Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intensity and Polarization Characteristics of Extended Neutron Star
  Surface Regions   The surfaces of neutron stars are sources of strongly polarized soft X rays
due to the presence of strong magnetic fields. Radiative transfer mediated by
electron scattering and free-free absorption is central to defining local
surface anisotropy and polarization signatures. Scattering transport is
strongly influenced by the complicated interplay between linear and circular
polarizations. This complexity has been captured in a sophisticated magnetic
Thomson scattering simulation we recently developed to model the outer layers
of fully-ionized atmospheres in such compact objects, heretofore focusing on
case studies of localized surface regions. Yet, the interpretation of observed
intensity pulse profiles and their efficacy in constraining key neutron star
geometry parameters is critically dependent upon adding up emission from
extended surface regions. In this paper, intensity, anisotropy and polarization
characteristics from such extended atmospheres, spanning considerable ranges of
magnetic colatitudes, are determined using our transport simulation. These
constitute a convolution of varied properties of Stokes parameter information
at disparate surface locales with different magnetic field strengths and
directions relative to the local zenith. Our analysis includes full general
relativistic propagation of light from the surface to an observer at infinity.
The array of pulse profiles for intensity and polarization presented highlights
how powerful probes of stellar geometry are possible. Significant
phase-resolved polarization degrees in the range of 10-60% are realized when
summing over a variety of surface field directions. These results provide an
important background for observations to be acquired by NASA's new IXPE X-ray
polarimetry mission.

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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: econ
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The categories of this paper are: physics
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org