Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The local Galactic magnetic field in the direction of Geminga   The Milagro hot spot A, close to the Galactic anticenter direction, has been
tentatively attributed to cosmic rays from a local reservoir (at a distance
~100 pc), freely streaming along diverging and smooth magnetic field lines.
This is at variance with the geometry of the ~kpc scale Galactic magnetic
field, which is known to be aligned with the spiral arms. We investigate the
information available on the geometry of the magnetic field on the scales (~100
pc) of relevance here. The magnetic field immediately upstream of the
heliosphere has been investigated by previous authors by modeling the
interaction of this field with the solar wind. At larger distances, we use the
dispersion measure and the rotation measure of nearby pulsars (especially
towards the third Galactic quadrant). Additional information about the local
field towards the North Polar Spur is taken from previous studies of the
diffuse radio emission and the polarization of starlight. The asymmetry of the
heliosphere with respect to the incoming interstellar medium implies a magnetic
field almost orthogonal to the local spiral arm, in the general direction of
hot spot A, but more to the south. This is in good agreement with the nearby
pulsar data on the one side, and the North Polar Spur data on the other. The
local magnetic field on scales of ~100 parsecs around the Sun seems to be
oriented so as to provide a direct connection between the Solar system and a
possible site of the Geminga supernova; the residual angular difference and the
shape and orientation of the Milagro hot spot can be attributed to the field
trailing in the wake of the heliosphere.

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The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: eess
4
The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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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: q-bio
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The categories of this paper are: stat
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The categories of this paper are: chem-ph