Impact of radial migration on stellar and gas radial metallicity distribution

TL;DR

This study uses simulations to analyze how radial migration influences the distribution of metallicity in stars and gas within galactic discs, revealing that migration broadens stellar metallicity dispersion while maintaining a narrow gas metallicity distribution.

Contribution

It demonstrates the differential impact of radial migration on stellar and gas metallicity distributions in a Milky Way-sized galaxy simulation.

Findings

Stellar metallicity dispersion increases with migration, but the gradient remains stable.

Gas metallicity distribution stays narrow due to efficient mixing and enrichment.

The simulated metallicity distribution aligns with observed age-metallicity trends for young stars.

Abstract

Radial migration is defined as the change in guiding centre radius of stars and gas caused by gains or losses of angular momentum that result from gravitational interaction with non-axisymmetric structure. This has been shown to have significant impact on the metallicity distribution in galactic discs, and therefore affects the interpretation of Galactic archeology. We use a simulation of a Milky Way-sized galaxy to examine the effect of radial migration on the star and gas radial metallicity distribution. We find that both the star and gas component show significant radial migration. The stellar radial metallicity gradient remains almost unchanged but the radial metallicity distribution of the stars is broadened to produce a greater dispersion at all radii. However, the metallicity dispersion of the gas remains narrow. We find that the main drivers of the gas metallicity distribution evolution are metal enrichment and mixing: more efficient metal enrichment in the inner region maintains a negative slope in the radial metallicity distribution, and the metal mixing ensures the tight relationship of the gas metallicity with the radius. The metallicity distribution function reproduces the trend in the age-metallicity relation found from observations for stars younger than 1.0 Gyr in the Milky Way.