We examine X-ray scaling relations for massive halos (M500 > 1012.3M⊙) in the Simba galaxy formation simulation. The X-ray luminosity , LX vs. M500 has power-law slopes $\approx \frac{5}{3}$ and $\approx \frac{8}{3}$ above and below 1013.5M⊙, deviating from the self-similarity increasingly to low masses. TX − M500 is self-similar above this mass, and slightly shallower below it. Comparing Simba to observed TX scalings, we find that LX, LX-weighted [Fe/H], and entropies at 0.1R200 (S0.1) and R500 (S500) all match reasonably well. S500 − TX is consistent with self-similar expectations, but S0.1 − TX is shallower at lower TX, suggesting the dominant form of heating moves from gravitational shocks in the outskirts to non-gravitational feedback in the cores of smaller groups. Simba matches observations of LX versus central galaxy stellar mass M*, predicting the additional trend that star-forming galaxies have higher LX(M*). Electron density profiles for M500 > 1014M⊙ halos show a ∼0.1R200 core, but the core is larger at lower masses. TX are reasonably matched to observations, but entropy profiles are are too flat versus observations for intermediate-mass halos, with Score ≈ 200 − 400 keV cm2. Simba’s [Fe/H] profile matches observations in the core but over-enriches larger radii. We demonstrate that Simba’s bipolar jet AGN feedback is most responsible for increasingly evacuating lower-mass halos, but the profile comparisons suggest this may be too drastic in the inner regions.

We examine the evolution of intragroup gas X-ray scaling relations for group-sized halos (M 500 = 10 12.3−15 M ) in the Simba galaxy formation simulation. X-ray luminosity L X vs M 500 shows increasing deviation from self-similarity from z = 3 → 0, with M 500 < 10 13.5 M halos exhibiting a large reduction in L X and slight increase in X-ray luminosityweighted temperature T X . These shifts are driven by a strong drop in f gas with time for these halos, and coincides with the onset of black hole jet feedback in these systems at z ∼ 1.5 in Simba. The connection with black hole feedback is corroborated by f BH ≡ M BH /M 500 in M 500 < 10 13.5 M halos being strongly anti-correlated with L X and f gas at z < ∼ 1.5. This is further reflected in the scatter of L X − T X : halos 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 M 500 < 10 13.5 M . This argues that 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.

We examine the evolution of intragroup gas rest-frame X-ray scaling relations for group-sized halos (M500 = 1012.3 − 15M⊙) in the Simba galaxy formation simulation. X-ray luminosity LX vs M500 shows increasing deviation from self-similarity from z = 3 → 0, with M500 &lt; 1013.5M⊙ halos exhibiting a large reduction in LX and slight increase in X-ray luminosity-weighted temperature TX. These shifts are driven by a strong drop in fgas with time for these halos, and coincides with the onset of Simba’s black hole jet feedback, occurring when MBH &gt; 107.5M⊙ and Eddington ratio &lt;0.2, in group halos at z ∼ 1.5. The connection with black hole feedback is corroborated by fBH ≡ MBH/M500 in M500 &lt; 1013.5M⊙ halos being strongly anti-correlated with LX and fgas at $z\lesss00000im 1.5$. This is further reflected in the scatter of LX − TX: halos with small fBH lie near self-similarity, while those with the highest fBH lie furthest below. Turning off jet feedback results in mostly self-similar behaviour down to z = 0. For the X-ray weighted metallicity ZX, 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 &lt; 1013.5M⊙. 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.