Back to Volume
Paper: The AGN/X-Ray Binary Connection
Volume: 360, AGN Variability from X-Rays to Radio Waves
Page: 85
Authors: McHardy, I.; Uttley, P.; Taylor, R.; Papadakis, I.
Abstract: It has long been surmised that AGNs are simply scaled up versions of Galactic black hole X-ray binary systems (GBHs). Here, making extensive use of long term X-ray monitoring observations from RXTE, we examine that scaling, with particular reference to variability characteristics as defined by the powerspectral density (PSD). We find good evidence for scaling of PSD break timescales with mass but note that not all AGNs scale in the same way. AGNs with narrow optical emission lines scale like GBHs in their high state, whereas broad-line AGNs may scale more like GBHs in their low state. Accretion rate variations may account for the difference. Preliminary indications are that the width of the Hβ emission line is better correlated with the PSD break timescale than with the black hole mass, perhaps because of the compensating effect of accretion rate variations on both the line-width and break timescale. We note how the phase lags, and coherence, between different wavebands are very similar for both AGN and GBHs, indicating similar structures in their X-ray emission regions. Shorter timescales of variability, and photons of higher energy, both appear to be both associated with radii closer to the black hole. We also discuss what our RXTE monitoring observations can tell us about the mechanisms of X-ray spectral variability of AGNs.
Back to Volume