http://arxiv.org/abs/1610.04292
We develop a general method for the self consistent calculation of the hydrodynamics of an astrophysical object irradiated by a radiation field with an arbitrary strength and spectral energy distribution (SED). Using the XSTAR photoionization code we calculate heating and cooling rates as a function of gas photoionization parameter and temperature for several examples of SEDs: bremsstrahlung, blackbody, hard and soft state XRBs, Type 1 and Type 2 AGN. We numerically investigate the properties of a spherical object heated by a uniform radiation field using the MHD code Athena++. We find that in all cases explored a wind settles into a transonic, steady state. The wind evolves along the radiative heating equilibrium curve until adiabatic cooling effects become important and the flow departs from radiative equilibrium. The efficiency with which the radiation field transfers energy to the wind is dependent on the SED of the external source, particularly the relative flux of soft X-rays. If the flow is heated very rapidly, for example as in a thermally unstable regime, the corresponding column density of gas is low. These results suggest that detailed photoionization calculations are essential not only to predict spectra but also to properly capture the flow dynamics.
S. Dyda, R. Dannen, T. Waters, et. al.
Mon, 17 Oct 16
9/53
Comments: 12 pages, 6 figures
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