Evidence for central supermassive objects

Evidence for central supermassive objects - Evidence for...

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Unformatted text preview: Evidence for central supermassive objects More or less direct mass determinations of the central objects in AGN have been used to support the notion of accretion onto (super)massive black holes. The techniques have included Estimates of the BLR radius combined with its velocity extent. This can be taken as a virial-like estimator of the total mass. The velocity scale is straightforward, once you decide which moment of the profile represents a characteristics velocity at what radius. The distance from the center can be deduced from ionization-parameter arguments (which turns out to have very poor error behavior at high densities) or from variability studies. A famous example was the NGC 4151 paper from a long IUE monitoring campaign, by Ulrich et al. 1984 (MNRAS 206, 221), most notable for a typo in the value of G they used. An erratum (MNRAS 209, 479) includes, "It has been drawn to our attention by Dr. N.Y. Chen of Sulzer Brothers Limited, Winterthur, Switzerland, that we made an arithmetical error of a factor 10 in our estimate of the...
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