Brightness per velocity channel in the QSO. Color-coded values and contours at [2, 3, 5] σ levels are shown. The numbers in the upper right corners of the panels denote the central velocity of the channel. The filled circle represents the peak of the integrated surface brightness of the quasar, while the cross represents the peak of the surface brightness of the faint companion, which is detected in channels ~  − 362: − 242 km s^-1.