Radiation Hydrodynamic simulations of Coronae and Disk winds in X-ray Binaries
Abstract
X-ray spectra of several Low Mass X-ray binaries show evidence of disk-winds in the high/soft state. A promising driving mechanism for these outflows is the thermal expansion of X-ray heated material in the outer disk atmosphere. First, we demonstrate through hydrodynamical simulations that the properties of thermally-driven winds depend critically on the shape of the thermal equilibrium curve, which determines the thermal stability of the irradiated material. For a given SED, the thermal equilibrium curve depends on the balance between the heating and cooling mechanisms at work. Then, we use the photoionization code Cloudy to generate heating and cooling rates based on current atomic data, which we use in a 2.5D hydrodynamic model to simulate thermal winds in a typical black-hole X-ray binary. The resulting flow, calculated in the optically thin limit, has a significant mass-loss rate, likely at the level where the wind could affect the inner disk and cause state change. Finally, we discuss a more complete simulation of a disk wind in a low mass X-ray binary, dropping the assumption that the wind is everywhere optically thin, using our Monte-Carlo radiative transfer code to calculate the radiation field within the wind and to update the heating rates.
- Publication:
-
The X-ray Universe 2017
- Pub Date:
- October 2017
- Bibcode:
- 2017xru..conf..100H