Cosmological hydrodynamical simulations with calibrated non-universal initial mass functions

点击翻译按钮获取中文摘要

This project aims to analyse how implementing a calibrated variable stellar initial mass function (IMF) into a modern large-scale hydrodynamical simulation affects wider galactic properties. A universal IMF fixes the distribution of mass within a stellar population independent of the conditions under which the stars formed. This is a widely accepted approximation in galaxy formation models, but recent observations of high-mass early-type galaxies (ETGs) indicate excesses in their mass-to-light ratios in comparison to the Milky Way. The mass-to-light excess (MLE) can be corrected by adapting the IMF to allow an overabundance of low-mass dwarf stars (making the IMF bottom-heavy in mass) and/ or stellar remnants (making the IMF top-heavy) such that the mass in stars in ETGs is increased without altering the luminosity of the stars. Implementing a variable IMF that explains the observed MLE into a galaxy formation model will subsequently affect stellar feedback and stellar formation rates among other galactic processes, meaning that simulations must be altered and run self-consistently in order to accurately analyse how a variable IMF may affect the evolution of galaxies. To this end, this project will calibrate a variable IMF based on observed MLE relations and analyse how incorporating this IMF into a state-of-the-art hydrodynamical simulation affects galaxy properties.