Three intervening galaxy absorbers towards GRB 060418: faint and dusty?
Bibliographic record
Abstract
Abstract We present an analysis of three strong, intervening Mg II absorption systems (zabs = 0.603, 0.656, 1.107) towards the optical afterglow of gamma-ray burst (GRB) 060418. From high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) spectra we measure metal column densities and find that the highest redshift absorber exhibits a large amount of dust depletion compared with damped Lyman absorbers (DLAs) seen in quasi-stellar object (QSO) spectra. The intervening zabs = 1.107 absorber is also unusual in exhibiting a clear 2175-Å bump, the first time this feature has been definitively detected in a GRB spectrum. The GRB afterglow spectrum is best fitted with a two-component extinction curve: a Small Magellanic Cloud (SMC) extinction law at z = 1.49 (the redshift of the host) with E(B−V) = 0.07 ± 0.01 and a Galactic extinction curve at z∼ 1.1 with E(B−V) = 0.08 ± 0.01. We also present a moderately deep New Technology Telescope (NTT) R-band image of the GRB 060418 field and spectroscopy of four galaxies within 1 arcmin. None of these objects has a redshift that matches any of the intervening absorbers, and we conclude that the galaxies responsible for the two intervening Mg ii absorbers at z∼ 0.6 have luminosities .
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".