High redshift radio quiet quasars -- exploring parameter space of accretion models. Part II: patchy corona model

Abstract

We modeled the spectral energy distribution (SED) of high redshift radio quiet quasars (high-z RQQs). We computed spectra in a patchy corona geometry where 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 the optical/UV luminosity, the X-ray loudness, and the 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-$kT_{\rm e}$ low-$τ$ to low-$kT_{\rm e}$ high-$τ$ models. The solutions require low level of energy dissipation in the hot clouds and low disk covering factor. The modeled mass is of the order of $10^{10}$ Solar masses and the accretion rate is $\dot{M} > 0.2$ Eddington rate. We compare our results to those obtained previously for hot inner flow geometry.