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

摘要

We modeled the spectral energy distribution of high-redshift radio-quiet quasars (high-z RQQs). We computedudspectra in a patchy corona geometry in which an accretion disk extends to the last stable orbit and the Comptonizingudactive regions (hot clouds) are distributed above the disk. We explored the model parameter space to findudtheoretical parameters that give spectra with an optical/UV luminosity, X-ray loudness, and X-ray photon indexudcompatible with those of high-z RQQs observed with Chandra. We found that a range of solutions is possible,udfrom high-kTe low- to low-kTe high- models. The solutions require a low level of energy dissipation in the hotudclouds and a low disk covering factor. The modeled mass is on the order of 1010 M, and the accretion rate isud˙Mud 0:2 ˙MEdd. We compare our results with those obtained previously for a hot inner flow geometry.