A Monte Carlo based simulation of the galactic chemical evolution of the Milky Way galaxy

TL;DR

This paper develops a Monte Carlo simulation to model the Milky Way's chemical evolution, analyzing how different accretion scenarios, star formation efficiency, and gas flows influence elemental abundance gradients and galactic structure.

Contribution

It introduces a novel Monte Carlo approach incorporating multiple accretion scenarios and SN Ia delay time distributions to better predict galactic chemical evolution.

Findings

Steep inner and shallow outer abundance gradients match observations.

Radial gas inflows explain the inversion of abundance gradients around 2 Gyr.

Three-infall model outperforms two-infall in explaining halo and disc compositions.

Abstract

The formation and chemical evolution of the Milky Way Galaxy is numerically simulated by developing a Monte Carlo approach to predict the elemental abundance gradients and other galactic features using the revised solar abundance. The galaxy is accreted gradually by using either a two-infall or a three-infall accretion scenario. The galaxy is chemically enriched by the nucleosynthetic contributions from an evolving ensemble of generations of stars. We analyse the role of star formation efficiency. The influence of the radial gas inflow as well as radial gas mixing on the evolution of galaxy is also studied. The SN Ia delay time distribution (DTD) is incorporated by synthesizing SN Ia populations using random numbers based on a distribution function. The elemental abundance evolutionary trends corroborate fractional contributions of ~0.1 from prompt ( < 100 Myr) SN Ia population. The models predict steep gradients in the inner regions and less steep gradients in the outer regions which agrees with the observations. The gradients indicate an average radial gas mixing velocity of < 1 km/s. The models with radial gas inflows reproduce the observed inversion in the elemental abundance gradients around 2 billion years. The three-infall accretion scenario performs better than the two-infall accretion model in terms of explaining the elemental abundance distributions of the galactic halo, thick and thin discs. The accuracy of all the models has been monitored as a cumulative error of < 0.15 M in the mass balance calculations during the entire evolution of the galaxy.