# The inflow and outflow rate evolution of local Milky Way-mass star-forming galaxies since z=1.3

## TL;DR

This study investigates the evolution of gas inflow and outflow rates in Milky Way-mass star-forming galaxies since redshift 1.3, revealing a significant decline in inflow rates over cosmic time and constraining outflow rates through metallicity modeling.

## Contribution

It provides the first detailed quantification of inflow and outflow rate evolution in Milky Way-mass galaxies since z=1.3 using gas scaling relations and metallicity modeling.

## Key findings

- Inflow rate decreases by ~80% from z=1.3 to z=0.5.
- Outflow rate is approximately 0.5-0.8 times the SFR.
- Net inflow rate is comparable to SFR at z~1.3 and drops significantly by z=0.

## Abstract

We study the gas inflow rate ($\zeta_{\rm inflow}$) and outflow rate ($\zeta_{\rm outflow}$) evolution of local Milky Way-mass star-forming galaxies (SFGs) since $z=1.3$. The stellar mass growth history of Milky Way-mass progenitor SFGs is inferred from the evolution of the star formation rate (SFR)$-$stellar mass ($M_{\ast}$) relation, and the gas mass ($M_{\rm gas}$) is derived using the recently established gas scaling relations. With the $M_{\ast}+M_{\rm gas}$ growth curve, the net inflow rate $\kappa$ is quantified at each cosmic epoch. At $z\sim 1.3$, $\kappa$ is comparable with the SFR, whereas it rapidly decreases to $\sim 0.15\times$SFR at $z=0$. We then constrain the average outflow rate $\zeta_{\rm outflow}$ of progenitor galaxies by modeling the evolution of their gas-phase metallicity. The best-fit $\zeta_{\rm outflow}$ is found to be $(0.5-0.8)\times$SFR. Combining $\kappa$ and $\zeta_{\rm outflow}$, we finally investigate the evolution of $\zeta_{\rm inflow}$ since $z=1.3$. We find that $\zeta_{\rm inflow}$ rapidly decreases by $\sim$80\% from $z=1.3$ to $z=0.5$. At $z<0.5$, $\zeta_{\rm inflow}$ continuously decreases but with a much lower decreasing rate. Implications of these findings on galaxy evolution are discussed.