Emission line maps and spectra of TN J0121+1320 showing evidence of [C II] companion detection. (a): [C II] moment 0 maps in contours integrated at different channels as indicated in the bottom right corner. The contours are given in [3, 4, 5, …] × σ levels, where σ is the rms noise of the map. We note that only odd σ levels are used for [C II]-B for better visualization. The gray scale background image is the same as Fig. 1b. The red open crosses mark the positions of the [C II] companions, i.e., the same as the red boxes in Fig. 1. (b): [C II] spectra extracted at the [C II] companion positions. The vertical shaded regions mark the velocity ranges where the moment 0 maps in panel (a) are integrated. The single Gaussian fit of [C II] spectra are shown as dark magenta curves. Where available, we show the [O III]5007 spectra in black in arbitrary units extracted at the same position with the same aperture as the [C II] companion. We mark the projected distance between the [C II] and the radio core at the top right corners.