A massive bubble of extremely metal-poor gas around a collapsing Lyα blob at z = 2.54
Bibliographic record
Abstract
Using long-slit optical spectroscopy obtained at the 10.4 m Gran Telescopio Canarias, we have examined the gaseous environment of the radio-loud quasar TXS 1436+157 (z = 2.54), previously known to be associated with a large Lyα nebula and a spatially extended Lyα-absorbing structure. From the Lyα nebula, we measure kinematic properties consistent with infall at a rate of ∼10–100 M⊙ yr−1 – more than sufficient to power a quasar at the top of the luminosity function. The absorbing structure lies outside of the Lyα nebula, at a radius of ≳ 40 kpc from the quasar. Against the bright unresolved continuum and line emission from the quasar, we detect in absorption the N v λλ1239, 1241, C iv λλ1548, 1551 and Si iv λλ1394, 1403 doublets, with no unambiguous detection of absorption lines from any low-ionization species of metal. The metal column densities, taken together with the H i column density measurement from the literature, indicate that the absorbing gas is predominantly ionized by the quasar, has a mass of hydrogen of ≳ 1.6 × 1011 M⊙, a gas density of ≤18 cm−3, a line-of-sight thickness of ≥18 pc and a covering factor approaching unity. While this absorbing structure is clearly not composed of pristine gas, it has an extremely low metallicity, with ionization models providing a 3σ limit of 12+log(O/H) ≤ 7.3. To explain these results, we discuss a scenario involving starburst-driven superbubbles and the creation of infalling filaments of cold gas which fuel/trigger the quasar. We also discuss the possibility of detecting large-scale absorbers such as this in emission when illuminated by a powerful quasar.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 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".