Thinking outside the halo: Tracing the large-scale distribution of diffuse cosmic metals with semi-analytic models

TL;DR

This study uses semi-analytic models to explore how supernova feedback influences the distribution of metals in the low-redshift intergalactic medium, aligning with recent observations and hydrodynamic simulations.

Contribution

It introduces a grid-based diffuse gas model coupled with SAGE to analyze supernova feedback effects on IGM metal pollution, considering various assumptions about gas reheating and ejection.

Findings

Most likely IGM metallicity is between -1.5 and -1.0 in log scale at z=0.

High-metallicity IGM regions are near galaxies with stellar mass ~10^{10.5}h^{-1}M_sun.

90% of IGM metals at z=0 are ejected by galaxies with stellar mass less than 10^{10.33}h^{-1}M_sun.

Abstract

With the installation of the Cosmic Origins Spectrograph on the Hubble Space Telescope, measurements of the metal content of the low redshift intergalactic medium (IGM) are now available. Using a new grid-based model for diffuse gas coupled to the SAGE semi-analytic model of galaxy formation, we examine the impact of supernova feedback on the pollution of the IGM. We consider different assumptions for the reheating and ejection of gas by supernovae and their dependence on galaxy circular velocity and gas surface density. Where metals are present, we find the most likely metallicity to be $-1.5 < $log$_{10}$(Z/Z$_{\odot}$)$< -1.0$ at $z = 0$, consistent with both observations and more sophisticated hydrodynamic simulations. Our model predicts that the regions of the IGM with the highest metallicities will be near galaxies with M$_{\star} \sim 10^{10.5}h^{-1}$M$_{\odot}$ and in environments of densities $\sim 10 \times$ the mean. We also find that 90% of IGM metals at $z = 0$ are ejected by galaxies with stellar masses less than $10^{10.33}h^{-1}$M$_{\odot}$.