Apparent photosphere, thermalization surface and spectrum of black hole winds: Frequency-dependent case

We examine the apparent photosphere, thermalization surface and expected spectrum of a black hole wind, which is an optically thick, spherically symmetric outflow blown off from the very center of a black hole, taking into account the frequency dependence of opacities. In the case of the optically thick spherical wind, the apparent photosphere is generally aspherical, since the wind density gradua...