Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Global Seismic Oscillations in Soft Gamma Repeaters   There is evidence that soft gamma repeaters (SGRs) are neutron stars which
experience frequent starquakes, possibly driven by an evolving, ultra-strong
magnetic field. The empirical power-law distribution of SGR burst energies,
analogous to the Gutenberg-Richter law for earthquakes, exhibits a turn-over at
high energies consistent with a global limit on the crust fracture size. With
such large starquakes occurring, the significant excitation of global seismic
oscillations (GSOs) seems likely. Moreover, GSOs may be self-exciting in a
stellar crust that is strained by many, randomly-oriented stresses. We explain
why low-order toroidal modes, which preserve the shape of the star and have
observable frequencies as low as ~ 30 Hz, may be especially susceptible to
excitation. We estimate the eigenfrequencies as a function of stellar mass and
radius, and their magnetic and rotational shiftings/splittings. We also
describes ways in which these modes might be detected and damped. There is
marginal evidence for 23 ms oscillations in the hard initial pulse of the 1979
March 5th event. This could be due to the $_3t_0$ mode in a neutron star with B
~ 10^{14} G or less; or it could be the fundamental toroidal mode if the field
in the deep crust of SGR 0526-66 is ~ 4 X 10^{15} G, in agreement with other
evidence. If confirmed, GSOs would give corroborating evidence for
crust-fracturing magnetic fields in SGRs: B >~ 10^{14} G.

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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: math
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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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: q-fin