Eight New Millisecond Pulsars in NGC 6440 and NGC 6441
Bibliographic record
Abstract
Motivated by the recent discovery of 30 new millisecond pulsars in Terzan 5, made using the Green Bank Telescope's S-band receiver and the Pulsar Spigot spectrometer, we have set out to use the same observing system in a systematic search for pulsars in other globular clusters. Here we report on the discovery of five new pulsars in NGC 6440 and three in NGC 6441; each cluster previously had one known pulsar. Using the most recent distance estimates to these clusters, we conclude that there are as many potentially observable pulsars in NGC 6440 and NGC 6441 as in Terzan 5. We present timing solutions for all of the pulsars in these globular clusters. Four of the new discoveries are in binary systems; one of them, PSR J1748–2021B (NGC 6440B), has a wide ( P b = 20.5 days) and eccentric ( e = 0.57) orbit. This allowed a measurement of its rate of advance of periastron, = 0.00391(18)° yr −1 . If this is a purely relativistic effect, the total mass of this binary system is 2.92 ± 0.20 M ☉ (1 σ) implying a median pulsar mass of 2.74 ± 0.21 M ☉ . There is a 1% probability that the inclination is low enough that pulsar mass is below 2 M ☉ , and 0.10% probability that it is between 1.20 and 1.44 M ☉ . If confirmed, this anomalously large mass would strongly constrain the equation of state for dense matter. The other highly eccentric binary, PSR J1750–37A, has e = 0.71, and = 0.0055(3)° yr −1 , implying a total system mass of 1.97 ± 0.15 M ☉ and, along with the mass function, maximum and median pulsar masses of 1.65 and 1.26 M ☉ , respectively.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".