Fig. 4

The energy spectra of electron PSD_⊥ observed inside and outside the ESMC. PSD_⊥ is averaged over 360° in the plane perpendicular to the magnetic field. In panel a, the x-axis is the electron energy, and the y-axis is the average PSD_⊥ (with error bars). The red line represents observations taken near the center of the ESMC, and the other two lines (blue and green) represent observations outside the structure. The time of measurement and the distance between the spacecraft and the center of ESMC are labeled in the top right corner. In panel b, the x-axis is the same as that in panel a, but the energy is reformulated in terms of electron gyro-radius ρ and normalized by the gyro-radius of the thermal electron (ρ_e) or the radius of the magnetic cavity (R_MC). γ is the ratio between the PSD_⊥ inside (red line in panel a) and outside (blue and green lines in panel a) the structure in each energy channel. The error bars in panel a are instrumental errors directly obtained from the FPI data product