# Detailed dust modelling in the L-Galaxies semi-analytic model of galaxy formation

## TL;DR

This paper integrates a comprehensive dust evolution model into the L-Galaxies galaxy formation simulation, capturing dust sources, growth, and destruction processes across cosmic time, and compares results with observations.

## Contribution

It introduces a detailed dust model with separate grain growth in molecular clouds and a fit for the dust-to-metal ratio, improving predictions of dust evolution in galaxies.

## Key findings

- Dust production shifts from supernovae at high redshift to grain growth at lower redshift.
- The model reproduces observed relations between metallicity, dust-to-metal, and dust-to-gas ratios.
- Matches observed stellar mass–dust mass relation and dust mass function up to redshift 4.

## Abstract

We implement a detailed dust model into the L-Galaxies semi-analytical model which includes: injection of dust by type II and type Ia supernovae (SNe) and AGB stars; grain growth in molecular clouds; and destruction due to supernova-induced shocks, star formation, and reheating. Our grain growth model follows the dust content in molecular clouds and the inter-cloud medium separately, and allows growth only on pre-existing dust grains. At early times, this can make a significant difference to the dust growth rate. Above $z\sim8$, type II SNe are the primary source of dust, whereas below $z\sim8$, grain growth in molecular clouds dominates, with the total dust content being dominated by the latter below $z\sim6$. However, the detailed history of galaxy formation is important for determining the dust content of any individual galaxy. We introduce a fit to the dust-to-metal (DTM) ratio as a function of metallicity and age, which can be used to deduce the DTM ratio of galaxies at any redshift. At $z\lesssim3$, we find a fairly flat mean relation between metallicity and the DTM, and a positive correlation between metallicity and the dust-to-gas (DTG) ratio, in good agreement with the shape and normalisation of the observed relations. We also match the normalisation of the observed stellar mass -- dust mass relation over the redshift range of $0-4$, and to the dust mass function at $z=0$. Our results are important in interpreting observations on the dust content of galaxies across cosmic time, particularly so at high redshift.