Schematic drawing of the spatial arrangement and morphology of the different structural components in our representation of the interstellar gas, a) in the plane of the sky; b) looking along the α-axis from west to east; and c) looking along the δ-axis from north to south. Shaded in blue are the diffuse, mostly ionized components, which include the central cavity (CC), the Sgr A East SNR and the radio halo. Shaded in red are the denser, mostly molecular components, which include the circumnuclear ring (CNR), the southern cloud M − 0.13 − 0.08 (SC), also known as the 20   km   s^-1 cloud, the eastern cloud M − 0.02 − 0.07 (EC), also known as the 50   km   s^-1 cloud, the molecular ridge (MR), the southern streamer (SS), the western streamer (WS) and the northern ridge (NR). The position of Sgr A^∗ is indicated with a plus sign at the center of each panel. In the side and top views, the line-of-sight coordinate of the center of M − 0.13 − 0.08 (our only free parameter) is set to x_SC = 8 pc, which is right in the middle of the allowed range.