Scenario (1) – quenched star formation model. Top panel: log ratio of the 144 MHz to FUV emission (blue) and Hα emission (orange) for a quenching time of 50 Myr (solid lines), 100 Myr (dashed lines), and 200 Myr (dotted lines) as a function of the time since the onset of SFR quenching. The ratios are relative to t = 0. Bottom panel: evolution of the 144 MHz to 1.4 GHz spectral index for the two models.