Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Damping and Excitation of Galactic Warps by Dynamical Friction   We investigate the dynamical interaction of galactic warps with the
surrounding dark matter halo, using analytic perturbation theory. A precessing
warp induces a density wake in the collisionless dark matter, which acts back
on the original warp, transferring energy and angular momentum between the warp
and halo (dynamical friction). In most cases dynamical friction damps the warp,
but in unusual circumstances (such as a halo that rotates in the same direction
as the precession of the warp, or a warp in the equatorial plane of an
axisymmetric prolate halo) friction can excite a warp. The damping/excitation
time is usually short compared to the Hubble time for realistic systems. Thus
most warps cannot be primordial; they must be maintained by some ongoing
excitation mechanism.

20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin