THE SIGNATURE OF GALACTIC TIDES IN LOCAL GROUP DWARF SPHEROIDALS
Bibliographic record
Abstract
(Abridged) We use N-body simulations to explore the effects of tidal stripping on the structure of dwarf spheroidal galaxies (dSphs). We model dSphs as King spheres embedded in NFW dark halos that orbit the Galactic potential on eccentric orbits. We find that episodes of stellar mass loss remove the initial cutoff of the bound stellar core. Once equilibrium has been re-established the outer mass profile approaches a power-law in projection that is well described by a simple Plummer model. Tides also result in transient features in the outer density profile. As the system re-equilibrates, an outward-moving "excess" of stars is found at radii where the local crossing time exceeds the time elapsed since pericenter. If the orbit is known, these results provide a simple way to assess whether "breaks" and "bumps" in the profile of dSphs are actually tidal in origin. We apply this to the Sagittarius dwarf and, encouragingly, identify two features in the profile that may be traced to its two last pericentric passages. Applied to Leo I, we find that any tidal break would locate beyond the area surveyed by current data, casting doubt on recent claims of the detection of tidal debris around this galaxy. For Carina, the tidal break should occur at a radius twice farther than observed, suggesting that the outer excess of stars is not tidal in origin unless its orbit is in error. A similar comment applies to Sculptor, whose pericenter appears too large for Galactic tides to be important but whose outer profile, like that of Draco, nonetheless follows closely a Plummer-law. Fornax and Leo II show no sign of a power-law outer profile, suggesting that they have not suffered stellar tidal stripping. Published profiles for other, fainter Milky Way dSph companions do not extend sufficiently far to allow for conclusive assessment.
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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 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".