Dust emission from the bulk of galaxies in the Epoch of Reionisation
Bibliographic record
Abstract
The excess of UV-bright galaxies observed at z > 10 has been one of the major surprises of the early JWST observations. Several explanations have been proposed to understand the mild change in space density of the UV-bright galaxies at these high redshifts, among them an evolution of dust attenuation properties in galaxies. However, our view of dust in primordial galaxies is limited towards a few tens of z ∼ 7 galaxies, pre-selected from UV-optical observations, and are thus not necessarily representative of the bulk of the sources at these redshifts. In this work, we aim to constrain the dust properties of galaxies at 6 < z < 12 by making the most of the A 3 COSMOS database in the JADES/GOODS-South field. We stacked ALMA band 6 and 7 observations of 4464 JADES galaxies covered by the A 3 COSMOS database and used the measurements as constraints to perform UV-to-FIR SED modelling. We obtained tentative signals for the brightest UV galaxies ( M UV < −19 mag) as well as for the most massive ones (log M ⋆ / M ⊙ > 9) at 6 < z < 7, and upper limits for fainter ( M UV > −19 mag), lower-mass sources (log M ⋆ / M ⊙ < 9), or ones at higher redshift ( z > 7). Fitting these 6 < z < 7 galaxies with ALMA constraints results in lower star formation rates (−0.4 dex) and FUV attenuation (−0.5 mag) for galaxies with log M ⋆ / M ⊙ > 8, compared to the fit without FIR. We extend the L IR vs M UV relation down to M UV = −19 mag and show a tentative breakdown of the relation at fainter UV magnitudes. The positions of the JADES z ∼ 6.5 sample on the infrared excess (IRX) versus β and IRX versus M ⋆ diagrams are consistent with the ones of the ALPINE ( z ∼ 5.5) and REBELS ( z ∼ 6.5) samples, suggesting that the dust composition and content of our mass-selected sample are similar to the ones of these UV-selected galaxies. Extending our analysis of the infrared properties to z > 7 galaxies, we find a non-evolution of β in the M UV range probed by our sample (–17.24 −0.62 +0.54 ), and highlight the fact that samples from the literature are not representative of the bulk of galaxy populations at z > 6. We confirm a linear relation between A V and sSFR −1 with a flatter slope than previously reported due to the use of ALMA constraints. Our results suggest that rapid and significant dust production has already happened by z ∼ 7.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".