Spectrum of the emission at various times for model M2. The top panel shows the result of a run without particle escape, and emission from the PWN is displayed at 1000, 8000, and 19 000 yr (the latter two corresponding to reverse-shock crushing and first re-expansion, respectively). The bottom panel shows the result of a run including particle escape, and emission from the PWN, SNR, and CSM components is displayed at 1000, 9000, and 20 000 yr (the latter two still corresponding to reverse-shock crushing and first re-expansion).