Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic fluid spheres with particular application in cosmology and
  gravitational collapse   A spherically symmetric comoving fluid solution of Einstein's equations is
adapted for cosmological application by extending the geometry of standard FRW
cosmology using a generalised curvature term. The resulting model retains many
of the known cosmological properties including homogeneity of energy density,
its relationship with internal pressure including equations of state, although
in each case they have a generalised structure. It is shown that the adapted
model does not require the inclusion of the arbitrary cosmological constant and
the vacuum energy solution is discussed in its absence. The Hubble constant and
deceleration parameter are also shown to have a form which characterises the
modified geometry of the new model. These forms are calculated using current
observational data and show how the standard cosmological geometry can be
amended in a way which is consistent with an observed flat curvature and a
decelerating universe. Finally the solution is also considered in the context
of gravitational collapse where it is shown how fluids spheres obeying a
central equation of state can be matched to empty spacetime.

26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int