Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: General relativistic corrections to $N$-body simulations and the
  Zel'dovich approximation   The initial conditions for Newtonian $N$-body simulations are usually
generated by applying the Zel'dovich approximation to the initial displacements
of the particles using an initial power spectrum of density fluctuations
generated by an Einstein-Boltzmann solver. We show that in most gauges the
initial displacements generated in this way receive a first-order relativistic
correction. We define a new gauge, the $N$-body gauge, in which this
relativistic correction vanishes and show that a conventional Newtonian
$N$-body simulation includes all first-order relativistic contributions (in the
absence of radiation) if we identify the coordinates in Newtonian simulations
with those in the relativistic $N$-body gauge.

28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg