Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resonant Compton Upscattering in Anomalous X-ray Pulsars   A significant new development in the study of Anomalous X-ray Pulsars (AXPs)
has been the recent discovery by INTEGRAL and RXTE of flat, hard X-ray
components in three AXPs. These non-thermal spectral components differ
dramatically from the steeper quasi-power-law tails seen in the classic X-ray
band in these sources. A prime candidate mechanism for generating this new
component is resonant, magnetic Compton upscattering. This process is very
efficient in the strong magnetic fields present in AXPs. Here an introductory
exploration of an inner magnetospheric model for upscattering of surface
thermal X-rays in AXPs is offered, preparing the way for an investigation of
whether such resonant upscattering can explain the 20-150 keV spectra seen by
INTEGRAL. Characteristically flat emission spectra produced by non-thermal
electrons injected in the emission region are computed using collision
integrals. A relativistic QED scattering cross section is employed so that
Klein-Nishina reductions are influential in determining the photon spectra and
fluxes. Spectral results depend strongly on the magnetospheric locale of the
scattering and the observer's orientation, which couple directly to the angular
distributions of photons sampled.

8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
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The categories of this paper are: adap-org
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph