New black hole spin values for Sagittarius A* obtained with the outflow method
Bibliographic record
Abstract
ABSTRACT Six archival Chandra observations are matched with eight sets of radio data and studied in the context of the outflow method to measure and study the spin properties of $\rm {Sgr ~A^{*}}$. Three radio and X-ray data sets obtained simultaneously, or partially simultaneously, are identified as preferred for the purpose of measuring the spin properties of $\rm {Sgr ~A^{*}}$. Similar results are obtained with other data sets. Results obtained with the preferred data sets are combined and indicate weighted mean values of the spin function of $F = 0.62 \pm 0.10$ and dimensionless spin angular momentum of $a_* = 0.90 \pm 0.06$. The spin function translates into measurements of the black hole rotational mass, Mrot, irreducible mass, Mirr, and spin mass–energy available for extraction, Mspin, relative to the total black hole dynamical mass, Mdyn. Weighted mean values of (Mrot/Mdyn) = (0.53 ± 0.06), (Mirr/Mdyn) = (0.85 ± 0.04), (Mspin/Mdyn) = (0.15 ± 0.04), Mrot = (2.2 ± 0.3) × 106 M⊙, Mirr = (3.5 ± 0.2) × 106 M⊙, and Mspin = (6.2 ± 1.6) × 105 M⊙ are obtained; of course (Mrot/Mirr) = (0.62 ± 0.10) since (Mrot/Mirr) = F. Values obtained for $\rm {Sgr ~A^{*}}$ are compared with those obtained for M87 based on the published spin function, which indicate that M87 carries substantially more rotational energy and spin mass–energy relative to the total (i.e. dynamical) black hole mass, the irreducible black hole mass, and in absolute terms.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 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".