Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pulsar bow shocks as probes of warm neutral gas   Pulsars have mean space velocities >~500 km/s. The consequent ram pressure
results in tight confinement of the star's energetic wind, driving a bow shock
into the surrounding medium. Pulsar bow shocks have long been regarded as a
curiosity, but new optical and X-ray observations are both rapidly expanding
the sample of such sources, and are offering new ways to probe the interaction
between pulsars and their environments. Here we discuss some of these new
results, and explain how these data can be used to probe the density and
structure of neutral gas in the interstellar medium.

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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an