Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for Asymmetry in the Velocity Distribution of the Interstellar
  Neutral Helium Flow Observed by IBEX and Ulysses   We use observations from the Interstellar Boundary Explorer (IBEX) and
Ulysses to explore the possibility that the interstellar neutral helium flowing
through the inner solar system possesses an intrinsic non-Maxwellian velocity
distribution. In fitting the IBEX and Ulysses data, we experiment with both a
kappa distribution and a bi-Maxwellian, instead of the usual Maxwellian
assumption. The kappa distribution does not improve the quality of fit to
either the IBEX or Ulysses data, and we find lower limits to the kappa
parameter of kappa>12.1 and kappa>6.0 from the IBEX and Ulysses analyses,
respectively. In contrast, we do find evidence that a bi-Maxwellian improves
fit quality. For IBEX, there is a clear preferred bi-Maxwellian solution with
T_perp/T_par=0.62+/-0.11 oriented about an axis direction with ecliptic
coordinates (lambda_axis,b_axis)=(57.2+/-8.9 deg,-1.6+/-5.9 deg). The Ulysses
data provide support for this result, albeit with lower statistical
significance. The axis direction is close to the ISM flow direction, in a
heliocentric rest frame, and is therefore unlikely to be indicative of velocity
distribution asymmetries intrinsic to the ISM. It is far more likely that these
results indicate the presence of asymmetries induced by interactions in the
outer heliosphere.

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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: cond-mat
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: stat
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The categories of this paper are: q-bio