How Dust Models Shape High-z Galaxy Morphology: Insights from the NewCluster Simulation

TL;DR

This study demonstrates that on-the-fly dust modeling in galaxy simulations significantly influences galaxy morphology, producing brighter centers and fewer late-type galaxies compared to fixed dust models, aligning better with JWST observations.

Contribution

It introduces a detailed on-the-fly dust model in cosmological simulations and compares its effects on galaxy morphology to traditional fixed dust models.

Findings

OTF dust models produce brighter galaxy centers and more prominent bulges.

Fixed DTM models underestimate central brightness and bulge prominence.

The DTM cavity phenomenon affects galaxy morphology at high redshift.

Abstract

Dust plays a pivotal role in shaping the observed morphology of galaxies. While traditional cosmological simulations often assume a fixed dust-to-gas (DTG) or dust-to-metal (DTM) mass ratio to model dust effects, recent advancements have enabled on-the-fly (OTF) dust modeling that captures the spatial and temporal evolution of dust. In this work, we investigate the impact of dust modeling on galaxy morphology using the NewCluster simulation, which implements a detailed OTF dust model. We generate mock images of NewCluster galaxies under both OTF and fixed DTM models using the radiative transfer code SKIRT, and compare their morphology to JWST observations. We measure morphology indices and use the $G-M_{20}$ test to classify galaxies. We find that the OTF galaxy models exhibit brighter centers and more pronounced bulges than those of the fixed DTM models, resulting in a lower late-type galaxy (LTG) fraction, particularly at high redshifts. This central brightening is linked to a phenomenon we refer to as the DTM cavity, a localized depression in the DTM ratio driven by intense bulge starbursts. Our results highlight the importance of modeling dust evolution in a physically motivated manner, as fixed DTM models fail to capture key morphological features.