2024ApJ...964...76G

JWST is providing a unique opportunity to directly study the feedback processes regulating star formation (SF) in early galaxies. The two z > 5 quiescent systems (JADES-GS-z7-01-QU and MACS0417-z5BBG) detected so far show a recent starburst after which SF is suppressed. To clarify whether such quenching is due to supernova (SN) feedback, we have developed a minimal physical model. We derive a condition on the minimum star formation rate, ${\mathrm{SFR}}_{\min }$, lasting for a time interval Δt_b, required to quench SF in a galaxy at redshift z, with gas metallicity Z, and hosted by a halo of mass M_h. We find that lower (z, Z, M_h) systems are more easily quenched. We then apply the condition to JADES-GS-z7-01-QU (z = 7.3, M_⋆ = 10^8.6M_⊙) and MACS0417-z5BBG (z = 5.2, M_⋆ = 10^7.6M_⊙) and find that SN feedback largely fails to reproduce the observed quenched SF history. Alternatively, we suggest that SF is rapidly suppressed by radiation-driven dusty outflows sustained by the high specific star formation rates (43 and 25 Gyr^–1, respectively) of the two galaxies. Our model provides a simple tool to interpret the SF histories of post-starburst galaxies and unravel quenching mechanisms from incoming JWST data.