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		| Paper: | 
		The cosmological evolution and luminosity function of X-ray selected active galactic nuclei | 
	 
	
		| Volume: | 
		21, The Space Distribution of Quasars | 
	 
	
		| Page: | 
		150 | 
	 
	
		| Authors: | 
		della Ceca, Roberto; Maccacaro, Tommaso | 
	 
	
	
		| Abstract: | 
		A sample of more than 420 X-ray selected active galactic nuclei was used to derive the local observed X-ray luminosity function (XLF) and the XLF in different redshift shells up to z = 2. The two most common evolutionary forms were considered and the data were analyzed within the framework of luminosity evolution models. For exponential evolution functions luminosity-dependent evolution is required but the simpler pure luminosity evolution function is acceptable if the evolution function has the power law form. A de-evolved XLF was derived using the sample. A good fit was obtained with a broken power law. Constraints imposed on the cosmological evolution at redshifts greater than two by data from the ROSAT mission are discussed. | 
	 
	
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