Two distant brown dwarfs in the UKIRT Infrared Deep Sky Survey Deep Extragalactic Survey Data Release 2
Bibliographic record
Abstract
We present the discovery of two brown dwarfs in the UK infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Deep Extragalactic Survey (DXS) Data Release 2 (DR2). Both objects were selected photometrically from 6 deg2 in DXS for their blue J−K colour and the lack of optical counterparts in the Sloan Digital Sky Survey (SDSS) Stripe 82. Additional optical photometry provided by the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) corroborated the possible substellarity of these candidates. Subsequent methane imaging of UDXS J221611.51+003308.1 and UDXS J221903.10+002418.2 has confirmed them as T7 ± 1 and T6 ± 1 dwarfs at photometric distances of 81 (52–118 pc) and 60 (44–87 pc; 2σ confidence level). A similar search in the DR2 of the Ultra-Deep Survey over a smaller area (0.77 deg2) and shallower depth did not return any late-T dwarf candidate. The numbers of late-T dwarfs in our study are broadly in line with a declining mass function when considering the current area and depth of the DXS and UDS. These brown dwarfs are the first discovered in the Visible Imaging Multi-Object Spectrograph (VIMOS) 4 field and among the few T dwarfs found in pencil-beam surveys. They are valuable to investigate the scaleheight of T dwarfs.
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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 | 0.001 | 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".