Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Str\"omgren sphere, the environment and the reionization in the
  local universe of the highest redshift QSOs   In this paper we investigate the environment and reionization process around
the highest redshift QSOs having Gunn-Peterson troughs (z>6.1). Starting with
the cosmic density perturbation and structure formation theory and the fact
that the highest redshift QSOs are located in rare overdense regions, we show
that the halo formation, gas distribution, and star formation around QSOs are
biased from those of the cosmic average. We argue that a significant fraction
of hydrogen in the Str\"omgren sphere around QSOs is ionized by photons from
stars and that only about several percent to at most 10%--20% of the total
hydrogen is left (e.g., in minihalos, halos, or high-density subregions) to be
ionized by QSO photons. The cosmic average neutral hydrogen fraction at
z~6.2-6.4 should also be smaller than the upper limit of 10%--20% and may be
only a few percent. We analyze the clumping property of the hydrogen ionized by
QSOs and study the evolution of the Str\"omgren sphere. We find that the
expected Str\"omgren radii from our models are consistent with observations if
the lifetime of the highest redshift QSOs is about or longer than a few times
10^7 yr (as is the lifetime of the main population of QSOs; with comoving
number density peaked at z~2-3). With such a QSO lifetime, the ages of most of
the observed QSOs are long enough that the QSO photon emission is balanced by
the recombination of the hydrogen ionized by QSO photons in their Str\"omgren
spheres, and the expected Str\"omgren radii from the balance are independent of
the detailed values of the QSO ages. (abridged)

28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc