A Local Leaky-box Model for the Local Stellar Surface Density - Gas Surface Density - Gas Phase Metallicity Relation

TL;DR

This paper introduces a local leaky-box model that explains the tight relationship between stellar surface density, gas surface density, and metallicity in disk galaxies, supported by SDSS-IV/MaNGA data.

Contribution

It presents a new analytical leaky-box model for local galaxy evolution that matches observed relations and offers a pathway to improve galaxy formation simulations.

Findings

The model accurately reproduces the observed stellar-gas-metallicity relation.

The relation is independent of initial conditions and time.

The model can be integrated into semi-analytic galaxy formation frameworks.

Abstract

We revisit the relation between the stellar surface density, the gas surface density, and the gas-phase metallicity of typical disk galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g., by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disk galaxies, such as the size growth and the global stellar mass-gas metallicity relation.