Astronomy and Astrophysics – Astrophysics
Scientific paper
Aug 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994apj...431...52s&link_type=abstract
The Astrophysical Journal, Part 1, vol. 431, no. 1, p. 52-68
Astronomy and Astrophysics
Astrophysics
5
Active Galactic Nuclei, Cosmology, Galactic Evolution, Hubble Constant, Red Shift, Statistical Tests, Astronomical Models, Astrophysics, Stellar Luminosity, X Ray Astronomy
Scientific paper
The Hubble (linear) and Lundmark (homogeneous) quadratic redshift-distance laws are subjected to statistically efficient parallel tests on the basis of the complete sample of X-ray active galactic nuclei of Gioia et al. (1990), Maccacaro et al. (1991), and Stocke et al. (1991). The samples treated to this end consist of bright flux-limited subsamples in a variety of redshift ranges. Luminosity functions are estimated by an optimal non-parametric procedure that makes no assumptions regarding the spatial distribution of the sources and is compatible with missing redshifts. It assumes only that the discrimination against objects on the basis of flux is inconsequential above a suitable limit, which may depend on the position of the object. This is subject to a posteiori testing, which is provided. The Hubble and Lundmark laws are tested in successively higher redshift ranges up to z-0.4, within which range Maccacaro et al. find only weak evolution. Directly observed quantities are compared with the predictions of both cosmologies, and objective statistical significance levels estimated. The Hubble law appears inconsistent with the observations, unless evolution effectively equivalent to its replacement by the Lundmark law is postulated. For example, the dispersion in log flux invariably exceeds the observed value, as does also the correlation of log luminosity with redshift. The Lundmark law fits the observations closely and moreover predicts that the predictions of the Hubble law will be deviant in the amounts observed. Very bright optical subsamples give similar results. In the full redshift range of the sample, z less than 3, the chronometric predictions for directly observed quantities, which involve no adjustable parameters such as q zero, and which assume no evolution, are quite accurate. The large deviations of the Friedmann predictions from these values, which may be ascribed to unobservable evolutionary effects, are statistically coincident with the chronometric predictions for the results of analysis predicted on Friedmann cosmology.
Nicoll J. F.
Segal I. E.
Wu Patrick
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