LUCI+ARGOS image (K band; left) and HST image (Advanced Camera for Survey F814W filter; right, taken from Brusa et al. 2015a,b) of a region of ~6.5 × 6.5^″ around XID2028 (~ 55 × 55 kpc). In both panels, we show the contours from the LUCI+ARGOS data (black, arbitrary levels chosen to trace the whole K-band emission). The FWHM of the LUCI+ARGOS data is ~0.27^″ and shown in the lower right corner of the left panel. The emission from the host galaxy is clearly resolved. In the right panel, we also plot the contours of the ALMA continuum at 1.3 mm (rest-frame 500 μm; red solid curves, from the right panel of Fig. 1). North is up and east is left.