Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing the warm Inter-Galactic Medium through absorption against Gamma
  Ray Bursts X-ray afterglows   Gamma Ray Burst (GRB) afterglows close to their peak intensity are among the
brightest X-ray sources in the sky. Despite their fast power-law like decay,
when fluxes are integrated from minutes up to hours after the GRB event, the
corresponding number counts (logN-logF relation) far exceeds that of any other
high redshift (z>0.5) source, the flux of which is integrated over the same
time interval. We discuss how to use X-ray afterglows of GRBs as distant
beacons to probe the warm (10^5 K<T<10^7 K) intergalactic matter in filaments
and outskirts of clusters of galaxies by means of absorption features, the
``X-ray forest''. According to current cosmological scenarios this matter may
comprise 30-40% of the baryons in the Universe at z<1. Present-generation X-ray
spectrometers such as those on Chandra and XMM-Newton can detect it along most
GRBs' lines of sight, provided afterglows are observed fast enough (within
hours) after the burst. A dedicated medium-sized X-ray telescope (effective
area <=0.1 m^2) with pointing capabilities similar to that of Swift (minutes)
and high spectral resolution (E/DeltaE>=300) would be very well suited to
exploit the new diagnostic and study the physical conditions in the Universe at
the critical moment when structure is being formed.

25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
34
The categories of this paper are: chem-ph