Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma-Ray Bursts versus Quasars: Lyman-alpha Signatures of Reionization
  versus Cosmological Infall   Lyman-alpha absorption is a prominent cosmological tool for probing both
galactic halos and the intergalactic medium at high redshift. We consider a
variety of sources that can be used as the Lyman-alpha emitters for this
purpose. Among these sources, we argue that quasars are the best probes of the
evolution of massive halos, while gamma-ray bursts represent the cleanest
sources for studying the reionization of the intergalactic medium.

37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin