Astrophysics · arXiv:astro-ph/0402322 v2 · submitted 13 Feb 2004
The 21 centimeter emission from the reionization epoch: extended and point source foregrounds
The paper says
“Hence, efficient source removal may be sufficient to allow the detection of angular fluctuations in the 21cm emission free of extragalactic foregrounds at \theta > 1 arcmin.”
from the abstract · picked out as the main claim by a classifier
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The paper
Abstract
Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources. We use cosmological simulations to predict the angular correlation functions of intensity fluctuations due to unresolved radio galaxies, cluster radio halos and relics and free-free emission from the interstellar and intergalactic medium at the frequencies and angular scales relevant for the proposed 21cm tomography. In accord with previous findings, the brightness temperature fluctuations due to foreground sources are much larger than those from the primary 21cm signal at all scales. In particular, diffuse cluster radio emission, which has been previously neglected, provides the most significant foreground contamination. However, we show that the contribution to the angular fluctuations at scales \theta > 1' is dominated by the spatial clustering of bright foreground sources. This excess can be removed if sources above flux levels S > 0.1 mJy are detected and removed. Hence, efficient source removal may be sufficient to allow the detection of angular fluctuations in the 21cm emission free of extragalactic foregrounds at \theta > 1 arcmin. In addition, the removal of sources above S=0.1 mJy also reduces the foreground fluctuations to roughly the same level as the 21cm signal at scales \theta < 1 arcmin. This should allow the substraction of the foreground components in frequency space, making it possible to observe in detail the topology and history of reionization.
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abstract compiled · 2026-09-23 · no language-model review
How the main claim is stated: hedged possibility 0.99
What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.34 · human participants 0.01 · controlled comparison 0.11 · randomized assignment 0.01 · states quantitative result 0.97 · compares with prior results 0.88 · mentions code or data availability 0.02
The abstract, sentence by sentence
This table labels the abstract only (arXiv listing abstract v2). The number is the probability the classifier gave the label.
| Sentence | Role | The authors' own work | States the main conclusion | Strength |
|---|---|---|---|---|
| Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. | background 1.00 | 0.06 | 0.02 | asserted 1.00 |
| We examine the observability of this signal and the impact of extragalactic foreground radio sources. | contribution 0.87 | 0.69 | 0.02 | unclear 0.51 |
| We use cosmological simulations to predict the angular correlation functions of intensity fluctuations due to unresolved radio galaxies, cluster radio halos and relics and free-free emission from the interstellar and intergalactic medium at the frequencies and angular scales relevant for the proposed 21cm tomography. | method 0.98 | 0.94 | 0.03 | asserted 0.96 |
| In accord with previous findings, the brightness temperature fluctuations due to foreground sources are much larger than those from the primary 21cm signal at all scales. | result 0.93 | 0.32 | 0.09 | asserted 0.99 |
| In particular, diffuse cluster radio emission, which has been previously neglected, provides the most significant foreground contamination. | result 0.97 | 0.69 | 0.14 | asserted 1.00 |
| However, we show that the contribution to the angular fluctuations at scales \theta > 1' is dominated by the spatial clustering of bright foreground sources. | result 0.99 | 0.89 | 0.18 | asserted 1.00 |
| This excess can be removed if sources above flux levels S > 0.1 mJy are detected and removed. | result 0.62 | 0.83 | 0.14 | asserted 0.51 |
| Hence, efficient source removal may be sufficient to allow the detection of angular fluctuations in the 21cm emission free of extragalactic foregrounds at \theta > 1 arcmin. | interpretation 0.85 | 0.85 | 0.66 | hedged possibility 0.99 |
| In addition, the removal of sources above S=0.1 mJy also reduces the foreground fluctuations to roughly the same level as the 21cm signal at scales \theta < 1 arcmin. | result 0.95 | 0.88 | 0.15 | asserted 0.53 |
| This should allow the substraction of the foreground components in frequency space, making it possible to observe in detail the topology and history of reionization. | interpretation 0.98 | 0.36 | 0.30 | hedged possibility 0.91 |
What kind of paper the classifier reports this is: simulation study 1.00 · evidence from simulation or computation 1.00
What was examined, and what was not
Sources read
- arXiv listing abstract v2
Not examined
- full text
- figures and tables
- references and citing sentences
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Levels run
- P abstract
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- S sections
- T body sentences
- C citations
- R cross-paper relations
How the labels were made
Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 7,668 input tokens.
Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. This record as JSON
Cited by 3 Pith papers
Reviewed papers on Pith that cite this one. The full citation record
- The CMBR fluctuations from HI perturbations prior to reionization astro-ph · Jan 2004
- A Method for 21cm Power Spectrum Estimation in the Presence of Foregrounds astro-ph.CO · Mar 2011
- Calibration requirements for Epoch of Reionization 21-cm signal observations - V. Bias and variance in the cylindrical power spectrum from uGMRT Band 3 observations of the ELAIS-N1 field astro-ph.CO · Oct 2026
How the literature uses it
5 arXiv papers cite this in 7 sentences
Papers citing it · 5 sentences without a confident label
Cites it as background 2 papers
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Early foreground cleaning proposals focused on using the angular structure of the foregrounds [ref] , while recent studies have suggested that a line-of-sight (LOS) spectral subtraction method may be the most promising approach [ref] .
A Method for 21cm Power Spectrum Estimation in the Presence of Foregrounds · Introduction · 0.98
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Broadly, the approaches for foreground removal involve using both the angular structure of foregrounds, and the spectral smoothness of synchrotron and free-free radiation (as compared to the highly structured cosmological signal) to distinguish them from the cosmological signal [ref] .
Detecting primordial gravitational waves with circular polarization of the redshifted 21 cm line: II. Forecasts · Foregrounds · 0.91
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