H I SHELLS AND SUPERSHELLS IN THE I-GALFA H I 21 cm LINE SURVEY. I. FAST-EXPANDING H I SHELLS ASSOCIATED WITH SUPERNOVA REMNANTS
Bibliographic record
Abstract
We search for fast-expanding H i shells associated with Galactic supernova remnants (SNRs) in the longitude range ℓ ≈ 32° to 77° using 21 cm line data from the Inner-Galaxy Arecibo L -band Feed Array (I-GALFA) H i survey. Among the 39 known Galactic SNRs in this region, we find such H i shells in 4 SNRs: W44, G54.4–0.3, W51C, and CTB 80. All four were previously identified in low-resolution surveys, and three of those (excluding G54.4–0.3) were previously studied with the Arecibo telescope. A remarkable new result, however, is the detection of H i emission at both very high positive and negative velocities in W44 from the receding and approaching parts of the H i expanding shell, respectively. This is the first detection of both sides of an expanding shell associated with an SNR in H i 21 cm emission. The high-resolution I-GALFA survey data also reveal a prominent expanding H i shell with high circular symmetry associated with G54.4–0.3. We explore the physical characteristics of four SNRs and discuss what differentiates them from other SNRs in the survey area. We conclude that these four SNRs are likely the remnants of core-collapse supernovae interacting with a relatively dense (≳ 1 cm −3 ) ambient medium, and we discuss the visibility of SNRs in the H i 21 cm line.
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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 | 0.000 | 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".