Uncertainties in Galactic Chemical Evolution Models

TL;DR

This study quantifies uncertainties in galactic chemical evolution predictions caused by input parameters, using a Monte Carlo approach to analyze the impact on element abundances across different metallicities.

Contribution

It introduces a probabilistic framework to assess how input parameter uncertainties affect chemical evolution model predictions for the Milky Way.

Findings

Uncertainties vary with metallicity and element.

IMF slope and SNe Ia number are primary uncertainty sources.

Predicted element abundances have 68% and 95% confidence intervals.

Abstract

We use a simple one-zone galactic chemical evolution model to quantify the uncertainties generated by the input parameters in numerical predictions, for a galaxy with properties similar to those of the Milky Way. We compiled several studies from the literature to gather the current constraints for our simulations regarding the typical value and uncertainty of seven basic parameters, which are: the lower and upper mass limits of the stellar initial mass function (IMF), the slope of the high-mass end of the stellar IMF, the slope of the delay-time distribution function of Type Ia supernovae (SNe Ia), the number of SNeIa per Msun formed, the total stellar mass formed, and the final mass of gas. We derived a probability distribution function to express the range of likely values for every parameter, which were then included in a Monte Carlo code to run several hundred simulations with randomly selected input parameters. This approach enables us to analyze the predicted chemical evolution of 16 elements in a statistical way by identifying the most probable solutions along with their 68% and 95% confidence levels. Our results show that the overall uncertainties are shaped by several input parameters that individually contribute at different metallicities, and thus at different galactic ages. The level of uncertainty then depends on the metallicity and is different from one element to another. Among the seven input parameters considered in this work, the slope of the IMF and the number of SNe Ia are currently the two main sources of uncertainty.