| Abstract: | Observational constraints on the spectral shape and the sizes of quasar emission regions are in conflict with standard accretion disk models. This contrasts with disk dominated states of X-ray binaries, which seem to be reasonably consistent with theoretical predictions. This difference motivates focusing on aspects of the accretion flow that differ between these two systems. Possibilities include the atomic opacities present in quasars as well as the vastly different ratios of radiation and gas pressure. I will summarize recent results from radiation magnetohydrodynamic numerical simulations that suggest these differences can have significant impact on the structure of quasar accretion flows and offer some speculation on how such effects may resolve conflicts between observation and theory. |
