Dark subhaloes and disturbances in extended H i discs
Bibliographic record
Abstract
We develop a perturbative approach to study the excitation of disturbances in the extended atomic hydrogen (H I) discs of galaxies produced by passing dark matter subhaloes. The shallow gravitational potential of the dark matter subhaloes (compared to the primary halo) allows us to use the epicyclic approximation, the equations of which we solve by modal analysis, that is, assuming a disc is composed of N radial rings with M modes. We show that properties of dark matter subhaloes can be inferred from the profile and amplitude of the modal energy of the disc. Namely, we find that the overall amplitude of the response gives the mass of the dark subhalo. Motivated by this modal analysis, we then show that the density response shows similar features. Finally, we show that our results agree with those from full hydrodynamic simulations. We find a simple scaling relation between the satellite mass and the low-order Fourier amplitudes of the resultant surface density of the gas disc where the effective Fourier amplitude (essentially a sum over the low-order modes) scales as m 1/2 s , where m s is the satellite mass. The utility of this relation is that it can be readily applied to an observed H I map to deduce the satellite mass without recourse to full numerical simulations. This will greatly aid us in analysing large samples of spiral galaxies to constrain the population of dwarf satellites in the Local Volume.
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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 | 0.001 |
| 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".