Solar energetic electron transport across the heliospheric current sheet - A statistical study

Solar eruptive events such as flares and coronal mass ejection (CME)-driven shocks can release solar energetic particles (SEPs) into the heliosphere. The heliospheric current sheet (HCS) is a large-scale structure that separates regions of opposite magnetic polarity. Its influence on SEP propagation remains poorly understood. In this study, we analysed SEE events in the Comprehensive Solar Energetic Electron event Catalogue (CoSEE-Cat) and classified them into two groups: same-side events, where both the solar source and spacecraft are in the same magnetic sector, and opposite-side events. The magnetic polarities of the solar source region and the spacecraft location are determined comprehensively using approaches based on the potential field source surface (PFSS), magnetic field measurements, the pitch angle distribution of strahl electrons, and the first-order anisotropy of energetic electrons. The uncertainties in determining magnetic polarities associated with these methods are evaluated. The spacecraft magnetic polarities determined by footpoint positions at the source surface and in situ observations are consistent for most events, providing a useful methodological reference for future studies. We identified 60 same-side events and 9 opposite-side events. By comparing characteristics of events in these two groups, we were able to investigate the potential influence of the HCS on SEP propagation. Our results show that opposite-side events tend to be more isotropic and that both the solar source and the spacecraft are closer to the HCS than in same-side events. This suggests that particle transport across the HCS is inefficient unless the source or the observer is close to the HCS. These preliminary statistical findings advance our understanding of the role of the HCS in shaping SEP transport.