MAGIC GAMMA-RAY TELESCOPE OBSERVATION OF THE PERSEUS CLUSTER OF GALAXIES: IMPLICATIONS FOR COSMIC RAYS, DARK MATTER, AND NGC 1275
Bibliographic record
Abstract
The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hours during November and December 2008. The resulting upper limits on the γ-ray emission above 100 GeV are in the range of 4.6 to 7.5 × 10−12 cm−2 s−1 for spectral indices from −1.5 to −2.5 ; thereby constraining the emission produced by cosmic rays, dark matter annihilations and the central radio galaxy NGC 1275. Results are compatible with cosmological cluster simulations for the cosmic ray induced γ-ray emission, constraining the average cosmic ray-to-thermal pressure to < 4% for the cluster core region (< 8% for the entire cluster). Using simplified assumptions adopted in earlier work (a power-law spectrum with an index of −2.1, constant cosmic ray-to-thermal pressure for the peripheral cluster regions while accounting for the adiabatic contraction during the cooling flow formation), we would limit the ratio of cosmic ray-to-thermal energy to ECR /Eth < 3%. Improving the sensitivity of this observation by a factor of about seven will enable us to scrutinize the hadronic model for the Perseus radio mini halo: a non-detection of γ-ray emission at this level implies cosmic rays fluxes that are too small to produce enough electrons through hadronic interactions with the ambient gas protons to explain the observed synchrotron emission. The upper limit also translates into a level of γ-ray emission from possible annihilations of the cluster dark matter (the dominant mass component) that is consistent with boost factors of ∼ 104 for the typically expected dark matter annihilation induced emission. Finally, the upper limits obtained for the γ-ray emission of the central radio galaxy NGC 1275 are consistent with the recent detection by the Fermi-LAT satellite. Due to the extremely large Doppler factors required for the jet, a one-zone synchrotron self-Compton model is implausible in this case. We reproduce the observed spectral energy density by using the structured jet (spine-layer) model which has previously been adopted to explain the high-energy emission of radio galaxies.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".