Identifications of faint<i>Chandra</i>sources in the globular cluster M3
Bibliographic record
Abstract
We report a |$30\, \mathrm{ks}$|Chandra ACIS-S survey of the globular cluster M3. Sixteen X-ray sources were detected within the half-light radius (2.3 arcmin) with |$L_X \gtrsim 2.3 \times 10^{31}\, \mathrm{erg\, s^{-1}}$|. We used Hubble Space Telescope WFC3/UVIS and ACS/WFC images to find 10 plausible optical/UV counterparts. We fit the spectral energy distribution of the known cataclysmic variable (CV) 1E1339.8+2837 with a blue (|$T_\mathrm{eff} = 2.10^{+1.96}_{-0.58}\times 10^4\, \mathrm{K}$|, 90 per cent conf.) spectral component from an accretion disc, plus a red component (|$T_\mathrm{eff} = 3.75_{-0.15}^{+1.05}\times 10^3\, \mathrm{K}$|) potentially from a subgiant donor. The second brightest source (CX2) has a soft blackbody-like spectrum suggesting a quiescent low-mass X-ray binary (qLMXB) containing a neutron star. Six new counterparts have obvious UV and/or blue excesses, suggesting a CV or background active galactic nucleus (AGN) nature. Two (CX6 and CX8) have proper motions (PMs) indicating cluster membership, suggesting a CV nature. CX6 is blue in UV filters but red in V–I, which is difficult to interpret. Two CV candidates, CX7 and CX13, show blue excesses in B–V colour but were not detected in the UV. The other two CV candidates were only detected in the two UV bands (UV275 and NUV336), so do not have PM measurements, and may well be AGNs. One Chandra source can be confidently identified with a red straggler (a star reward of the giant branch). The observed X-ray source population of M3 appears consistent with its predicted stellar interaction rate.
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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 | 0.001 |
| Science and technology studies | 0.001 | 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".