Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The 21 centimeter emission from the reionization epoch: extended and
  point source foregrounds   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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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: cs
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The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph