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Paper: X-Ray beaming due to resonance scattering in the accretion column of polars
Volume: 261, The Physics of Cataclysmic Variables and Related Objects
Page: 175
Authors: Terada, Y.; Makishima, K.; Ishida, M.; Fujimoto, R.; Matsuzaki, K.; Kaneda, H.
Abstract: Extremely intense ionized Fe emission lines, with the equivalent width reaching about 4000 eV, was discovered in the X-ray observation with ASCA from a few Galactic compact objects, which are thought to be polar systems. The puzzlingly strong Fe-K lines were attributed to a new scenario of line-photon collimation in the accretion column of the white dwarf, due to resonance scattering of line photons. The collimation is caused by the column shape and the vertical velocity gradient, which reduces the resonant trapping of resonant photons along the magnetic field lines. The proposed mechanism was confirmed via Monte-Carlo simulation, as well as the examination of the ASCA observation of V834 Centauri for a rotational modulation of the equivalent width of the Fe-K emission line.
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