Multi-spacecraft Observations of Interplanetary Suprathermal Electrons in a Shock-ICME Interaction Region

Multiple interplanetary coronal mass ejections (ICMEs) and the shocks they drive sometimes form shock-ICME interaction regions, where suprathermal electrons can undergo complex and not yet fully understood physical processes. To enhance our understanding of electron acceleration and transportation in these regions, we will present a comprehensive study of a shock-ICME interaction case based on multi-spacecraft observations. From November 29th to December 2nd, 2023, four ICMEs and three ICME-driven shocks were successively observed by SolO (0.84 AU), STEREO-A (0.97 AU), and Wind (0.99 AU), with a maximum longitudinal separation of ~17°. First, we will analyze the electron pitch angle distributions to constrain scattering and/or reflection effects at each location. Secondly, we will self-consistently characterize the energy spectral features of these suprathermal electrons using a recently proposed extended pan-spectrum fitting method (Li et al., 2025). These features will help reveal the origin, acceleration, and transportation processes of suprathermal electrons observed in shock-ICME interaction regions, particularly the different physical scenarios occurring at each interaction phase. Finally, we will compare these suprathermal electrons with those observed near typical interplanetary shocks, in order to assess whether shock-ICME interaction regions provide more efficient acceleration for suprathermal electrons.