This talk explores the distribution of neutral hydrogen (HI) and metals within galaxies / circumgalactic (CGM) / intergalactic media (IGM) using the CROCODILE cosmological hydrodynamic simulations performed by GADGET3/4-Osaka code, and insights from the AGORA code comparison project. Our simulations incorporate supernova (SN) and active galactic nucleus (AGN) feedback models to examine how these processes shape chemical enrichment and the distribution of baryons around galaxies. AGN feedback transports metals to intermediate scales, while SN feedback is the dominant driver on smaller scales, significantly influencing the structure of the CGM/IGM. In addition to feedback effects, we leverage variety of astrophysical models implemented in CROCODILE to study the HI distribution and metal enrichment in relation to the Lyman-alpha (Lyα) forest and large-scale IGM tomography. These approaches enable us to map the distribution of HI absorption features, providing a window into the IGM distribution. We highlight some results on the IGM tomography and bias relations in Lya forest distribution. This study connects simulations of galaxy evolution with observational strategies, including Lyα tomography, to deepen our understanding of the CGM and IGM in the early universe. The results offer valuable insights for future observational surveys (e.g. Subaru PFS) and aid in refining theoretical models of galaxy formation and the distribution of baryons on cosmological scales.

cf. CROCODILE website: https://sites.google.com/view/crocodilesimulation/home?authuser=0