Effects of dust sources on dust attenuation properties in IllustrisTNG galaxies at $z\sim 7$

TL;DR

This study uses radiative transfer simulations based on IllustrisTNG to explore how different dust sources affect attenuation and emission properties of high-redshift galaxies, revealing complex dependencies that challenge simple source identification.

Contribution

It introduces a realistic geometric approach to modeling dust attenuation in $z\, extasciitilde 7$ galaxies, highlighting the impact of dust sources on observable properties.

Findings

Attenuation curves differ significantly from original extinction curves.

Different dust sources produce distinct IRX-$eta$ relations.

Dust growth influences the IRX-$eta$ sequence with smaller IRX values.

Abstract

Dust emission from high-redshift galaxies gives us a clue to the origin and evolution of dust in the early Universe. Previous studies have shown that different sources of dust (stellar dust production and dust growth in dense clouds) predict different ultraviolet (UV) extinction curves for galaxies at $z\sim 7$ but that the observed attenuation curves depend strongly on the geometry of dust and star distributions. Thus, we perform radiative transfer calculations under the dust-stars geometries computed by a cosmological hydrodynamic simulation (IllustrisTNG). This serves to investigate the dust attenuation curves predicted from `realistic' geometries. We choose objects with stellar mass and star formation rate appropriate for Lyman break galaxies at $z\sim 7$. We find that the attenuation curves are very different from the original extinction curves in most of the galaxies. This makes it difficult to constrain the dominant dust sources from the observed attenuation curves. We further include infrared dust emission in the analysis and plot the infrared excess (IRX)-UV spectral slope ($\beta$) diagram. We find that different sources of dust cause different IRX-$\beta$ relations for the simulated galaxies. In particular, if dust growth is the main source of dust, a variation of dust-to-metal ratio causes a more extended sequence with smaller IRX in the IRX-$\beta$ diagram. Thus, the comprehensive analysis of the abundances of dust and metals, the UV slope, and the dust emission could provide a clue to the dominant dust sources in the Universe.