (EIT) waves and CME shocks within about five solar radii from the Sun. PoS(ICRC2015)057GLE origins Leon Kocharov Method and resultsWe start with modeling of the SEP transport from a source near the Sun to a detector at 1 AU. Interplanetary propagation of high-energy particles is modeled in the framework of focused transport [1] for the Kolmogorov turbulence spectrum in the standard solar wind. The energy dependence of the proton mean free path is according to the standard quasi-linear theory, while the mean free path of ≈ 1 MeV electrons is equal to that of the 1 MeV protons [2]. For analysis of real events, we simulate particle transport and registration with actual energy spectra, energy channels, aperture and viewing direction of a particular instrument. At large values of the mean free path, λ 3 AU, the particle source profile may be estimated by a proper shifting of the instrument's counting rate profile back in time. The mean free path value is estimated using the flux anisotropy measurements.Based on the results of particle transport and registration modeling, we shift the observed time-intensity profiles in time back to the Sun but add eight minutes to facilitate a comparison with electromagnetic emissions observed at 1 AU: t S = t − ∆t + 8 min. The time-shifted and renormalised profiles of the 13 December 2006 event (GLE 70) are shown in Figure 1. Plotted only the neutron monitor profile revealing the earliest and steepest onset in this GLE. For a convenience of comparison of different particle species and energy channels, the background levels are reduced to one and the same level that is 1% of the real neutron monitor background.