Spectral Energy Distribution of Ultraluminous X-ray Sources from X-ray to the Optical Range

We model spectral energy distributions (SEDs) of ultraluminous X-ray sources (ULXs) using Shakura and Sunyaev's approach to a supercritical accretion disk. We consider a funnel in the supercritical accretion disk and wind arising in the funnel. The wind is illuminated by funnel radiation and it reprocesses the radiation to the UV and optical ranges. We take into account Comptonization of a hot corona which covers inner parts of the supercritical disk. We apply the model to a typical ultraluminous X-ray source Holmberg II X-1.