Non-linear cosmic ray interaction with solar wind: Monitoring of flare energetic particle and solar wind matter space-time distributions by gamma rays Original Research Article

For great solar flare events we calculate expected gamma-ray fluxes in periods of flare energetic particle (FEP) generation and propagation. We calculate the expected space-time-energy distribution of these particles in the Heliosphere in the periods of FEP events. On the basis of investigations of cosmic ray non-linear interaction with solar wind we determine also the expected space-time distribution of solar wind matter. Then we calculate the expected generation of gamma rays by decay of neutral pions generated in nuclear interactions of FEP with solar wind matter and determine the expected space-time distribution of gamma ray emissivity. We based on the simplest model of FEP generation (source function is supposed proportional to delta function in time and in space) and the simplest model of propagation (isotropic diffusion). The aim of these rough calculations – to estimate approximately expected space-time distribution of gamma ray emissivity and then expected angle-time distribution of gamma ray fluxes during great FEP events in dependence of angle between direction of view and direction on the Sun, to answer on question: “Is it possible to monitor these fluxes by present-day gamma ray telescopes or not?”. Our calculations gave positive answer on this question. We note that the used simplest model of FEP propagation can be applied to observation data only 15–30 min after the onset of FEP event on the Earth when the FEP distribution became near isotropic. For the beginning stage when the FEP distribution is usually sufficiently anisotropic (and when the expected gamma ray fluxes are expected much bigger) necessary to use more complicated model of anisotropic diffusion. These results we suppose to present in near future. We hope that by observations of gamma rays generated by solar FEP interactions with solar wind matter can be obtained some additional information on FEP time generation and spectrum in the source, on mode of FEP propagation in the interplanetary space, on the character of the non-linear interaction of cosmic rays with solar wind, and on matter distribution in the Heliosphere.