Bibcode
Scarpa, R.; Urry, C. M.
Referencia bibliográfica
QSO hosts and their environments, Proceedings of an international workshop, held January 10-12, 2001, in Granada, Spain Edited by Isabel Márquez, Josefa Masegosa, Ascencion Del Olmo, Lucas Lara, Emilio García, and Josefina Molina. Dordrecht: Kluwer Academic / Plenum Publishers, 2001 xvii, 376 p. ISBN 0306466627, p.55
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2001
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Descripción
The possibility of radio galaxies being random sample of otherwise
normal elliptical galaxies is tested. Starting with the observed optical
luminosity functions for elliptical galaxies, it is shown that the
probability of an elliptical forming a radio source is a continuous,
increasing function of optical luminosity, precisely proportional to
square of the optical luminosity of the galaxy. Once the probability
function is fixed, the luminosity function of normal elliptical galaxies
is used as input for Monte Carlo simulations that reproduce the
distribution of radio galaxies in the radio-optical luminosity plane.
Our results show that radio galaxies are luminosity biased, but
otherwise random sample of elliptical galaxies. This unified view of
radio and non-radio ellipticals also explains the well known difference
of 0.5 mag in average optical luminosity between FRI and FRII radio
galaxies as a simple selection effect. Specifically, FRII appear
preferentially in smaller galaxies because both radio and optical
luminosity functions are steep, so there is a negligible probability of
observing a powerful radio source associated with a bright galaxy; no
intrinsic physical differences between FRI and FRII host galaxies is
required.