Low-redshift 21cm Cosmology in Canada
Bibliographic record
Abstract
Line-intensity mapping of the 21cm line is a powerful probe of large scale structure at z<6, tracing large-scale structure via neutral hydrogen content that is found within galaxies. In principle, it enables cost-efficient surveys of the matter distribution up to z~6, unlocking orders of magnitude more modes for observational cosmology. Canada has been a traditional leader in this field, having led the first detections of the cosmological 21cm signal via cross-correlations with optical galaxy surveys and having constructed the Canadian Hydrogen Intensity Mapping Experiment (CHIME). The field is now entering a new era where data is abundant, allowing studies in how to overcome systematics to be tackled in an empirical, head-on fashion. In the next few years, this will produce the first detection of the 21cm auto power spectrum, which will pave the way towards a large suite of scientific possibilities. These potentially include precision measurements on the dark energy equation of state and other LCDM parameters, constraints on how HI mass traces dark matter, a detection of neutrino effects on large-scale structure, and the use of 21cm lensing to further constrain cosmology. To turn these promising directions into reality, we recommend a sustained program of investment in 21cm cosmology, starting with funding for the Canadian Hydrogen Observatory and Radio transient Detector (CHORD), followed by small-scale development efforts targeting next-generation hardware and sustained support for theory and technical staff support. Additionally, Canada should invest in complementary line-intensity mapping efforts (such as with CO or [CII] lines) and maintain participation in next-generation international efforts such as the Packed Ultra-wideband Mapping Array (PUMA) and the Square Kilometre Array (SKA).
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".