Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A study of positive energy condition in Bianchi V spacetimes via Noether
  symmetries   In this paper we use Noether symmetries of the geodesic Lagrangian in Bianchi
V spacetimes to study various cosmological solutions of Einstein's field
equations. Our first result is the identification of the subalgebras of Noether
symmetries of the equations of motions in such spacetimes with dimension 4, 5,
6, 7, 9 or 10 of the maximal algebra of Lie point symmetries of dimension 13.
Secondly we give physical interpretation of new cosmological solutions which
satisfy positive energy condition and yield critical bounds on the expansion
coefficient $\alpha$, in which the underlying non-flat spacetimes carry
interesting physical properties. Specifically the energy density behaves in one
of the following ways. (i) It is positive and constant for all time. (ii) It
varies with time and attains a global maximum after some time and then
asymptotically converges to zero. (iii) It increases for all time and attains a
maximum value at the asymptotic limit $t\rightarrow \infty$. In particular a
non-flat spacetime is obtained that mimics the expansion in a flat FRW universe
dominated by vacuum energy such that the expansion factor has the same form in
both. However, the energy density is dynamical in the former.

21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin