The SWELLS survey - I. A large spectroscopically selected sample of edge-on late-type lens galaxies
Bibliographic record
Abstract
The relative contribution of baryons and dark matter to the inner regions of spiral galaxies provides critical clues to their formation and evolution, but it is generally difficult to determine. For spiral galaxies that are strong gravitational lenses, however, the combination of lensing and kinematic observations can be used to break the disc–halo degeneracy. In turn, such data constrain fundamental parameters such as (i) the mass density profile slope and axial ratio of the dark matter halo, and by comparison with dark matter-only numerical simulations the modifications imposed by baryons; (ii) the mass in stars and therefore the overall star formation efficiency, and the amount of feedback; (iii) by comparison with stellar population synthesis models, the normalization of the stellar initial mass function. In this first paper of a series, we present a sample of 16 secure, one probable and six possible strong lensing spiral galaxies, for which multiband high-resolution images and rotation curves were obtained using the Hubble Space Telescope and Keck II telescope as part of the Sloan WFC Edge-on Late-type Lens Survey (SWELLS). The sample includes eight newly discovered secure systems. We characterize the sample of deflector galaxies in terms of their morphologies, structural parameters and stellar masses. We find that the SWELLS sample of secure lenses spans a broad range of morphologies (from lenticular to late-type spiral), spectral types (quantified by Hα emission) and bulge to total stellar mass ratio (0.22–0.85), while being limited to M* > 1010.5 M⊙. The SWELLS sample is thus well suited for exploring the relationship between dark and luminous matter in a broad range of galaxies. We find that the deflector galaxies obey the same size–mass relation as that of a comparison sample of elongated non-lens galaxies selected from the Sloan Digital Sky Survey. We conclude that the SWELLS sample is consistent with being representative of the overall population of high-mass high-inclination discy galaxies.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".