The Growth of Dust in Galaxies in the First Billion Years with Applications to Blue Monsters
Year: 2026
Type: article
Abstract: A combination of JWST observations at z~12-14 and ALMA observations of extremely dust-rich systems at z~6 has demonstrated that dust grows extremely fast in the early Universe, with galaxies amassing up to 10^7 Msun of dust in just 500 Myr between z=12->6. In this paper we demonstrate, via a series of numerical experiments conducted in cosmological zoom-in simulations, that a likely pathway for this dust accumulation in the first formed galaxies is through production at early times via supernovae, followed by the rapid growth on ultrasmall dust grains. Our main results follow. The stellar production of dust dominates until z ~ 10-11 at which point galaxies transition to a growth-dominated regime. We employ a Shapley analysis to demonstrate that the local density is the dominant factor driving dust growth, followed by the grain size distribution. A rapid rise in the small-to-large grain ratio with decreasing redshift (owing to grain-grain shattering) drives growth through increased dust surface area per unit mass. Growth models are necessary to match the dust content of ALMA detected sources at z ~ 6. Finally, we demonstrate that ``blue monsters’’, massive, UV-bright galaxies at z > 10 with extremely blue continuum slopes likely have dust-to stellar mass ratios 10 -4-10 -3, but their top-heavy grain size distributions render them optically thin in the UV, providing a natural explanation for their observed properties without requiring exotic dust geometries.
Source: The Open Journal of Astrophysics
DOI: 10.33232/001c.159986
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4416257588