Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Natural Explanation for Magnetars   We explore the possibility that a magnetar may owe its strong magnetic field
to a magnetized core which, as indicated by certain equations of state, may
form due to phase transitions at high density mediated by strong interaction
within a sufficiently massive neutron star. We argue that the field derived
from such a core could explain several inferred evolutionary behaviors of
magnetars.

37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys