EDP Sciences
Free access
Volume 399, Number 3, March I 2003
Page(s) 829 - 832
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20021888

A&A 399, 829-832 (2003)
DOI: 10.1051/0004-6361:20021888

Evidence for the class of the most luminous quasars

IV. Cosmological Malmquist bias and the $\Lambda$ term
P. Teerikorpi

Tuorla Observatory, University of Turku, 21500 Piikkiö, Finland
(Received 6 November 2002 / Accepted 3 December 2002)

We study if the evidence for the optically luminous subclass of radio quasars (Teerikorpi 2000, 2001), depends on the Friedmann model used, especially on the presence or not of a $\Lambda$ term. Previously this grouping, with distinct properties, was found at $M_{V}
\approx -26.0 + 5\log h$ ( $\Omega_m = 1$, $\Omega_{\Lambda} = 0$). The cosmological Malmquist bias approach shows that the member candidates, separated by an empty luminosity range from fainter quasars, as well or better appear in the currently favoured flat models with a non-zero $\Lambda$. We briefly illustrate the effect of $\Lambda$ on the Malmquist bias, depending on the steeper volume derivative and longer luminosity distance in $\Lambda$ models.

Key words: quasars: general -- cosmology: observations

© ESO 2003