The formation and evolution of bars in low surface brightness galaxies with cold dark matter haloes
Bibliographic record
Abstract
We perform several high-resolution simulations of low surface brightness galaxies (LSBGs) embedded in cold dark matter haloes to study how likely bar formation is in such systems. The behaviour of various collisionless galaxy models is studied both in isolation and in the presence of a large perturbing satellite. We also consider models with a dominant gaseous component in the disc. We find that in general bar formation requires disc masses at least a factor of 2 higher than those inferred for LSBGs under the assumption of a normal stellar mass-to-light ratio. Instead, if LSBGs have fairly light, low surface density discs, they are stable to the formation of a stellar bar within NFW (Navarro–Frenk–White) haloes spanning a range of concentrations. However, a purely gaseous light disc can form a bar for realistic temperatures provided that cooling is very efficient (we adopt an isothermal equation of state) and that the halo has a very low concentration, c < 5. The bars that form in these low surface brightness (LSB) models are significantly shorter than the typical halo scale radius — their overall angular momentum content might be too low to affect significantly the inner dark halo structure. Once formed, all the bars evolve into bulge-like structures in only a few gigayears and can excite spiral patterns in the surrounding disc component. The recently discovered red LSBGs show significant non-axisymmetric structure and bulge-like components, and share many of their structural properties with the final states of our LSB models with massive discs. Our results imply that a bulge-like component must be present in any LSBG that ever went bar-unstable in the past.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 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".