The impact of turbulent mixing on the galactic r-process enrichment by binary neutron star mergers

TL;DR

This study models how turbulent mixing affects the distribution of r-process elements from binary neutron star mergers in the galaxy, showing that these mergers can explain observed stellar abundances and their scatter.

Contribution

It introduces a semi-analytic galactic evolution model incorporating turbulent mixing to explain r-process enrichment from BNS mergers, aligning with observed stellar data.

Findings

BNS mergers can account for observed r-process abundance scatter in Milky Way stars.

Turbulent mixing disperses elements gradually, matching observed abundance patterns.

Binary neutron star mergers could be the main source of r-process elements in the Galaxy.

Abstract

We study the enrichment of the interstellar medium with rapid neutron capture (r-process) elements produced in binary neutron star (BNS) mergers. We use a semi-analytic model to describe galactic evolution, with merger rates and time delay distributions of BNS mergers consistent with the latest population synthesis models. In order to study the dispersion of the relative abundances of r-process elements and iron, we applied a turbulent mixing scheme, where the freshly synthesized elements are gradually dispersed in the interstellar medium. We show that within our model the abundances observed in Milky-Way stars, in particular the scatter at low metallicities, can be entirely explained by BNS mergers. Our results suggest that binary neutron star mergers could be the dominant source of r-process elements in the Galaxy.