Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Black Hole solutions in a cosmological spacetime background   We propose and analyze a new metric that has two conformal factors a(t) and
b(t) that combine the expansion of the universe and its effects on the spatial
and temporal part of the Schwarzschild metric in isotropic coordinates. We
present the solutions, their descriptions and we comment on their shortcomings.
In the spatially flat case of an expanding universe, we derive from the
proposed metric the special solutions of the field equations for the dust
approximation and the McVittie metric. We show that the presence of a black
hole does not modify the a(t) proportional to t^{2/3} law for dust and
H=constant for dark energy.

31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol