JADES: primaeval Lyman α emitting galaxies reveal early sites of reionization out to redshift <i>z</i> ~ 9
Bibliographic record
Abstract
ABSTRACT Given the sensitivity of the resonant Lyman $\alpha$ (Ly $\alpha $) transition to absorption by neutral hydrogen, observations of Ly $\alpha$ emitting galaxies (LAEs) have been widely used to probe the ionizing capabilities of reionization-era galaxies and their impact on the intergalactic medium (IGM). However, prior to JWST our understanding of the contribution of fainter sources and of ionized ‘bubbles’ at earlier stages of reionization remained uncertain. Here, we present the characterization of three exceptionally distant LAEs at $z \gt 8$, newly discovered by JWST/Near-Infrared Spectrograph in the JADES survey. These three similarly bright ($M_\text{UV} \approx -20 \, \mathrm{mag}$) LAEs exhibit small Ly $\alpha$ velocity offsets from the systemic redshift, $\Delta v_\rm{{Ly\alpha }} \lesssim 200 \, \mathrm{km \, s^{-1}}$, yet span a range of Ly $\alpha$ equivalent widths (15, 31, and $132 \, \mathring{\rm A}$). The former two show moderate Ly $\alpha$ escape fractions ($f_\rm{esc, {Ly\alpha }} \approx 10~{{\rm per\,cent}}$), whereas Ly $\alpha$ escapes remarkably efficiently from the third ($f_\rm{esc, {Ly\alpha }} \approx 72~{{\rm per\,cent}}$), which moreover is very compact (half-light radius of $90 \pm 10 \, \mathrm{pc}$). We find these LAEs are low-mass galaxies dominated by very recent, vigorous bursts of star formation accompanied by strong nebular emission from metal-poor gas. We infer the two LAEs with modest $f_\rm{esc, {Ly\alpha }}$, one of which reveals evidence for ionization by an active galactic nucleus, may have reasonably produced small ionized bubbles preventing complete IGM absorption of Ly $\alpha$. The third, however, requires a $\sim \!3 \, \text{physical Mpc}$ bubble, indicating faint galaxies have contributed significantly. The most distant LAEs thus continue to be powerful observational probes into the earlier stages of reionization.
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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 | 0.000 |
| 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".