We build upon FEGA25, a previously introduced semianalytic model (SAM) for galaxy formation and evolution, by focusing on its enhanced treatment of supernova (SN) and active galactic nucleus (AGN) feedback mechanisms. In addition to the traditional AGN feedback mode—negative (suppressing cooling) and the new positive mode (triggering star formation)—we introduce two distinct implementations of a third mode: the ejection of hot gas beyond the virial radius (AGNeject1 and AGNeject2). This component addresses a longstanding issue in SAMs and hydrodynamical simulations: the overestimation of hot gas fractions in low- and intermediate-mass halos. FEGA25 is calibrated via Markov Chain Monte Carlo using a suite of cosmological N-body simulations (YS50HR, YS200, YS300) and a comprehensive set of observed stellar mass functions across a wide redshift range. We find that SN feedback dominates gas ejection in halos with , while AGN feedback becomes increasingly important at higher halo masses. The AGNeject2 model, which activates primarily at late times (z < 1), reproduces a characteristic, roughly U-shaped, “cavity” in the baryon fraction at z = 0, similar to trends observed in simulations like SIMBA and IllustrisTNG. Conversely, AGNeject1 yields a smoother, redshift-independent evolution. Both models preserve the stellar and cold-gas components and successfully reproduce the stellar-to-halo mass relation up to z = 3. Our results emphasize that a physically motivated AGN-driven mechanism capable of selectively removing hot gas is essential to model the baryon cycle accurately, particularly in the intermediate-halo-mass regime.

NASA/ADS