Investigating the Circumgalactic Medium Using Simulations and Quasar Spectra

The circumgalactic medium (CGM) acts as a crucial interface between galaxies and the intergalactic medium, influencing galaxy evolution through gas accretion and feedback processes. In this study, we employ the Illustris-TNG and Sherwood cosmological simulations to perform a detailed analysis of the CGM surrounding galaxies across various masses and redshifts. By extracting lines of sight through the simulated CGM, we generate synthetic Lyman-alpha absorption spectra and compare these with observations from quasar sightlines. This comparison provides a direct observational test of the simulated gas distributions, ionization states, and kinematics.

Our analysis focuses on key physical properties of the CGM, including temperature, density, and metallicity, as well as the influence of stellar wind and AGN feedback on the physical properties of the gas. By juxtaposing the simulated spectra with real quasar absorption data, we aim to assess the agreement between simulations and observations, offering new insights into the mechanisms shaping the CGM. This work underscores the challenges in modeling the CGM and highlights areas where current simulations excel or fall short, helping to guide future developments in both simulations and observational techniques.