Unveiling the trends between dust attenuation and galaxy properties at z ∼ 2−12 with the James Webb Space Telescope

¹ Faculty of Mathematics and Physics, University of Ljubljana, Jadranska ulica 19, SI-1000 Ljubljana, Slovenia
² Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
³ Dipartimento di Fisica “Enrico Fermi”, Universitá di Pisa, Largo Bruno Pontecorvo 3, Pisa I-56127, Italy
⁴ Department of Physics and Astronomy, University of California Davis, 1 Shields Avenue, Davis, CA 95616, USA
⁵ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone 00078, Italy
⁶ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA

^⋆ Corresponding author: vladan.markov@fmf.uni-lj.si

Received: 16 April 2025
Accepted: 5 August 2025

Abstract

Context. A large variety of dust attenuation and/or extinction curves has been observed in high-redshift galaxies. Some studies investigated their correlations with fundamental galaxy properties, which yielded mixed results. These variations are likely driven by underlying factors such as the intrinsic dust properties, the total dust content, and the spatial distribution of dust relative to stars.

Aims. We investigate the correlations between the shape of dust attenuation curves, defined by the UV-optical slope (S) and the UV bump parameter (B), and fundamental galaxy properties. Our goal is to identify the key physical mechanisms that shape the dust attenuation curves through cosmic time in the broader context of galaxy formation and evolution.

Methods. We extended the analysis of 173 dusty high-redshift (z ∼ 2 − 11.5) galaxies, whose dust attenuation curves were inferred by fitting James Webb Space Telescope (JWST) data with a modified version of the spectral energy distribution (SED) fitting code BAGPIPES. We investigate the trends between the dust attenuation parameters and different galaxy properties as inferred from the SED fitting: V-band attenuation (A_V), star formation rate (SFR), stellar mass (M_*), specific SFR (sSFR = SFR/M_∗), mass-weighted stellar age (⟨a⟩_*^m), ionization parameter (log U), and metallicity (Z). For a subset of sources, we additionally explored the trends with oxygen abundance (12 + log(O/H)), which we derived using the direct T_e-based method.

Results. We report moderate correlations between S and A_V, and B and A_V. Galaxies characterized by lower (higher) A_V exhibit steeper (flatter) slopes and stronger (weaker) UV bumps. These results agree with radiative transfer (RT) predictions that account for the total dust content and the relative spatial distribution of dust with respect to stars. Additionally, we find that S flattens with decreasing ⟨a⟩_*^m and increasing sSFR. These two trends can be explained if the strong radiation fields associated with young stars (low ⟨a⟩_*^m) and/or bursty galaxies (high sSFR) preferentially destroy small dust grains, which would shift the size distribution toward larger grains. Finally, the positive correlation between B and 12 + log(O/H) that emerged from our analysis might be driven by variations in the intrinsic dust properties with the gas metallicity.

Conclusions. The shape of the dust attenuation curves primarily correlates with four key galaxy properties: (1) With the redshift, which traces variations in the intrinsic and/or reprocessed dust properties, (2) with A_V, which reflects RT effects, (3) with the mass-weighted stellar age or sSFR, which might be driven by the radiation field strength, and (4) with the oxygen abundance, which might be linked to intrinsic dust properties. The overlap between some of these mechanisms makes it difficult to isolate their contributions, however. Further progress requires a combination of observations of a larger galaxy sample, point-like sources, spatially resolved galaxy studies, and theoretical models incorporating dust evolution in cosmological simulations.