Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: MHD simulations of oscillating cusp-filling tori around neutron stars --
  missing upper kHz QPO   We performed axisymmetric, grid-based, ideal magnetohydrodynamic (MHD)
simulations of oscillating cusp-filling tori orbiting a non-rotating neutron
star. A pseudo-Newtonian potential was used to construct the constant angular
momentum tori in equilibrium. The inner edge of the torus is terminated by a
"cusp" in the effective potential. The initial motion of the model tori was
perturbed with uniform sub-sonic vertical and diagonal velocity fields. As the
configuration evolved in time, we measured the mass accretion rate on the
neutron star surface and obtained the power spectrum. The prominent mode of
oscillation in the cusp torus is the radial epicyclic mode. It would appear
that vertical oscillations are suppressed by the presence of the cusp. From our
analysis it follows that the mass accretion rate carries a modulation imprint
of the oscillating torus, and hence so does the boundary layer luminosity.

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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex