CANUCS: UV and ionizing properties of dwarf star-forming galaxies at <i>z</i> ~ 5–7
Bibliographic record
Abstract
ABSTRACT The epoch of reionization (EoR) progressed through the emission of ionizing photons from galaxies to their local intergalactic medium. In this work, we characterize the dwarf star-forming galaxies as candidates for the source of ionizing photons that drove EoR. We investigate the ionizing properties and star formation histories of star-forming dwarf galaxies at the last stages of EoR at $4.8\lt z \lt 7$ using observations from the CAnadian NIRISS Unbiased Cluster Survey (CANUCS). The magnification due to gravitational lensing allows us to probe large dynamic ranges in stellar mass ($2\times 10^{6}\le {M}_*/{\rm M}_\odot \le 5\times 10^{9}$) and ultraviolet (UV) magnitudes ($-22.68\le M_{\rm UV}\le =-15.95$). We find a median UV slope $\beta _{1500}\,$ of $-2. 56\pm 0.23$ and the production efficiency of ionizing photons $\log$$\xi _{\rm {ion}}\,$$=25.39\pm 0.6$ for the full sample ($4.8\lt z \lt 7$) with a median stellar mass of $6.3\pm 0.5\times 10^{7} \, {\rm M}_\odot$. We find both $\beta _{1500}\,$ and $\xi _{\rm {ion}}\,$ are marginally correlated with the stellar mass of the galaxy, indicating a possible greater contribution of dwarf galaxies to the reionization of the Universe. We find that on average, galaxies in our sample are experiencing a recent rise/burst of star formation which translates to a higher scatter in $\xi _{\rm {ion}}\,$ and a large scatter in H$\alpha$ equivalent widths (EWs). Finally, we investigate the trends of H$\alpha$ and [O iii] + H$\beta$ EWs with UV magnitude and find $M_{\rm UV}$ is correlated between H$\alpha$ but not with [O iii] + H$\beta$ EWs indicating low metallicities and recent burst in the UV faint galaxies.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".