Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: How "free" are free neutrons in neutron-star crusts and what does it
  imply for pulsar glitches ?   The neutron superfluid permeating the inner crust of mature neutron stars is
expected to play a key role in various astrophysical phenomena like pulsar
glitches. Despite the absence of viscous drag, the neutron superfluid can still
be coupled to the solid crust due to non-dissipative entrainment effects.
Entrainment challenges the interpretation of pulsar glitches and suggests that
a revision of the interpretation of other observed neutron-star phenomena might
be necessary.

2
The categories of this paper are: math
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph