The Dragonfly Edge-on Galaxies Survey: Shaping the Outer disk of NGC 4565 via Accretion
Bibliographic record
Abstract
Abstract We present deep g- and r-band imaging of the well-known edge-on galaxy NGC 4565 (the “Needle Galaxy”), observed as part of the Dragonfly Edge-on Galaxies Survey. The 3σ local surface brightness contrast limit on 10″ scales is 28.616 ± 0.005 mag arcsec−2 for the r-band image and 28.936 ± 0.005 mag arcsec−2 for the g-band image. We trace the galaxy’s starlight in narrow slice profiles spanning over 90 kpc along the major axis (with bin sizes ranging from 1.7 × 0.5 to 1.7 × 7.8 kpc) to surface brightnesses below 29 mag arcsec−2. We confirm the previously observed asymmetric disk truncation in NGC 4565. In addition, the sharp northwest truncation turns over to a shallower component that coincides with a fan-like feature seen to wrap around the northwest disk limb. We propose that the fan may be a tidal ribbon and qualitatively replicate the fan with simple simulations, although alternative explanations of the fan and the disk’s asymmetry are shown to be possible. In any case, we conclude that there is strong evidence for accretion-based outer disk growth in NGC 4565.
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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 | 0.001 |
| 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".