Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact Relativistic Gravitational Field of a Stationary Counterrotating
  Dust Disk   Disks of collisionless particles are important models for certain galaxies
and accretion disks in astrophysics. We present here a solution to the
stationary axisymmetric Einstein equations which represents an infinitesimally
thin dust disk consisting of two streams of particles circulating with constant
angular velocity in opposite directions. These streams have the same density
distribution but their relative density may vary continuously. In the limit of
only one component of dust, we get the solution for the rigidly rotating dust
disk previously given by Neugebauer and Meinel, in the limit of identical
densities, the static disk of Morgan and Morgan is obtained. We discuss the
Newtonian and the ultrarelativistic limit, the occurrence of ergospheres, and
the regularity of the solution.

2
The categories of this paper are: math
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph