Intensity and Polarization Characteristics of Extended Neutron Star Surface Regions

dc.citation.articleNumber82en_US
dc.citation.journalTitleThe Astrophysical Journalen_US
dc.citation.volumeNumber928en_US
dc.contributor.authorHu, Kunen_US
dc.contributor.authorBaring, Matthew G.en_US
dc.contributor.authorBarchas, Joseph A.en_US
dc.contributor.authorYounes, Georgeen_US
dc.date.accessioned2022-04-28T14:28:39Zen_US
dc.date.available2022-04-28T14:28:39Zen_US
dc.date.issued2022en_US
dc.description.abstractThe 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 Imaging X-ray Polarimetry Explorer X-ray polarimetry mission.en_US
dc.identifier.citationHu, Kun, Baring, Matthew G., Barchas, Joseph A., et al.. "Intensity and Polarization Characteristics of Extended Neutron Star Surface Regions." <i>The Astrophysical Journal,</i> 928, (2022) IOP Publishing: https://doi.org/10.3847/1538-4357/ac4ae8.en_US
dc.identifier.digitalHu_2022_ApJ_928_82en_US
dc.identifier.doihttps://doi.org/10.3847/1538-4357/ac4ae8en_US
dc.identifier.urihttps://hdl.handle.net/1911/112166en_US
dc.language.isoengen_US
dc.publisherIOP Publishingen_US
dc.rightsOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.en_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en_US
dc.titleIntensity and Polarization Characteristics of Extended Neutron Star Surface Regionsen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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