Chemodynamics of a Simulated Disc Galaxy: Initial Mass Functions and SNIa Progenitors

TL;DR

This study uses cosmological simulations to explore how different initial mass functions and supernova progenitor assumptions affect the chemical evolution of a simulated galaxy, revealing sensitivities and degeneracies in these parameters.

Contribution

It introduces a detailed simulation framework that tests various IMFs and supernova parameters to understand their impact on galaxy chemical evolution.

Findings

SNII progenitors up to 100 Msun are needed for low metallicity oxygen.

Tardy SNIa are essential to reproduce the chemical evolution knee.

Chemical evolution depends on IMF shape and SNII mass range.

Abstract

We trace the formation and advection of several elements within a cosmological adaptive mesh refinement simulation of an L* galaxy. We use nine realisations of the same initial conditions with different stellar Initial Mass Functions (IMFs), mass limits for type-II and type-Ia supernovae (SNII, SNIa) and stellar lifetimes to constrain these sub-grid phenomena. Our code includes self-gravity, hydrodynamics, star formation, radiative cooling and feedback from multiple sources within a cosmological framework. Under our assumptions of nucleosynthesis we find that SNII with progenitor masses of up to 100 Msun are required to match low metallicity gas oxygen abundances. Tardy SNIa are necessary to reproduce the classical chemical evolution knee in [O/Fe]-[Fe/H]: more prompt SNIa delayed time distributions do not reproduce this feature. Within our framework of hydrodynamical mixing of metals and galaxy mergers we find that chemical evolution is sensitive to the shape of the IMF and that there exists a degeneracy with the mass range of SNII. We look at the abundance plane and present the properties of different regions of the plot, noting the distinct chemical properties of satellites and a series of nested discs that have greater velocity dispersions, are more alpha-rich and metal poor with age.