The Atacama Cosmology Telescope: DR4 maps and cosmological parameters
Bibliographic record
Abstract
<p>We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from the Atacama Cosmology Telescope, using data taken from 2013&ndash;2016 at 98 and 150 GHz. The maps cover more than 17,000 deg<sup>2</sup>, the deepest 600 deg<sup>2</sup>&nbsp;with noise levels below&nbsp;10&mu;K-arcmin. We use the power spectrum derived from almost 6,000 deg<sup>2</sup>&nbsp;of these maps to constrain cosmology. The ACT data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. From these one can derive the distance to the last-scattering surface and thus infer the local expansion rate,&nbsp;<em>H</em><sub>0</sub>. By combining ACT data with large-scale information from&nbsp;<em>WMAP</em>&nbsp;we measure&nbsp;<em>H</em><sub>0</sub>=67.6&plusmn;&nbsp;1.1&nbsp;km/s/Mpc, at 68% confidence, in excellent agreement with the independently-measured&nbsp;<em>Planck</em>&nbsp;satellite estimate (from ACT alone we find&nbsp;<em>H</em><sub>0</sub>=67.9&plusmn;&nbsp;1.5&nbsp;km/s/Mpc). The&nbsp;&Lambda;CDM model provides a good fit to the ACT data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1&sigma;; the number of relativistic species, the primordial Helium fraction, and the running of the spectral index are consistent with&nbsp;&Lambda;CDM predictions to within 1.5&ndash;2.2&sigma;. We compare ACT,&nbsp;<em>WMAP</em>, and&nbsp;<em>Planck</em>&nbsp;at the parameter level and find good consistency; we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding CMB large-scale information that ACT does not measure. The DR4 products presented here will be publicly released on the NASA Legacy Archive for Microwave Background Data Analysis.</p>
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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.021 | 0.008 |
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".