Mg II S/N map as constructed in Sect. 4.1 and smoothed using a 1, 2, 3, 4, 5, and 6 spaxel FWHM Gaussian from left to right, respectively. The FWHM values are indicated and shown as white circle (top right) in each panel. For comparison, the FWHM of the MUSE PSF is shown with a hatched white circle. The solid, dashed and dotted black contours correspond to a S/N of 1.5, 2 and 3, respectively. The adopted smoothing kernel has a FWHM of (i.e., 3 spaxels or ≈5 kpc at z = 1.31) and allows us to improve the S/N while keeping a good spatial resolution.