Searching for Axion Dark Matter Gegenschein of the Vela Supernova Remnant with FAST
Bibliographic record
Abstract
Abstract Axions are one of the leading dark matter candidates. If we are embedded in a Milky Way dark matter halo comprised of axions, their stimulated decay would enable us to observe a counterimage (“axion gegenschein”) with a frequency equal to half the axion mass in the opposite direction of a bright radio source. This spectral line emission will be broadened to Δν/ν ∼ σ d /c ∼ 10−3 due to the velocity dispersion of dark matter, σ d . In this pilot study, we perform the first search for the expected axion gegenschein image of Vela supernova remnant with 26.4 hr of effective ON–OFF data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) L-band (1.0–1.5 GHz) 19 beam receiver. Our null detection limits the axion–photon coupling strength to be g aγγ ≲ 2 × 10−10 GeV−1 in the mass ranges of 8.7 μeV ≤ m a ≤ 9.44 μeV and 10.85 μeV ≤ m a ≤ 12.01 μeV. These results provide a stronger constraint on g aγγ in this axion mass range than the current limits obtained by the direct search of an axion decay signal from a dwarf galaxy that uses FAST observations, but are a factor of ∼3 times weaker than the current CERN Axion Solar Telescope limit. Based on our observation strategy, data processing methods, and results, the expected sensitivity will reach ∼10−11 GeV−1 with ∼2000 hr of observation in the future.
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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 | 0.001 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".