Models of optical/UV continuum in AGN: constraints from the NGC 5548 monitoring campaign

Abstract

We analyse the data from the optical/IUE observational campaign of the Seyfert galaxy NGC 5548 in the context of 10 phenomenological models. On the basis of the optical/UV data as well as constraints from the X-ray observations we can favour one model of the nucleus: an accretion disc with an inner radius cutoff surrounded by a hot corona. The second acceptable model for optical/UV data is a distribution of optically thin clouds. However, X-ray constraints which were crucial in the analysis of disc type models could not have been applied; further development of this model is necessary.

The power density spectrum of NGC 5548 and the nature of its variability

“…The mass of the black hole in NGC 5548 is most probably within the range from 6×10 7 to 1.4×10 8 M (see e.g. Loska & Czerny 1997;Kuraszkiewicz, Loska & Czerny 1997 and references therein). Therefore, we can adopt the value of 10 8 M as representative.…”

“…These data allowed researchers to formulate the first phenomenological models of the time behaviour of the flow in this object (e.g. Rokaki, Collin‐Souffrin & Magnan 1993;Loska & Czerny 1997;Magdziarz et al 1997).…”

Universal spectral shape of high accretion rate AGN

“…Optical/UV spectra were modeled by introducing an irradiation of the outer disk by the innermost part (e.g. Loska & Czerny 1997;Soria & Puchnarewicz 2002). However, those modifications were basically arbitrary from the point of view of our knowledge of the accretion process, and therefore do not explain the reason why the resulting spectral shape is so universal.…”

Universal spectral shape of high accretion rate AGN

“…Rokaki et al 1993;Loska & Czerny 1997;Nayakshin & Kazanas 2002) or GBH (e.g. Cannizzo 2000, mostly concentrating on illumination of the disk by an X-ray source, arbitrarily located high above the disk.…”