The role of the cosmic web in the scatter of the galaxy stellar mass - gas metallicity relation

TL;DR

This study reveals that a galaxy's proximity to cosmic web nodes influences its gas-phase metallicity, with closer galaxies showing higher enrichment, supported by observational SDSS data and simulations from IllustrisTNG.

Contribution

It demonstrates a clear impact of cosmic web structures on galaxy metallicity, linking environment to galaxy evolution in a novel way.

Findings

Galaxies near nodes have higher metallicity than those farther away.

Proximity to filaments also affects metallicity but less strongly.

Simulation results support the observational findings and suggest mechanisms involving halo assembly bias and gas supply.

Abstract

Understanding the relationship between the cosmic web and the gas content of galaxies is a key step towards understanding galaxy evolution. However, the impact of the cosmic web on the growth of galaxies and dark matter halos is not yet properly understood. We report a detection of the effect of the cosmic web on the galaxy stellar mass - gas phase metallicity relation of low redshift star-forming galaxies, using SDSS data. The proximity of a galaxy to a node, independently of stellar mass and overdensity, influences its gas-phase metallicity, with galaxies closer to nodes displaying higher chemical enrichment than those further away. We find a similar but significantly weaker effect with respect to filaments. We supplement our observational analysis with a study of the cosmological hydrodynamical simulation IllustrisTNG (TNG300), finding qualitative agreement with our results. Using IllustrisTNG, our results can be explained by both halo assembly bias and gas supply combining in nodes in a way that significantly modulates the metallicity of the gas, contributing to the scatter of this fundamental relation in galaxy evolution.