OBSERVATIONS AND MODELING OF RELATIVISTIC SPIN PRECESSION IN PSR J1141–6545
Bibliographic record
Abstract
Observations of the binary pulsar PSR J1141−6545 using the Parkes radio telescope over 9.3 yr show clear time variations in pulse width, shape, and polarization. We interpret these variations in terms of relativistic precession of the pulsar spin axis about the total angular momentum vector of the system changing our view of the emission beam. Over those nine years, the pulse width at the 50% level has changed by more than a factor of 3, reaching a maximum value of nearly 13° in early 2007. Large variations have also been observed in the 1400 MHz mean flux density; this reached a peak of ∼20 mJy in mid-2002 but over the past several years has been relatively steady at ∼3 mJy. The pulse polarization has been monitored since 2004 April using digital filterbank systems and also shows large and systematic variations in both linear and circular polarization. Position angle (P.A.) variations, both across the pulse profile and over the data span, are complex, with major differences between the central and outer parts of the pulse profile. We interpret the outer parts as representing the underlying magnetic field and fit the rotating-vector model to these regions. Modeling of the observed P.A. variations by relativistic precession of the pulsar spin axis shows that the spin–orbit misalignment angle is about 110° and that the precessional phase has passed through 180° during the course of our observations. At the start of our observations, the line-of-sight impact parameter was about 4° in magnitude and it reached a minimum very close to 0° around early 2007, consistent with the observed pulse width variations. We have therefore mapped approximately one half of the emission beam, at least out to a radius of about 4°, showing that it is very asymmetric with respect to the magnetic axis. The derived precessional parameters imply that the pre-supernova (pre-SN) star had a mass of about 2 M ☉ and that the SN recoil kick velocity was relatively small, between 100 and 250 km s −1 , depending on the assumed systemic velocity. With the reversal in the rate of change of the impact parameter, we predict that over the next decade we will see a reversed "replay" of the variations observed in the past decade.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 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".