A radio continuum and polarization study of the pulsar wind nebula CTB 87 (G74.9+1.2)
Bibliographic record
Abstract
ABSTRACT We present radio continuum and linear polarization observations of the pulsar wind nebula (PWN) CTB 87 (G74.9+1.2) with the Effelsberg 100-m Radio Telescope between 4.75 and 32 GHz. An analysis of these new data including archived low-frequency observations at 1420 and 408 MHz from the Canadian Galactic Plane Survey shows that CTB 87 consists of two distinct emission components: a compact kidney-shaped component, 14 × 8.5 pc2 (7.8 × 4.8 arcmin2) in size and a larger diffuse, spherical, and centrally peaked component of about 30 pc (17 arcmin) in diameter. The kidney-shaped component with a much steeper radio continuum spectrum is highly linearly polarized and likely represents a relic PWN. The diffuse component represents the undisturbed part of the PWN expanding inside a cavity or stellar wind bubble. The previously reported spectral break above 10 GHz is likely the result of missing large-scale emission and insufficient sensitivity of the high-frequency radio continuum observations. The simulation of the system’s evolution yields an age of about 18 000 yr as the result of a Type II supernova explosion with ejecta mass of about 12 M⊙ and explosion energy of about 7 × 1050 erg. We also found evidence for a radio shell in our polarization data that represents the blast wave that entered the molecular cloud complex at a radius of about 13 pc.
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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".