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X-ray Modeling of η Carinae and WR140 from SPH Simulations

The colliding wind binary (CWB) systems η Carinae and WR140 provide unique laboratories for X-ray astrophysics. Their wind-wind collisions produce hard X-rays that have been monitored extensively by several X-ray telescopes, including RXTE. To interpret these X-ray light curves and spectra, we apply 3D hydrodynamic simulations of the wind-wind collision using smoothed particle hydrodynamics (SPH), with the recent improvements of radiative cooling and the acceleration of the stellar winds according to a β law. For both systems, the 2-10 keV RXTE light curves are well-reproduced in absolute units for most phases, but the light curve dips associated with the periastron passages are not well matched. In WR140, the dip is too weak, and in η Carinae, the large difference in wind speeds of the two stars leads to a hot, post-periastron bubble that produces excess emission toward the end of the X-ray minimum.