Observational Tests for Accretion Disks in AGN
Session 122 -- AGN: Accretion Disks, Tori and Gas
Oral presentation, Saturday, January 15, 2:15-3:45, Salon IV Room (Crystal Gateway)

## [122.01] Observational Tests for Accretion Disks in AGN

G. Lee (Johns Hopkins University)

\hspace*{5 mm}To produce physically realistic accretion disk spectra, especially in the vicinity of the Lyman edge, I solve the radiative transfer equation for the radiation pressure dominated inner region of the massive thin accretion disks which might exist in AGNs. I analytically solve the vertical structure of the accretion disk by assuming an adiabatic polytrope, and then numerically solve the radiation transfer equation in local thermodynamic equilibrium (LTE). I also consider three possibilities which can change the spectral shape of the Lyman-limit region: relativistic effects produced by the strong gravitational field near the black hole, Comptonization of the emitted disk spectrum by a surrounding hot corona, and the effects of X-ray illumination.

\smallskip The principle result is that the Lyman edge features may be in emission or in absorption, depending on the dominant sources of opacity in the disk atmosphere at various radii. The net contrast in an integrated spectrum is small for a wide range of reasonable parameters, and strong Lyman edges are predicted only in objects that have low luminosity relative to the Eddington limit.

\smallskip I compare the predicted Lyman edge features with the HUT observations of the quasars 3C273 and E1821$+$643 and of the Seyfert 1 galaxy Mrk335 and the HST/FOS observations of the quasar Pks0405-123 to test the observational signatures of accretion disks in AGNs.

\smallskip I also study the multifrequency properties of the continuum radiation from AGNs. I try to infer the unseen EUV continuum, especially the turnover in the UV bump, by emission line diagnostics using the HUT and HST/FOS observations. This is done by running the CLOUDY model for the broad emission lines using the best fitting disk models for the optical-UV spectrum and comparing the calculated line intensities with the measured line properties.