Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On kHz oscillations and characteristic frequencies of accreting
  magnetospheres   When an accreting star is close to rotational equilibrium between the dipole
component of the stellar magnetic field and the accretion disk, the star's
rotation rate is roughly of the order of the Keplerean rotation rate at the
inner boundary of the disk, estimated as the conventional Alfven radius. A
range of frequencies higher than this equilibrium rotation frequency can
naturally arise if the accretion flow is channeled by higher multipoles of the
star's magnetic field. The higher multipole components of the magnetic field
will balance the material stresses of the accretion flow at radii closer to the
star. The Kepler frequencies associated with these generalized Alfven radii
increase with the order of the multipole. Other frequency bands, like the
epicyclic frequencies associated with the accretion flow, may in turn be higher
than the Kepler frequencies. We present expressions for the spectrum of higher
frequencies arising due to these effects. Kilohertz quasi-periodic oscillation
frequencies that are much higher than the rotation rate of the neutron star, as
observed from the recently discovered 11 Hz (P = 90 ms) X-ray pulsar IGR
J17480-2446 in the globular cluster Terzan 5, may be due to modulation of the
accretion rate by the excitation of these modes in the accretion flow. The very
high QPO frequencies observed from the soft gamma repeaters SGR 1806-20 (P =
5.2 s) and SGR 1900+14 (P = 7.5 s) may also correspond to these characteristic
frequencies if SGRs accrete from fallback disks around them.

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The categories of this paper are: math-ph
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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: nucl-ex
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The categories of this paper are: physics
0
The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: mtrl-th