Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The dark-matter world: Are there dark-matter galaxies?   We attempt to answer whether neutrinos and antineutrinos, such as those in
the cosmic neutrino background, would clusterize among themselves or even with
other dark-matter particles, under certain time span, say 1 Gyr. With neutrino
masses in place, the similarity with the ordinary matter increases and so is
our confidence for neutrino clustering if time is long enough. In particular,
the clusterings could happen with some seeds (cf. see the text for definition),
the chance in the dark-matter world to form dark-matter galaxies increases. If
the dark-matter galaxies would exist in a time span of 1 Gyr, then they might
even dictate the formation of the ordinary galaxies (i.e. the dark-matter
galaxies get formed first); thus, the implications for the structure of our
Universe would be tremendous.

12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess