There is more to outshining: 2D dust effects on stellar mass estimates at 3łeq z<9 with JWST in the JADES field

Year: 2026

Type: article

Abstract: Dust attenuation modifies the observed spectral energy distribution (SED), leading to biases in the physical parameters inferred from integrated SED fitting linked to degeneracies (e.g., between dust content and age). As spatially resolved SED modeling becomes feasible for large high-redshift samples, it is increasingly important to assess how dust attenuation affects resolved mass estimates. We evaluate the impact of dust attenuation on stellar mass estimates derived from integrating spatially resolved SED fitting results. We performed spatially resolved and integrated SED fitting on a sample of 3,408 galaxies at 3 łeq z < 9 from the Great Observatories Origins Deep Survey (GOODS) South Field, combining deep NIRCam from the JWST Advanced Deep Extragalactic Survey (JADES) and HST/ACS imaging from GOODS and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). We compared the galaxy-integrated properties derived from fitting the summed SED with those obtained from spatially resolved SED modeling. Using a two-component dust attenuation model with a variable slope, we investigated how the dust attenuation slope, A_V, and stellar population properties contribute to discrepancies in the resulting stellar mass estimates. We find that the resolved stellar masses are systematically higher than integrated ones, with a median offset of Deltałog _⋆ = +0.235 ± 0.003 dex (standard error of the median). The offset strongly depends on mass: $+0.35$ dex at łog _⋆/ _⊙ < 8, $+0.23$ dex at intermediate masses, and $+0.02$ dex at łog _⋆/ _⊙ > 10. Within our common SED-fitting framework, outshining by young stellar populations therefore affects low-mass galaxies most, where integrated fitting underestimates the mass by a factor of ∼2. Resolved fits recover higher attenuations (Δ A_V = +0.14 mag) and grayer ISM attenuation curves (Δδ_ M M M M M ISM = +0.15), from a preferential sampling of compact star-forming regions, while the ISM fraction of the attenuation, μ, is consistent between the two approaches. Integrated fits underestimate mass-weighted ages by ∼25% at z < 5 and ∼30% at z ≳ 5. Per galaxy, the mass offset correlates most strongly with the attenuation-slope difference (r = 0.76), then with the attenuation (r = 0.59) and age (r = 0.40) differences, pointing to age-dependent outshining and spatially varying dust geometry as the drivers. Systematic offsets are important for large samples, while individual galaxy mass estimates generally agree within the uncertainties.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202659082

Authors: M. Hamed, P. G. Pérez-González, M. Annunziatella, L. Colina, K. Małek, I. Shivaei, M. Perna, A.J. Bunker, S. Arribas, J. Álvarez-Márquez, C.N.A. Willmer, H. Übler, R. Bhatawdekar, J. Chevallard, E. Curtis-Lake, Z. Ji, P. Rinaldi, C.C. Williams

Language: English

Topic: Galaxies: Formation, Evolution, Phenomena

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,865

Funders: National Science Foundation, National Aeronautics and Space Administration, University of Arizona, Space Telescope Science Institute, European Commission, Ministerio de Ciencia e Innovación, Science and Technology Facilities Council, Agencia Estatal de Investigación

OpenAlex ID: W7223299245