Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Statistical characteristics of Large Scale Structure   We investigate the mass functions of different elements of the Large Scale
Structure -- walls, pancakes, filaments and clouds -- and the impact of
transverse motions -- expansion and/or compression -- on their statistical
characteristics. Using the Zel'dovich theory of gravitational instability we
show that the mass functions of all structure elements are approximately the
same and the mass of all elements is found to be concentrated near the
corresponding mean mass. At high redshifts, both the mass function and the mean
mass of formed elements depend upon the small scale part of the initial power
spectrum and, in particular, upon the mass of dominant fraction of dark matter
(DM) particles. These results generalize the Press-Schechter approach and are
used to obtain independent estimates of probable redshifts of the reionization
and reheating periods of the Universe. We show that the transverse motions do
not significantly change the redshift evolution of the observed mass function
and the mean linear number density of low mass pancakes related to absorption
lines in the spectra of the farthest quasars. We apply this approach to the
observed Lyman-$\alpha$ clouds and obtain direct estimates of the variance of
initial density perturbations and the shape of initial power spectrum on small
scale. In turn, these estimates restrict the mass of dominant fraction of DM
particles.

10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math