Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamic aspects of dark energy fluids   In this paper we have investigated the limits imposed by thermodynamics on a
dark energy fluid. We have obtained the heat capacities and the
compressibilities for a dark energy fluid. The thermal and mechanical
stabilities require these quantities to be positive. We have shown that dark
energy fluids must satisfy the stability conditions and that such requirement
put difficulties in the cosmic fluid models with negative constant EoS
parameters. We have also shown that the observational constraints imposed by SN
Ia, BAO and $H(z)$ data on a general dark energy fluid with a time-dependent
EoS parameter are in conflict with the constraints imposed by thermodynamics.
This result indicates that dark energy fluid models are unphysical.

10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas