The Structural Evolution of Substructure
Bibliographic record
Abstract
We investigate the evolution of substructure in cold dark matter (CDM) halos using N -body simulations of tidal stripping of substructure halos within a static host potential. We find that halos modeled following the Navarro, Frenk, & White (NFW) mass profile lose mass continuously because of tides from the massive host, leading to the total disruption of satellite halos with small tidal radii. Although mass is predominantly stripped from the outer regions, tidal heating also causes the halo to expand and the central density to decrease after each pericentric passage, when mass loss preferentially occurs. As a result, simple models based on the tidal-limit approximation underestimate significantly the tidal mass loss over several orbits. The equilibrium structure of stripped NFW halos depends mainly on the fraction of mass lost and can be expressed in terms of a simple correction to the original NFW profile. We apply these results to substructure in the Milky Way and conclude that the dark matter halos surrounding its dwarf spheroidal (dSph) satellites have circular velocity curves that peak well beyond the luminous radius at velocities significantly higher than expected from the stellar line-of-sight velocity dispersion. Our modeling suggests that the true tidal radii of dSphs lie well beyond the putative tidal cutoff observed in the surface brightness profile, suggesting that the latter are not really tidal in origin but rather features in the light profile of limited dynamical relevance. For Draco in particular, our modeling implies that its tidal radius is much larger than derived by Irwin & Hatzidimitriou, lending support to the interpretation of recent Sloan Digital Sky Survey data by Odenkirchen et al. Similarly, our model suggests that Carina's halo has a peak circular velocity of order ~55 km s -1 , which may help explain how this small galaxy has managed to retain enough gas to undergo several bursts of star formation. Our results imply a close correspondence between the most massive substructure halos expected in a CDM universe and the known satellites of the Milky Way and suggest that only substructure halos with peak circular velocities below 35 km s -1 lack readily detectable luminous counterparts.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".