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Science 332, 6028 (2011) 438-439
Polarized Gamma-Ray Emission from the Galactic Black Hole Cygnus X-1
P. Laurent1, 2, J. Rodriguez2, 3, J. Wilms4, M. Cadolle Bel5, K. Pottschmidt6, V. Grinberg4
INTEGRAL Collaboration(s)

Because of their inherently high flux allowing the detection of clear signals, black hole x-ray binaries are interesting candidates for polarization studies, even if no polarization signals have been observed from them before. Such measurements would provide further detailed insight into these sources' emission mechanisms. We measured the polarization of the gamma-ray emission from the black hole binary system Cygnus X-1 with the International Gamma-Ray Astrophysics Laboratory Imager on Board the Integral Satellite (INTEGRAL/IBIS) telescope. Spectral modeling of the data reveals two emission mechanisms: The 250- to 400-keV (kilo-electron volt) data are consistent with emission dominated by Compton scattering on thermal electrons and are weakly polarized. The second spectral component seen in the 400-keV to 2-MeV band is by contrast strongly polarized, revealing that the MeV emission is probably related to the jet first detected in the radio band.
1 :  APC - UMR 7164 - AstroParticule et Cosmologie
2 :  IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers (ex DAPNIA)
3 :  AIM - UMR 7158 - Astrophysique Interactions Multi-échelles
4 :  ECAP - Erlangen Centre for Astroparticle Physics
5 :  ESAC - European Space Astronomy Centre
6 :  NASA Goddard Space Flight Center - NASA Goddard Space Flight Center
Planète et Univers/Astrophysique/Phénomènes cosmiques de haute energie

Physique/Astrophysique/Phénomènes cosmiques de haute energie
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