Solar Energetic Electron Events on 2022 December 24

We investigate two adjacent solar energetic electron (SEE) events measured by Solar Orbiter/EPD at 0.93 au with a separation of ~30 minutes on December 24, 2022. STEREO-A (Wind) with a longitudinal separation of ~5°(19°) from Solar Orbiter shows no clear observations of SEEs, indicating the presence of a <20° longitudinal distribution for these two events. In addition, the nearly symmetric peaks in temporal profiles and strongly beamed pitch angle distributions in both events suggest that most of these SEEs undergo essentially scatter-free propagation in the interplanetary medium. Utilizing the pan-spectrum fitting method, we self-consistently determine the spectral shape of background-subtracted electron peak flux vs energy. Event #1 is fitted to a triple power-law spectrum with two spectral breaks at ~22 and 290 keV. Event #2 shows a double power-law spectrum with a spectral break around 25 keV. For both events, the power-law spectrum extends down to below 10 keV, implying that these SEEs could originate high in the corona. We further derive the electron injection profiles at sun by forward fitting in-situ temporal profiles, for the two events. According to the characteristics of injection timing and spectral shape, Event #1 consists of three SEE populations, respectively, at energies below ~22 keV, between ~22 keV and ~290 keV, and above ~290 keV, while Event #2 consists of two populations, respectively, at energies below and above ~25 keV. The low-energy population likely provides seed populations for further acceleration process (processes) to form the high-energy population (populations).