Bibliographic record
Abstract
The spatial distribution of the Galactic satellite system plays an important role in Galactic dynamics and cosmology, where its successful reproduction is a key test of simulations of galaxy halo formation. Here, we examine its representative nature by conducting an analysis of the three-dimensional spatial distribution of the M31 subgroup of galaxies, the next closest system to our own. We begin by a discussion of distance estimates and incompleteness concerns, before revisiting the question of membership of the M31 subgroup. We constrain this by consideration of the spatial and kinematic properties of the putative satellites. Comparison of the distribution of M31 and Galactic satellites relative to the galactic discs suggests that the Galactic system is probably modestly incomplete at low latitudes by ≃20 per cent. We find that the radial distribution of satellites around M31 is more extended than the Galactic subgroup; 50 per cent of the Galactic satellites are found within ∼100 kpc of the Galaxy, compared to ∼200 kpc for M31. We search for ‘ghostly streams’ of satellites around M31, in the same way others have done for the Galaxy, and find several, including some that contain many of the dwarf spheroidal satellites. The lack of M31-centric kinematic data, however, means that we are unable to probe whether these streams represent real physical associations. Finally, we find that the M31 satellites are asymmetrically distributed with respect to our line of sight to this object, so that the majority of its satellites are on its near side with respect to our line of sight. We quantify this result in terms of the offset between M31 and the centre of its satellite distribution, and find it to be significant at the ∼ 3σ level. We discuss possible explanations for this finding, and suggest that many of the M31 satellites may have been accreted only relatively recently. Alternatively, this anisotropy may be related to a similar result recently reported for the 2dFGRS, which would imply that the halo of M31 is not yet virialized. Until such time as a satisfactory explanation for this finding is presented, however, our results warn against treating the M31 subgroup as complete, unbiased and relaxed.
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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 | 0.000 | 0.000 |
| 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".