Blue–shifted absorption lines from highly ionised iron are seen in some high inclination X-ray binary systems , indicating the presence of an equatorial disc wind .
This launch mechanism is under debate , but thermal driving should be ubiquitous .
X-ray irradiation from the central source heats disc surface , forming a wind from the outer disc where the local escape velocity is lower than the sound speed .
The mass loss rate from each part of the disc is determined by the luminosity and spectral shape of the central source .
We use these together with an assumed density and velocity structure of the wind to predict the column density and ionisation state , then combine this with a Monte-Carlo radiation transfer to predict the detailed shape of the absorption ( and emission ) line profiles .
We test this on the persistent wind seen in the bright neutron star binary GX 13+1 , with luminosity L / L _ { \mathrm { Edd } } \sim 0.5 .
We approximately include the effect of radiation pressure because of high luminosity , and compute line features .
We compare these to the highest resolution data , the Chandra third order grating spectra , which we show here for the first time .
This is the first physical model for the wind in this system , and it succeeds in reproducing many of the features seen in the data , showing that the wind in GX13+1 is most likely a thermal-radiation driven wind .
This approach , combined with better streamline structures derived from full radiation hydrodynamic simulations , will allow future calorimeter data to explore the detail wind structure .