Models for the Arp 220 western nucleus in 13CO J = 4–3 (orange lines) shown along with the observed line profiles at half-beam increments along the disk axis and perpendicular to the disk axis. The column density of the model in the central position is 4.9 × 1025 H2 cm−2. Moving either to the left or right one panel at a time, the models’ column density decreases to 1.1 × 1025 H2 cm−2, 1.5 × 1024 H2 cm−2, and 2.0 × 1023 H2 cm−2. Likewise, moving one panel at time in the vertical direction, the column density decreases to 9.5 × 1024 H2 cm−2 and 1.1 × 1024 H2 cm−2. 1 Jy/beam = 294.5 K. An interactive figure is available.
An interactive version of this figure is available in the online journal.