Cake Talk by Viola Gelli
The surprising JWST discovery of a quiescent, low-mass (log M*/Msun = 8.7) galaxy at redshift z = 7.3 (JADES-GS-z7-01-QU) represents a unique opportunity to study the imprint of feedback processes on early galaxy evolution. We build a sample of 130 low-mass (log M*/Msun < 9.5) galaxies from the SERRA cosmological zoom-in simulations, which show a feedback-regulated, bursty star formation history (SFH). The fraction of time spent in an active phase increases with the stellar mass from f_duty~0.6 at log M*/Msun = 7.5 to ~0.99 at logM*/Msun > 9, and it is in agreement with the value f_duty~0.75 estimated for JADES-GS-z7-01-QU. On average, 30% of the galaxies are quiescent in the range 6 < z < 8.4; they become the dominant population at log M*/Msun < 8.3. However, none of these quiescent systems matches the Spectral Energy Distribution of JADES-GS-z7-01-QU, unless their SFH is artificially truncated a few Myr after the main star formation peak. As supernova feedback can only act on a longer timescale (>30 Myr), this implies that the observed abrupt quenching must be caused by a faster physical mechanism, such as radiation-driven winds from young massive stars and/or AGN.