X-ray emissions from two-temperature accretion flows within a dipole magnetic funnel

作者：Saxton Curtis J^*; Wu Kinwah; C****le Joao B G; Cropper Mark; Ramsay Gavin

来源：Monthly Notices of the Royal Astronomical Society, 2007, 379(2): 779-790.

DOI：10.1111/j.1365-2966.2007.11958.x

• accretion, accretion discs
• hydrodynamics
• shock waves
• binaries : close
• white dwarfs
• X-rays : binaries

We investigate the hydrodynamics of accretion channelled by a dipolar magnetic field (funnel flows). We consider situations in which the electrons and ions in the flow cannot maintain thermal equilibrium [two-temperature (2T) effects] due to strong radiative loss, and determine the effects on the keV X-ray properties of the systems. We apply this model to investigate the accretion shocks of white dwarfs in magnetic cataclysmic variables (mCVs). We have found that the incorporation of 2T effects could harden the keV X-rays. Also, the dipolar model yields harder X-ray spectra than the standard planar model if white dwarf is sufficiently massive (greater than or similar to 1 M(circle dot)). When fitting observed keV X-ray spectra of mCVs, the inclusion of 2T hydrodynamics and a dipolar accretion geometry lowers estimates for white dwarf masses when compared with masses inferred from models excluding these effects. We find mass reductions less than or similar to 9 per cent in the most massive cases.

• 出版日期2007-8-1
• 单位清华大学