Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Powering of H$\alpha$ filaments by cosmic rays   Cluster cool cores possess networks of line-emitting filaments. These
filaments are thought to originate via uplift of cold gas from cluster centers
by buoyant active galactic nuclei (AGN) bubbles, or via local thermal
instability in the hot intracluster medium (ICM). Therefore, the filaments are
either the signatures of AGN feedback or feeding of supermassive black holes.
Despite being characterized by very short cooling times, the filaments are
significant H$\alpha$ emitters, which suggests that some process continuously
powers these structures. Many cool cores host diffuse radio mini halos and AGN
injecting radio plasma, suggesting that cosmic rays (CRs) and magnetic fields
are present in the ICM. We argue that the excitation of Alfv\'en waves by CR
streaming, and the replenishment of CR energy via accretion onto the filaments
of high plasma-$\beta$ ICM characterized by low CR pressure support, can
provide the adequate amount of heating to power and sustain the emission from
these filaments. This mechanism does not require the CRs to penetrate the
filaments even if the filaments are magnetically isolated from the ambient ICM
and it may operate irrespectively of whether the filaments are dredged up from
the center or form in situ in the ICM. This picture is qualitatively consistent
with non-thermal line ratios seen in the cold filaments. Future X-ray
observations of the iron line complex with XARM, Lynx, or Athena could help to
test this model by providing constraints on the amount of CRs in the hot plasma
that is cooling and accreting onto the filaments.

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The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci