Interstellar anatomy of the TeV gamma-ray peak in the IC443 supernova remnant
Bibliographic record
Abstract
Context. Supernova remnants (SNRs) represent a major feedback source from stars in the interstellar medium of galaxies. During the latest stage of supernova explosions, shock waves produced by the initial blast modify the chemistry of gas and dust, inject kinetic energy into the surroundings, and may alter star formation characteristics. Simultaneously, γ -ray emission is generated by the interaction between the ambient medium and cosmic rays (CRs), including those accelerated in the early stages of the explosion. Aims. We study the stellar and interstellar contents of IC443, an evolved shell-type SNR at a distance of 1.9 kpc with an estimated age of 30 kyr. We aim to measure the mass of the gas and characterize the nature of infrared point sources within the extended G region, which corresponds to the peak of γ -ray emission detected by VERITAS and Fermi . Methods. We performed 10′ × 10′ mapped observations of 12 CO, 13 CO J = 1–0, J = 2–1, and J = 3–2 pure rotational lines, as well as C 18 O J = 1–0 and J = 2–1 obtained with the IRAM 30 m and APEX telescopes over the extent of the γ -ray peak to reveal the molecular structure of the region. We first compared our data with local thermodynamic equilibrium models. We estimated the optical depth of each line from the emission of the isotopologs 13 CO and C 18 O. We used the population diagram and large velocity gradient assumption to measure the column density, mass, and kinetic temperature of the gas using 12 CO and 13 CO lines. We used complementary data (stars, gas, and dust at multiple wavelengths) and infrared point source catalogs to search for protostar candidates. Results. Our observations reveal four molecular structures: a shocked molecular clump associated with emission lines extending between −31 and 16 km s −1 , a quiescent, dark cloudlet associated with a line width of ~2 km s −1 , a narrow ring-like structure associated with a line width of ~1.5 km s −1 , and a shocked knot. We measured a total mass of ~230, ~90, ~210, and ~4 M ⊙ , respectively, for the cloudlet, ring-like structure, shocked clump, and shocked knot. We measured a mass of ~1100 M ⊙ throughout the rest of the field of observations where an ambient cloud is detected. We found 144 protostar candidates in the region. Conclusions. Our results emphasize how the mass associated with the ring-like structure and the cloudlet cannot be overlooked when quantifying the interaction of CRs with the dense local medium. Additionally, the presence of numerous possible protostars in the region might represent a fresh source of CRs, which must also be taken into account in the interpretation of γ -ray observationsin this region.
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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 | 0.000 | 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 | 0.001 | 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 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".