Spatially resolved Mg II and [O II] properties. Left: binned line-of-sight velocity maps of the Mg II (top) and [O II] (bottom) emission relative to the systemic redshift of galaxy A (Sects. 4.4 and 5.1). The black contours correspond to the 1.5σ significance level. The green contours trace the galaxies detected in the HST/ACS F775W image. The FWHM of the MUSE PSF and smoothing kernel are shown with a hatched and an empty circle, respectively, at the top right of the panels. The diverging Mg II and [O II] colormaps are centered on the systemic redshift of galaxy A and have the same dynamical range to ease the visual comparison (Sect. 5.1). Right: Mg II (top) and [O II] (bottom panels) doublet extracted in the elliptical areas traced in purple and designated by the same number on the map (left panels). The vertical dashed lines correspond to the systemic redshift of galaxy A. The vertical hatched bands indicate the presence of sky lines.