- Conference date: 8−10 Nov 1993
- Location: College Park, Maryland (USA)
We compare the optical to soft X‐ray spectral energy distribution of six bright low‐redshift (0.048<z<0.155) radio‐quiet quasars with models of quasars where the soft excess is interpreted in terms of (a) optically thick thermal emission from the innermost region of an accretion disk in Schwarschild and Kerr geometries, (b) reprocessing from ionized gas. Pure disk models even in a Kerr geometry cannot easily reproduce the observed optical to soft X‐ray energy distribution. The range of parameters which give reasonable predictions is narrow: high inclinations, high accretion rates and central black hole ∼ 108 M ⊙. We consider modifications of the disk models: 1) an underlying power law component extending from the infrared (3 μm) to the X‐ray; 2) reprocessing of the X‐rays. The modified models can explain the optical‐UV and soft X‐ray observations. Free‐free models are discussed by Fiore in these Proceedings.
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