A systematic study of AGN feedback in a disk galaxy using MACER II: predictions of X-ray surface brightness profiles and comparison with eROSITA observations

Abstract

Recently, we have performed a systematic study of AGN feedback in a disk galaxy within the MACER framework. Various model predictions, including the AGN duty cycle, the correlation between black hole accretion rates and star formation rates, and the (cold) gas fraction, have been compared with observations and will be presented in a series of papers. As the second paper in this series, without adjusting any model parameters, we directly use the simulation data introduced in Paper I to compute the predicted X-ray surface brightness profile and compare it with eROSITA observations of circumgalactic medium (CGM) emission around galaxies, which provide important constraints on AGN feedback models. For this comparison, we adopt two stacked eROSITA radial profiles of X-ray surface brightness: (1) distant galaxies with log(M*/M_sun) = 10.5-11.0 at z ~ 0.02-0.10 from Y. Zhang et al. (2024), and (2) nearby L* galaxies within 50 Mpc from L. He and Z. Li (2026). We find that the average simulated profile over time is in good agreement with the stacked measurements of Y. Zhang et al. (2024) over a broad radial range (out to ~100 kpc). Our model predictions also match the results of L. He and Z. Li (2026) at projected radii from ~20 kpc to 120 kpc. While our simulations, which predict only thermal emission, are consistent with these recent X-ray observations, the limitations in our current model mean that this agreement does not preclude a potential contribution from non-thermal emission, for example, from an extended halo of cosmic rays.