Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detection of a Double Relic in the Torpedo Cluster: SPT-CL J0245-5302   The Torpedo cluster, SPT-CL J0245-5302 (S0295) is a massive, merging cluster
at a redshift of z = 0.300, which exhibits a strikingly similar morphology to
the Bullet cluster 1E 0657-55.8 (z = 0.296), including a classic bow shock in
the cluster's intra-cluster medium revealed by Chandra X-ray observations. We
present Australia Telescope Compact Array data centred at 2.1 GHz and Murchison
Widefield Array data at frequencies between 72 MHz and 231 MHz which we use to
study the properties of the cluster. We characterise a number of discrete and
diffuse radio sources in the cluster, including the detection of two previously
unknown radio relics on the cluster periphery. The average spectral index of
the diffuse emission between 70 MHz and 3.1 GHz is
$\alpha=-1.63_{-0.10}^{+0.10}$ and a radio-derived Mach number for the shock in
the west of the cluster is calculated as M = 2.04. The Torpedo cluster is thus
as a double relic system at moderate redshift.

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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: physics
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn