DETECTION OF HF TOWARD PKS 1830–211, SEARCH FOR INTERSTELLAR H<sub>2</sub>F<sup>+</sup>, AND LABORATORY STUDY OF H<sub>2</sub>F<sup>+</sup> AND H<sub>2</sub>Cl<sup>+</sup> DISSOCIATIVE RECOMBINATION
Bibliographic record
Abstract
ABSTRACT We report extragalactic observations of two fluorine-bearing species, hydrogen fluoride (HF) and fluoronium (H 2 F + ), in the z = 0.89 absorber in front of the lensed blazar PKS 1830−211 with the Atacama Large Millimeter/submillimeter Array. HF was detected toward both southwest and northeast images of the blazar, with column densities >3.4 × 10 14 cm −2 and 0.18 × 10 14 cm −2 , respectively. H 2 F + was not detected, down to an upper limit (3 σ ) of 8.8 × 10 11 cm −2 and an abundance ratio of [H 2 F + ]/[HF] 1/386. We also searched for H 2 F + toward the Galactic sources NGC 6334 I and W51C, and toward Galactic center clouds with the Herschel HIFI spectrometer. 6 The upper limit on the column density was derived to be 2.5 × 10 11 cm −2 in NGC 6334 I, which is 1/68 of that for H 2 Cl + . In constrast, the ortho transition of H 2 Cl + is detected toward PKS 1830–211. To understand the small abundance of interstellar H 2 F + , we carried out laboratory experiments to determine the rate constants for the ion–electron recombination reaction by infrared time-resolved spectroscopy. The constants determined are k e (209 K) = cm 3 s −1 and cm 3 s −1 for H 2 F + and H 2 Cl + , respectively. The difference in the dissociative recombination rates between H 2 F + and H 2 Cl + by a factor ∼2 and the cosmic abundance ratio [F]/[Cl] ≈ 1/6 are not enough to explain the much smaller abundance of H 2 F + . The difference in the formation mechanism of H 2 F + and H 2 Cl + in interstellar space would be a major factor in the small abundance of H 2 F + .
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How this classification was reachedexpand
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".