| Summary: | 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 Δ t _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 ^8.6 M _⊙ ) and MACS0417-z5BBG ( z = 5.2, M _⋆ = 10 ^7.6 M _⊙ ) 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.
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