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		| Paper: | 
		The Fundamental Plane of Black Hole Activity and the Census of the Local Black Holes' Population | 
	 
	
		| Volume: | 
		311, AGN Physics with the Sloan Digital Sky Survey | 
	 
	
		| Page: | 
		95 | 
	 
	
		| Authors: | 
		Merloni, A. | 
	 
	
	
		| Abstract: | 
		Studying a sample of both strongly and weakly active galactic nuclei with measured masses and 5 GHz and 2-10 keV core luminosities, together with a few galactic black holes simultaneously observed in the radio and X-ray bands, Merloni, Heinz, and Di Matteo (2003) showed that these sources are correlated through a "fundamental plane"' relationship in three-dimensional (log LR, log LX, log M) space. Here I elaborate on how such a relationship can be used to infer directly mass and accretion rate of any black hole given its radio and X-ray fluxes, complementing the information obtained from optical/UV surveys. As an example, I show how the local X-ray and radio luminosity functions, coupled with the black hole mass function derived from the M − σ relation, provide us with an accretion rate function. We found that the typical X-ray Eddington ratio of an active black hole at redshift zero is about 5 × 10−4. | 
	 
	
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