SPH simulations of the chemical evolution of bulges

TL;DR

This paper presents high-resolution SPH simulations of spiral galaxy formation incorporating detailed chemical evolution, feedback mechanisms, and metal diffusion to study bulge stellar populations and their formation history.

Contribution

It introduces a chemical evolution model integrated into the DEVA code, including feedback and diffusion, to simulate bulge formation and analyze stellar populations.

Findings

Bulges may consist of two stellar populations: old, metal-poor, alpha-enriched and younger, accreted.

Simulation results support a multiclump early formation scenario for bulges.

Metal diffusion influences the chemical composition of the resulting stellar populations.

Abstract

We have implemented a chemical evolution model on the parallel AP3M+SPH DEVA code which we use to perform high resolution simulations of spiral galaxy formation. It includes feedback by SNII and SNIa using the Qij matrix formalism. We also include a diffusion mechanism that spreads newly introduced metals. The gas cooling rate depends on its specific composition. We study the stellar populations of the resulting bulges finding a potential scenario where they seem to be composed of two populations: an old, metal poor, $\alpha$-enriched population, formed in a multiclump scenario at the beginning of the simulation and a younger one, formed by slow accretion of satellites or gas, possibly from the disk due to instabilities.