Si IV 1394 Å Gaussian parameters and selected spectra from jet. Panels a–c: single-Gaussian (SG) parameter maps for peak intensity [DN], Doppler velocity [km s⁻¹], and full-width at half maximum (FWHM) [km s⁻¹] for Si IV, respectively. The colored diamonds mark the three individual pixels whose spectral profiles are shown in the bottom two rows, while the gold square marks, for reference, a fourth pixel whose spectrum is shown in Fig. 5. Panels d–f: individual pixels’ spectra in gray [DN] with the SG fitted curve overlaid in black. The Doppler velocity (Vel) and non-thermal width (ξ) are listed in the upper left. Panels g–i: same three spectra, except a double-Gaussian (DG) fitted curve is overlaid in black and its two components are drawn in red (primary component) and blue (secondary component). The primary and secondary Doppler velocities (Vel1, Vel2) and non-thermal widths (ξ1, ξ2) are listed in the upper left. For all panels d–i, a vertical black line in the center marks the location of zero-velocity, for reference. See Sects. 3.1 and 4.2.