THE SPIN-DOWN OF SWIFT J1822.3–1606: A NEW GALACTIC MAGNETAR
Bibliographic record
Abstract
On 2011 July 14, a new magnetar candidate, Swift J1822.3−1606, was identified via a rate trigger on the Swift /Burst Alert Telescope. Here we present an initial analysis of the X-ray properties of the source, using data from the Rossi X-ray Timing Explorer , Swift , and the Chandra X-ray Observatory , spanning 2011 July 16–October 8. We measure a precise spin period of P = 8.43771968(6) s and a spin-down rate of , at MJD 55761.0, corresponding to an inferred surface dipole magnetic field of B = 4.7(2) × 10 13 G, the second lowest thus far measured for a magnetar, though similar to those of 1E 2259+586 and several high-magnetic field radio pulsars. We show that the flux decay in the 1–10 keV band is best fit by a double exponential with timescales of 9 ± 1 and 55 ± 9 days. The pulsed count rate decay in the 2–10 keV band, by contrast, is better fit by a single exponential decay with timescale 15.9 ± 0.2 days. After increasing from ∼35% for ∼20 days after the onset of the outburst, the pulsed fraction in the 2–10 keV band remained constant at ∼45%. We argue that these properties confirm this source to be a new member of the class of objects known as magnetars. We consider the distribution of magnetar periods and inferred dipole magnetic field strengths, showing that the former appears flat in the 2–12 s range, while the latter appears peaked in the 10 14 –10 15 G range.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".