IAU Colloquium N° 102 on UV and X-ray Spectroscopy of Astrophysical and Laboratory Plasmas
J. Phys. Colloques 49 (1988) C1-47-C1-50
DOI: 10.1051/jphyscol:1988107
IRON K-LINE EMISSION FROM X-RAY BINARIES
K. MASAI1, S. HAYAKAWA2 et F. NAGASE21 Institute of Plasma Physics, Nagoya 464, Japan
2 Department of Astrophysics, Nagoya University, Nagoya 464, Japan
Abstract
Emission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Tx of continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ~ 100 eV formed above the accretion disk. This mechanism is attained for Tx ≤ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx > 10 keV is likely due to fluorescence outside the He II ionization front.