APPLICATION OF THE LOH-SPILLAR COSMOLOGICAL TEST TO QUASARS

The Loh-Spillar (L-S) cosmological test relies on a knowledge of the l ocal space density of a population of test particles and a luminosity function for that population whose redshift dependence can be describe d by pure luminosity evolution. Using a newly derived local luminosity function for active galactic nuclei (AGNs) from.a complete X-ray-sele cted sample of 78 objects at z < 0.15 and the previously known propert y of complete quasar samples to apparently exhibit pure luminosity evo lution, we apply the L-S test to a combined sample of 447 quasars and derive a value of OMEGA0 = 0.2(+0.15/-0.1) (1 sigma errors) assuming l ambda0 = 0 or OMEGA0 = 0.4(+0.1/-0.06) in a cosmologically flat model (OMEGA0 + lambda0 = 1). The formal errors are remarkably small but do not account for systematic errors which are present if any of the requ irements of the L-S technique are not met. Alternatively, we can state that the adopted pure luminosity evolution model for the evolution of the quasar luminosity function, including a normalization of the loca l AGN population at the same level as that of high-redshift quasars, i s inconsistent with OMEGA0 = 1 at a high level of significance.