Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galactic Spiral Arms: Structure and Dynamics Given by an Equation of
  Motion   Using an equation of motion for a self-gravitating filament, we show how
galactic spiral arms might be created and sustained. We find that the
combination of differential rotation of the galactic disk and the self-gravity
of the arm (as given by the equation) leads to a rotating spiral structure.
Moreover, using this analysis, we then find a second differential equation that
explicitly relates this spiral structure to the rotation curve of the galaxy --
it connects several factors, including spiral shape and pattern speed. We also
describe a simple many-body numerical experiment that supports our approach.
The findings are with consistent with observational evidence concerning arm
structure and rotation curves, including leading arm structures.

9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an