The Boomerang PWN G106.6+2.9 and the Magnetic Field Structure in Pulsar Wind Nebulae
Bibliographic record
Abstract
We present new observations at high radio frequencies made with the Effelsberg 100 m radio telescope of the "Boomerang" pulsar wind nebula (PWN) G106.65+2.96, which is part of the supernova remnant (SNR) G106.3+2.7. Including low-frequency data from the Canadian Galactic Plane Survey allows us to develop a complete picture of the PWN and its evolution in a very complex environment. The radio continuum spectrum reveals a break between 4 and 5 GHz that is the result of synchrotron cooling. We find evidence that the reverse shock of the initial supernova shock wave has driven away the original PWN, which explains why the current nebula around the pulsar has such a low radio luminosity. An analysis of the energy budget of the pulsar, the magnetic field in the nebula, and the lifetime of relativistic electrons gives a magnetic field of 2.6 mG in the PWN with an age of 3900 yr. This is not the age of the SNR but the time that has passed since the reverse shock crushed the original PWN. A comparison of our polarization measurements with those of other PWNe leads to a simple model of the magnetic field structure within such an object. Using this model, we derive an angle of about 30° between the Galactic north and the spin axis of the pulsar, projected onto the plane of the sky. The spin axis is pointing away from us, toward the northwest. This agrees nicely with the results of Ng and Romani, who in a 2004 paper calculated an angle of 20° from their fits of a model torus to a Chandra measurement of the Boomerang. The nebula contains a toroidal magnetic field structure, yet the rotation measure distribution indicates a radial magnetic field as its cause. Apparently, the observed radio emission originates on the far side of the object and passes through the inner region, which has a radial magnetic field.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".