The dependence of the average spectral index of extragalactic sources on luminosity in complete samples selected at different frequencies is shown to vary in a manner that directly reflects their evolutionary properties. In particular, easily recognizable features are introduced by a luminosity dependent evolution and by the presence of a cutoff in the redshift distribution. The expected dependence on luminosity of the average optical to X-ray energy index αox for X-ray selected active galactic nuclei is discussed in some detail.
Differential Information on the Evolution of Extragalactic Sources from Spectral Index Distributions
Danese, Luigi;
1984-01-01
Abstract
The dependence of the average spectral index of extragalactic sources on luminosity in complete samples selected at different frequencies is shown to vary in a manner that directly reflects their evolutionary properties. In particular, easily recognizable features are introduced by a luminosity dependent evolution and by the presence of a cutoff in the redshift distribution. The expected dependence on luminosity of the average optical to X-ray energy index αox for X-ray selected active galactic nuclei is discussed in some detail.File in questo prodotto:
Non ci sono file associati a questo prodotto.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
