On the Detectability of Visible-wavelength Line Emission from the Local Circumgalactic and Intergalactic Medium
Bibliographic record
Abstract
Abstract We describe a new approach to studying the intergalactic and circumgalactic medium in the local universe: direct detection through narrowband imaging of ultralow surface brightness visible-wavelength line emission. We use the hydrodynamical cosmological simulation EAGLE to investigate the expected brightness of this emission at low redshift ( z ≲ 0.2). H α emission in extended halos (analogous to the extended Ly α halos/blobs detected around galaxies at high redshifts) has a surface brightness of ≳700 photons cm −2 sr −1 s −1 out to ∼100 kpc. Mock observations show that the Dragonfly Telephoto Array, equipped with state-of-the-art narrowband filters, could directly image these structures in exposure times of ∼10 hr. H α fluorescence emission from this gas can be used to place strong constraints on the local ultraviolet background and on gas flows around galaxies. Detecting H α emission from the diffuse intergalactic medium (the “cosmic web”) is beyond current capabilities but would be possible with a hypothetical 1000-lens Dragonfly array.
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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 | 0.000 | 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".