Redshift evolution of galaxy group X-ray properties in the SIMBA simulations

We examine the evolution of intragroup gas rest-frame X-ray scaling relations for group-sized haloes (M₅₀₀ = 10^12.3-10¹⁵ M_⊙) in the SIMBA galaxy formation simulation. X-ray luminosity L_X versus M₅₀₀ shows increasing deviation from self-similarity from z = 3 → 0, with M₅₀₀ < 10^13.5 M_⊙ haloes exhibiting a large reduction in L_X and slight increase in X-ray luminosity-weighted temperature T_X. These shifts are driven by a strong drop in f_gas with time for these haloes, and coincides with the onset of SIMBA's black hole (BH) jet feedback, occurring when M_BH > 10^7.5 M_⊙ and Eddington ratio <0.2, in group haloes at z ~ 1.5. The connection with BH feedback is corroborated by f_BH ≡ M_BH/M₅₀₀ in M₅₀₀ < 10^13.5 M_⊙ haloes being strongly anticorrelated with L_X and f_gas at $z\lesssim 1.5$. This is further reflected in the scatter of L_X - T_X: haloes with small f_BH lie near self-similarity, while those with the highest f_BH lie furthest below. Turning off jet feedback results in mostly self-similar behaviour down to z = 0. For the X-ray weighted metallicity Z_X, stellar feedback impacts the enrichment of halo gas. Finally, halo profiles show that jet feedback flattens the electron density and entropy profiles, and introduces a core in X-ray surface brightness, particularly at M₅₀₀ < 10^13.5 M_⊙. This argues that in SIMBA, intragroup X-ray evolution is largely driven by jet feedback removing hot gas from the cores of massive groups, and expelling gas altogether in less massive groups.