The process of galaxy evolution over cosmic times is not yet fully understood since there is a debate on the impact of galaxy collisions on star formation and metallicity. The local environment of the galaxy mergers could also have a large impact on the evolution of the galaxies, but it has not yet been possible to examine it in detail. Modern simulations with a larger capacity, including the newest physical knowledge and new observations with JWST help us to answer these questions.
Using the IllustrisTNG cosmological simulation, we processed the catalogue data and the merger tree files of the TNG100-1 and the TNG300-1 simulations. We calculated the galaxies’ average star formation rate (SFR), metallicity, and mass at redshifts between 0 < z < 15. We investigated the environment of the galaxy mergers, with the focus on the local density and compared our findings with JWST results, which gives us the opportunity to improve simulation models.
From the galaxy mergers’ star formation history, we can conclude that due to the mergers, the average SFR of the galaxies is increasing. The SFR of the galaxies is highly increasing at a critical density, and the number of galaxies peaks at the star formation rate density (SFRD) maximum. The SFRD history in the IllustrisTNG simulation differs from JWST results.