Signals at ground level of relativistic solar particles associated to the "All Saints" filament eruption on 2014

TL;DR

This study reports ground-level detections of relativistic solar particles linked to a solar filament eruption and CME, highlighting complex particle propagation mechanisms beyond simple perpendicular diffusion.

Contribution

It provides new insights into the ground-level signatures of solar energetic particles associated with a specific filament eruption and explores the propagation processes involved.

Findings

Detection of muon enhancement at ground level coinciding with SEP onset.

Observation of increased particle intensity at South Pole neutron monitor.

Evidence suggesting combined propagation processes, including high CME shock speeds.

Abstract

Far away from any sunspot, a bright flare erupted on November 1st, 2014, with onset at 4:44 UT and a duration of around three hours, causing a C2.7-class flare. The blast was associated with the sudden disappearance of a large dark solar filament. The rest of the filament flew out into space, forming the core of a massive CME. Despite the location of the explosion over the sun's southeastern region (near the eastern edge of the sun) not be geoeffective, a radiation storm, that is, solar energetic particles (SEP) started to reach the Earth around 14:00 UT, reaching the condition of an S1 (minor) radiation storm level on Nov. 2th. In coincidence with onset of the S1 radiation storm (SEP above 5 MeV), the Tupi telescopes located at $22^090'$S; $43^020'$W, within the South Atlantic Anomaly (SAA) detected a muon enhancement caused by relativistic protons from this solar blast. In addition an increase in the particle intensity was found also at South Pole neutron monitor. This means that there was a transverse propagation to the interplanetary magnetic field of energetic solar particles. However, we show that perpendicular diffusion alone cannot explain these observations, it is necessary a combination with further processes as a very high speed, at least of a fraction the CME shocks, close to the ecliptic plane.