Galaxy evolution in the cosmic web: the relative impact of nodes and filaments in the EAGLE simulation

TL;DR

This study uses the EAGLE simulation to analyze how the cosmic web's nodes and filaments influence galaxy evolution, revealing scale-dependent environmental effects on galaxy color and distribution.

Contribution

It introduces a novel analysis of the relative impacts of nodes and filaments on galaxies using an information-theoretic approach within the EAGLE simulation.

Findings

Red galaxies are near filament cores and nodes.

Characteristic transition scales are ~2.5 Mpc for nodes and ~0.75 Mpc for filaments.

Environmental influence on galaxy color is mass-dependent.

Abstract

Galaxies evolve within the intricate geometry of the cosmic web, yet the distinct roles of its primary components - nodes and filaments remain incompletely understood. Using the EAGLE cosmological hydrodynamical simulation, we investigate how distances to filament spines and cluster-scale nodes jointly and independently influence galaxy evolution. Galaxies are classified into red, green, and blue populations through a fully data-driven entropic thresholding technique, and the nodes and filaments are identified using DisPerSE. We find that red galaxies preferentially reside near filament cores and nodes, whereas blue galaxies dominate the outskirts. This spatial segregation reveals two characteristic transition scales: a node-related crossover at $\sim 2.5~\mathrm{Mpc}$ and a filament-related crossover at $\sim 0.75~\mathrm{Mpc}$. To further quantify environmental influence, we adopt an information-theoretic approach and measure the normalised mutual information between dominant mass component and galaxy colour across the $d_{\mathrm{f}}$-$d_{\mathrm{n}}$ plane. The mass-colour coupling increases with distance from nodes at fixed filament proximity, indicating a weakening of this relation in cluster-scale environments and a stronger coupling within filamentary regions. This behaviour is strongly mass dependent, with low-mass galaxies exhibiting a more pronounced environmental modulation than high-mass systems. These results support a scale-dependent view of galaxy evolution across the cosmic web, highlighting the distinct and complementary influence of nodes and filaments.