Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmic Magnetism in Centimeter and Meter Wavelength Radio Astronomy   Magnetic field is ubiquitous in the Universe and it plays essential roles in
various astrophysical phenomena, yet its real origin and evolution are poorly
known. This article reviews current understanding of magnetic fields in the
interstellar medium, the Milky Way Galaxy, external galaxies, active galactic
nuclei, clusters of galaxies, and the cosmic web. Particularly, the review
concentrates on the achievements that have been provided by centimeter and
meter wavelength radio observations. The article also introduces various
methods to analyze linear polarization data, including synchrotron radiation,
Faraday rotation, depolarization, and Faraday tomography.

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The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin