ELAIS-N1 deep field uGMRT Band-2: constraints on diffuse Galactic synchrotron emission power spectrum
Bibliographic record
Abstract
ABSTRACT We present high sensitivity, low radio frequency continuum observations of the ELAIS-N1 field with 32 h of observations of the uGMRT (upgraded Giant Meterwave Radio Telescope) Band-2 ($120-250$ MHz) covering $5.86\, \rm{deg}^2$ area, achieving a central off-source RMS noise of $237\, \mu \mathrm{Jy}\,\mathrm{beam}^{-1}$ with a resolution of $11.45\,\mathrm{ arcsec}$ at the central frequency of 183 MHz. A radio source catalogue of 1027 sources statistically matches with similar observations at different frequencies within the sensitivity range of the uGMRT. The calibrated data are further used to characterize the dominant foreground, the diffuse Galactic synchrotron emission (DGSE), in angular scale and frequency regime. We derived the angular power spectrum (APS) of DGSE in two ways: image-based estimator (i-APS) and visibility-based Tapered Gridded Estimator (TGE; hereafter as t-APS). We assess the characteristics of DGSE with a power-law form of $C_{\ell } = A({1000}/{\ell })^{\beta }$. Combining data from Band-2 and earlier Band-3 observations, we derived a spectral variation of $C_{\ell }$ in the form of $C_{\ell } = A{\nu ^{-2{\alpha }}}{\ell ^{-{\beta }}}$. Our result indicates a spectral break at $\nu = 230\, {\pm }\, 5$ MHz, corresponding to a synchrotron age of $t_\rm{syn} = 106\, {\pm }\, 1$ Myr for the cosmic-ray electrons (CRe). This break result suggests a low-energy cut-off in the CRe population, leading to spectral curvature at low frequencies. Using both of the techniques, i-APS and t-APS, we find that the mean spectral index $\alpha$ and power-law index $\beta$ are consistent within the frequency range $120-500$ MHz.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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) | 0.001 | 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".