LONG-TERM X-RAY CHANGES IN THE EMISSION FROM THE ANOMALOUS X-RAY PULSAR 4U 0142+61
Bibliographic record
Abstract
We present results obtained from X-ray observations of the anomalous X-ray pulsar (AXP) 4U 0142+61 taken between 2000 and 2008 using XMM-Newton , Chandra , and Swift . These observations coincide with periods of long-term changes and burst epochs previously reported using the Rossi X-ray Timing Explorer ( RXTE ). In observations taken before 2006, we find that the pulse profile became more sinusoidal and the pulsed fraction increased with time. These results confirm those derived using RXTE and expand the observed evolution to energies below 2 keV. The total flux in the 0.5–10 keV band determined with XMM-Newton is observed to be nearly constant in observations taken before 2006, while an increase of ∼10% is seen afterwards and coincides with the burst activity detected from the source in 2006–2007. After these bursts, the evolution toward more sinusoidal pulse profiles ceased while the flux and pulsed fraction returned to pre-bursts levels. No evidence for large-scale, long-term changes in the emission as a result of the bursts is seen. We also report on observations taken with the Gemini telescope after two bursts which show source magnitudes consistent with previous measurements. Our results demonstrate the wide range of X-ray variability characteristics seen in AXPs and we discuss them in light of current emission models for these sources.
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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 | 0.000 | 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".