A Computational Analysis of Galactic Metallicity Evolution Utilizing IllustrisTNG 59 views

The chemical enrichment of galaxies serves as a record of their star formation histories and the baryon cycle. Tracking the distribution of heavy elements provides constraints on the efficiency of galactic feedback mechanisms and cosmological gas accretion. In this study, we utilize the IllustrisTNG hydrodynamical simulation (specifically the high-resolution TNG50) to investigate the thermodynamic phase-space and morphological evolution of gas-phase metallicity from the early universe (z=6) to the present day (z=0). We partition the galactic gas into the interstellar medium (ISM), the hot circumgalactic medium (hot CGM), and the diffuse, cool halo to quantify the mass-dependent migration of heavy elements across cosmic time. Our analysis shows that the global normalization of the mass-metallicity relation (MZR) steadily decreases towards higher redshifts, mainly driven by continuous dilution from massive inflows of pristine gas rather than intrinsic retention failures. Coupled with a depletion of the diffuse, cool gas phase at early cosmic times, these breaks demonstrate the absence of a deep, stabilizing gravitational potential well and are demonstrated by morphological projections. We conclude that the early universe is dominated by intense feedback that ejects nucleosynthetic yields from weak, shallow potential wells before a stable gradient can form. In contrast, the local universe exhibits a strongly mass-dependent baryon cycle, where intermediate systems stabilize and retain their metals within the star-forming disk, while high-mass subhalos experience gas clearing driven by AGN feedback. These findings provide quantitative benchmarks for understanding the interaction between gravitational assembly, cosmological accretion, and multi-phase galactic outflows.

BS (Bachelor of Science)

galactic gas; heavy elements; yields

English

2026-05-06