Onset time of the GLE 72 observed at neutron monitors and its relation to electromagnetic emissionsстатья
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Дата последнего поиска статьи во внешних источниках: 1 августа 2019 г.
Аннотация:We present an overview of the ground level enhancement (GLE 72) of cosmic ray intensity associated with the recent powerful solar flare SOL2017-09-10 (X8.9) based on the available neutron monitor (NM) network observations and on data from the satellite GOES 13. Maximum increase on high latitude near sea-level NMs was ~6-7% (2 min averages), higher in better time resolution). Scatter plot of maximum increase of GLE versus SPE proton flux > 100 MeV shows one of the softest spectra among GLEs relative to the SPE fluxes. However, at two high mountain middle latitude NMs the increase was ~ 1% indicating possibility of proton acceleration up to 6 GeV. Among the analyzed NM data Fort Smith (FSMT) NM shows the earliest and rather high increase between 16:06-16:08 UT. This indicates the anisotropy in the first phase of the GLE event. We calculated the acceptance cones of several NM stations at high latitudes and contours of pitch angles corresponding to IMF. We found that pion-decay gamma – ray emission onset was in accordance with the time of the main flare energy release. The observed time interval of the impulsive burst of >100 MeV gamma–ray emission probably corresponds to the time of the turbulent current sheet creation. It seems that models assuming sub-relativistic proton production beginning in the turbulent reconnecting current sheet are consistent with the observations. If these particles released from the Sun in time interval of Type III emission and pion-decay maximum at 16:00:30±30 s UT, we get a plausible path length equal to 1.5±0.3 AU of the particles responsible for the onset of the SPE/GLE. The time lag of GLE 72 is located within the most probable interval of time difference between GLE onset and the main flare energy release. We attribute the protons which created pion-decay emission and the protons responsible for the GLE/SPE onset with one general population of accelerated particles.