Metal-loaded outflows in sub-Milky Way galaxies in the CIELO simulations

TL;DR

This study uses high-resolution simulations to analyze how supernova-driven outflows in sub-Milky Way galaxies influence metal distribution, star formation regulation, and galaxy evolution from redshift 0 to 7.

Contribution

It provides new insights into the chemical evolution and outflow properties of sub-Milky Way galaxies, highlighting the role of supernova feedback in metal enrichment and gas dynamics.

Findings

Sub-MW galaxies retain more oxygen in gas phase but expel significant amounts beyond virial radius.

Low-mass galaxies have 10-40% of oxygen in CGM and 10-60% in IGM, unlike more massive galaxies.

Outflows in sub-MW galaxies are more oxygen-rich (Zout/ZISM ~ 1.5) than in higher-mass galaxies.

Abstract

Supernova (SN) feedback-driven galactic outflows are a key physical process that contributes to the baryon cycle by regulating the star formation activity, reducing the amount of metals in low-mass galaxies and enriching the circumgalactic (CGM) and intergalactic media (IGM). We aim to understand the chemical loop of sub-Milky Way (MW) galaxies and their nearby regions. We studied 15 simulated central sub-MW galaxies (M* <= 10^10 Msun) and intermediate-mass galaxies (M* \sim 10^10 Msun) from the CIELO-P7 high-resolution simulations. We followed the evolution of the progenitor galaxies, their properties and the characteristics of the outflows within the redshift range z = [0, 7]. We used two dynamically-motivated outflow definitions, unbound outflows and expelled mass rates, to quantify the impact of SN feedback. At z \sim 0, sub-MW galaxies have a larger fraction of their current oxygen mass in the gas phase but have expelled a greater portion beyond the virial radius, compared to their higher-mass counterparts. Galaxies with M* <\sim 10^9 Msun have 10-40 per cent of their total oxygen mass within R200 in the CGM, and an equivalent to 10-60 per cent expelled into the IGM. In contrast, more massive galaxies have most of the oxygen mass locked by the stellar populations. The CGM of low-mass galaxies predominantly contains oxygen low-temperature gas, acting as a metal reservoir. We find that the outflows are more oxygen-rich for sub-MW galaxies, Zout/ZISM \sim 1.5, than for higher-mass galaxies, Zout/ZISM <= 0.5, particularly for z < 2. Mass-loading factors of eta_out \sim 0 - 6 are detected in agreement with observations (abridged).