Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Testing the magnetic field models of galaxies with the SKA   The future new-generation radio telescope SKA (Square Kilometre Array) and
its precursors will provide a rapidly growing number of polarized radio
sources. Hundred and thousands polarized background sources can be measured
towards nearby galaxies thus allowing their detailed magnetic field mapping by
means of Faraday rotation measures (RM). We aim to estimate the required
density of the background polarized sources detected with the SKA for reliable
recognition and reconstruction of the magnetic field structure in nearby spiral
galaxies. We construct a galaxy model which includes the ionized gas and
magnetic field patterns of different azimuthal symmetry (axisymmetric (ASS),
bisymmetric (BSS) and quadrisymmetric spiral (QSS), and superpositions) plus a
halo magnetic field. RM fluctuations with a Kolmogorov spectrum due to
turbulent fields and/or fluctuations in ionized gas density are superimposed.
Recognition of magnetic structures is possible from RM towards background
sources behind galaxies or a continuous RM map obtained from the diffuse
polarized emission from the galaxy itself. Under favourite conditions, about a
few dozens of polarized sources are sufficient for a reliable recognition.
Reconstruction of the field structure without precognition becomes possible for
a large number of background sources. A reliable reconstruction of the field
structure needs at least 20 RM values on a cut along the projected minor axis
which translates to approximately 1200 sources towards the galaxy. Radio
telescopes operating at low frequencies (LOFAR, ASKAP and the low-frequency SKA
array) may also be useful instruments for field recognition or reconstruction
with the help of RM, if background sources are still significantly polarized at
low frequencies (abriged).

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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: cond-mat
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin