Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A whirling plane of satellite galaxies around Centaurus A challenges
  cold dark matter cosmology   The Milky Way and Andromeda galaxy are each surrounded by a thin plane of
satellite galaxies that may be corotating. Cosmological simulations predict
that most satellite galaxy systems are close to isotropic with random motions,
so those two well-studied systems are often interpreted as rare statistical
outliers. We test this assumption using the kinematics of satellite galaxies
around the Centaurus A galaxy. Our statistical analysis reveals evidence for
corotation in a narrow plane: of the 16 Centaurus A's satellites with kinematic
data, 14 follow a coherent velocity pattern aligned with the long axis of their
spatial distribution. In standard cosmology simulations, < 0.5% of Centaurus
A-like systems show such behavior. Corotating satellite systems may be common
in the Universe, challenging small-scale structure formation in the prevailing
cosmological paradigm.

13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
2
The categories of this paper are: math
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con