86 GHz continuum (black contour with levels starting from 3 mJy beam⁻¹ in steps of 1 mJy beam⁻¹), a velocity integrated map of H¹³CN 1−0 (grey scale, in units of Jy km s⁻¹ beam⁻¹), a velocity integrated map of HCN 1−0 red wing (red contour with levels starting from 0.2 Jy km s⁻¹ beam⁻¹ in steps of 0.05 Jy km s⁻¹ beam⁻¹) and a velocity integrated map of HCN 1−0 blue wing (blue contour with levels starting from 0.2 Jy km s⁻¹ beam⁻¹ in steps of 0.05 Jy km s⁻¹ beam⁻¹), around the centre of Arp 220 west. The dashed cyan boxes are the regions for the spectra in Figs. 2 and 3. The restoring beam (0.151″ × 0.109″, PA = 23.4°) of the data cube is shown in the bottom left. The central coordinates of this map are RA: 15:34:57.22 and Dec: 23:30:11.6 (J2000).