The Photometric Analysis of the Environment Around Two Dusty Star-forming Galaxies at <i>z</i> ∼ 2
Bibliographic record
Abstract
Abstract Studying the environments of dusty star-forming galaxies (DSFGs) provides insight into whether these luminous systems are reliable signposts of large-scale overdensities. Evidence suggests that individual DSFGs can trace overdense environments, although this association may not be universal. To test this, we investigate the environments surrounding two luminous, gravitationally lensed DSFGs (SDP.17b at z spec = 2.3049 and HELMS-55 at z spec = 2.2834). Using Gemini South Flamingos-2 (F2) K s -band imaging together with ancillary Subaru Hyper Suprime-Cam and Hubble Space Telescope multiband photometry, we obtain photometric redshifts, z phot , as well as star formation rates and stellar mass estimates for companion galaxies of the DSFGs. At least 5 ± 2 and 15 ± 3 companion galaxies exist with consistent z phot ( dz ≤ 0.2) within a projected separation of 5.5 cMpc of SDP.17b and HELMS-55, respectively. These correspond to galaxy overdensities of δ = 0.1 ± 0.2 and δ = 1.0 ± 0.3, with significances of (0.2 ± 0.4) σ and (2.2 ± 0.6) σ , respectively. On the M H 2 -overdensity-significance plane, HELMS-55 may follow the positive correlation between the gas mass and the overdensity significance, while SDP.17b lies well above the relation despite its large gas reservoir, making it a potential outlier. Based on this study of two DSFGs, our photometric analysis suggests that DSFGs can trace the outskirts of protoclusters or associated large-scale structures. However, our small sample prevents firm conclusions about their ability to pinpoint dense cluster cores. Future multi-object spectroscopic observations are required to confirm the membership and star formation properties of the companion 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".