Astronomy and Astrophysics – Astrophysics
Scientific paper
Feb 1985
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1985a%26a...143..277d&link_type=abstract
Astronomy and Astrophysics (ISSN 0004-6361), vol. 143, no. 2, Feb. 1985, p. 277-291. Sponsorship: Consiglio Nazionale delle Rice
Astronomy and Astrophysics
Astrophysics
13
Cosmology, Extragalactic Radio Sources, Galactic Nuclei, Quasars, Visible Spectrum, X Ray Sources, Active Galactic Nuclei, Astronomical Models, Evolution (Development), Luminosity, Radio Spectra, Red Shift, Seyfert Galaxies, Space Density
Scientific paper
Luminosity-dependent-density (LDD) and pure luminosity (L) cosmological evolution models are evaluated comparatively on the basis of trial fittings to published observational data on steep-spectrum and flat-spectrum radio sources, optically selected QSOs, and X-ray-selected active galactic nuclei. The model formulas are given; the data selection is explained; and the data, model predictions, and evolution functions are presented in tables and graphs and discussed. LDD-model evolution functions strongly increasing with luminosity are found to give good fits to all observations, with probably nonintrinsic differences in the steepness of the dependence for steep and flat spectra and a decline in the evolution functions of radio sources at cutoff redshift z(c) = about 3. In the L-model fits, all sources except a nonevolving low-lumnosity group of radio sources are found to evolve on time scales of the order 20-25 percent of the Hubble time, and good fits are also obtained using luminosity-dependent time scales with weak evolution at low luminosity.
Danese Lugi
de Zotti Gainfranco
Franceschini Alberto
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