Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Galactic magnetic field and its lensing of ultrahigh energy and
  Galactic cosmic rays   It has long been recognized that magnetic fields play an important role in
many astrophysical environments, yet the strength and structure of magnetic
fields beyond our solar system have been at best only qualitatively
constrained. The Galactic magnetic field in particular is crucial for modeling
the transport of Galactic CRs, for calculating the background to dark matter
and CMB-cosmology studies, and for determining the sources of UHECRs. This
report gives a brief overview of recent major advances in our understanding of
the Galactic magnetic field (GMF) and its lensing of Galactic and ultrahigh
energy cosmic rays.

4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th