High-redshift radio-quiet quasars: Exploring the parameter space of accretion models. II. Patchy corona model

We modeled the spectral energy distribution of high-redshift radio-quiet quasars (high-z RQQs). We computed spectra in a patchy corona geometry in which an accretion disk extends to the last stable orbit and the Comptonizing active regions (hot clouds) are distributed above the disk. We explored the model parameter space to find theoretical parameters that give spectra with an optical/UV luminosity, X-ray loudness, and X-ray photon index compatible with those of high-z RQQs observed with Chandra. We found that a range of solutions is possible, from high-kT(e) low-tau to low-kT(e) high-tau models. The solutions require a low level of energy dissipation in the hot clouds and a low disk covering factor. The modeled mass is on the order of 10(10) M-circle dot, and the accretion rate is. (M)over dot greater than or equal to 0.2 (M)over dot(Edd). We compare our results with those obtained previously for a hot inner flow geometry.