Compact binary formation in open star clusters – I. High formation efficiency of Gaia BHs and their multiplicities
Bibliographic record
Abstract
ABSTRACT Gaia BHs, black hole (BH) binaries discovered from data base of an astrometric telescope Gaia, pose a question to the standard binary evolution model. We have assessed whether Gaia BHs can be formed through dynamical capture in open clusters rather than through isolated binary evolution. We have performed gravitational N-body simulations of 100 open clusters with $10^5 \, \mathrm{M}_\odot$ in total for each metallicity Z = 0.02, 0.01, and 0.005. We have discovered one Gaia BH-like binary escaping from an open cluster, and found that the formation efficiency of Gaia BHs in open clusters ($\sim 10^{-5} \, \mathrm{M}_\odot ^{-1}$) is larger than in isolated binaries ($\sim 10^{-8} \, \mathrm{M}_\odot ^{-1}$) by 3 orders of magnitude. The Gaia BH-like binary is the inner binary of a triple star system. Gaia BHs can have tertiary stars frequently, if they are formed in open clusters. Combining additional N-body simulations with 8000 open clusters with $8 \times 10^6 \, \mathrm{M}_\odot$, we have estimated the number of Gaia BHs in the Milky Way disc to 104–105 (depending on the definitions of Gaia BHs), large enough for the number of Gaia BHs discovered so far. Our results indicate that the discoveries of Gaia BHs do not request the reconstruction of the standard binary evolution model, and that Gaia BHs are a probe for the dynamics of open clusters already evaporated.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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 teacher head, 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".