Large Ly α opacity fluctuations and low CMB τ in models of late reionization with large islands of neutral hydrogen extending to <i>z</i> &lt; 5.5
Why this work is in the frame
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Bibliographic record
Abstract
Abstract High-redshift quasi-stellar object (QSO) spectra show large spatial fluctuations in the Ly α opacity of the intergalactic medium on surprisingly large scales at $z$ ≳ 5.5. We present a radiative transfer simulation of cosmic reionization driven by galaxies that reproduces this large scatter and the rapid evolution of the Ly α opacity distribution at 5 &lt; $z$ &lt; 6. The simulation also reproduces the low Thomson scattering optical depth reported by the latest cosmic microwave background (CMB) measurement and is consistent with the observed short near-zones and strong red damping wings in the highest redshift QSOs. It also matches the rapid disappearance of observed Ly α emission by galaxies at $z$ ≳ 6. Reionization is complete at $z$ = 5.3 in our model, and 50 per cent of the volume of the Universe is ionized at $z$ = 7. Agreement with the Ly α forest data in such a late reionization model requires a rapid evolution of the ionizing emissivity of galaxies that peaks at $z$ ∼ 6.8. The late end of reionization results in a large scatter in the photoionization rate and the neutral hydrogen fraction at redshifts as low as $z$ ≲ 5.5 with large residual neutral ‘islands’ that can produce very long Gunn–Peterson troughs resembling those seen in the data.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it