# Resolved galaxy scaling relations in the EAGLE simulation: star formation, metallicity and stellar mass on kpc scales

## TL;DR

This study uses the EAGLE simulation to analyze spatially resolved galaxy scaling relations, revealing their evolution over cosmic time and the impact of feedback processes on metallicity and star formation distributions.

## Contribution

It provides the first detailed comparison of spatially resolved star formation and metallicity relations in EAGLE with observations, highlighting their evolution and underlying physical mechanisms.

## Key findings

- EAGLE reproduces the slope of the local rSFMS with a small offset.
- The shape of the rMZR evolves from convex at z=2 to concave at z=0.1.
- Gas metallicity relations are non-local and evolve significantly over time.

## Abstract

We explore scaling relations between the physical properties of spatially resolved regions within the galaxies that emerge in the Evolution and Assembly of GaLaxies and their Environments (EAGLE) hydrodynamical, cosmological simulations. Using 1 kpc-scale spaxels, we compute the relationships between the star formation rate and stellar mass surface densities, i.e. the spatially resolved star-forming main sequence (rSFMS), and between the gas metallicity and the stellar mass surface density, i.e. the spatially resolved mass-metallicity relation (rMZR). We compare to observed relations derived from integral field unit surveys and imaging of galaxies. EAGLE reproduces the slope of the local ($z\approx0.1$) rSFMS well, but with a $\approx-0.15$ dex offset, close to that found for the galaxy-integrated relation. The shape of the rMZR agrees reasonably well with observations, replicating the characteristic turnover at high surface density, which we show is due to AGN feedback. The residuals of the rSFMS and rMZR are negatively (positively) correlated at low (high) surface density. The rSFMS becomes shallower as the simulation evolves from $z=2$ to 0.1, a manifestation of inside-out galaxy formation. The shape of the rMZR also exhibits dramatic evolution, from a convex profile at $z=2$ to the observed concave profile at $z=0.1$, such that the gas in regions of high stellar density is more enriched at higher redshift. The redshift independence of the relationship between the galaxy-wide gas fraction and metallicity in EAGLE galaxies is not preserved on 1 kpc scales, implying that chemical evolution is non-local due to the transport of gas and metals within galaxies.