Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR
  B0355+54   We report on Chandra X-ray Observatory (CXO) observations of the pulsar wind
nebula (PWN) associated with PSR B0355+54 (eight observations with a 395 ks
total exposure, performed over an 8 month period). We investigated the spatial
and spectral properties of the emission coincident with the pulsar, compact
nebula (CN), and extended tail. We find that the CN morphology can be
interpreted in a way that suggests a small angle between the pulsar spin axis
and our line-of-sight, as inferred from the radio data. On larger scales,
emission from the 7' (2 pc) tail is clearly seen. We also found hints of two
faint extensions nearly orthogonal to the direction of the pulsar's proper
motion. The spectrum extracted at the pulsar position can be described with an
absorbed power-law + blackbody model. The nonthermal component can be
attributed to magnetospheric emission, while the thermal component can be
attributed to emission from either a hot spot (e.g., a polar cap) or the entire
neutron star surface. Surprisingly, the spectrum of the tail shows only a
slight hint of cooling with increasing distance from the pulsar. This implies
either a low magnetic field with fast flow speed, or particle re-acceleration
within the tail. We estimate physical properties of the PWN and compare the
morphologies of the CN and the extended tail with those of other bow shock PWNe
observed with long CXO exposures.

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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: chem-ph
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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: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: hep-ph