Maps of T_ex for (a) atomic carbon and (c) mid-J CO. Contours represent the ¹³CO J = 5−4 emission from 10⁻⁹ W m⁻² sr⁻¹ (gray) to 2.8 × 10⁻⁸ W m⁻² sr⁻¹ (magenta) tracing high N(H₂) regions. (b) Line surface brightness ¹²CO / ¹³CO J = 5−4 ratio map. (d) Population diagrams of ¹²CO lines observed with SPIRE-FTS toward positions A, B, C, and D in Sgr B2 (see Table 4). Dashed curves refer to fits to positions A and D.