Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Escaping the Big Rip?   We discuss dark energy models which might describe effectively the actual
acceleration of the universe. More precisely, for a 4-dimensional
Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) universe we consider two
situations: First of them, we model dark energy by phantom energy described by
a perfect fluid satisfying the equation of state $P=(\beta-1)\rho$ (with
$\beta<0$ and constant). In this case the universe reaches a ``Big Rip''
independently of the spatial geometry of the FLRW universe. In the second
situation, the dark energy is described by a phantom (generalized) Chaplygin
gas which violates the dominant energy condition. Contrary to the previous
case, for this material content a FLRW universe would never reach a ``big rip''
singularity (indeed, the geometry is asymptotically de Sitter). We also show
how this dark energy model can be described in terms of scalar fields,
corresponding to a minimally coupled scalar field, a Born-Infeld scalar field
and a generalized Born-Infeld scalar field. Finally, we introduce a
phenomenologically viable model where dark energy is described by a phantom
generalized Chaplygin gas.

36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs