Cosmology from angular size counts of extragalactic radio sources.
Abstract
Cosmological implications of observed angular sizes of extragalactic radio sources are investigated using the log Nlog theta relation (N = number of sources with angular size greater than theta) and the median angular size vs flux density relation derived from several surveys. A technique is outlined for estimating the expected relations for a uniform distribution of sources in space. It is found that for angular sizes of at least 100 arcsec, the slope of the N(theta) relation is almost independent of cosmological model and sourcesize distribution but depends strongly on the radio luminosity function. It is shown that the angularsize data give independent evidence for evolution in source properties with epoch. Data for simple evolutionary schemes are fitted to the steadystate and Einsteinde Sitter cosmologies. It is found that the steadystate model cannot easily explain the data, while the Einsteinde Sitter model gives reasonable fits.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 September 1975
 DOI:
 10.1093/mnras/172.3.513
 Bibcode:
 1975MNRAS.172..513K
 Keywords:

 Astronomical Models;
 Cosmology;
 Extragalactic Radio Sources;
 Quasars;
 Size Determination;
 Angular Distribution;
 Galactic Evolution;
 Luminous Intensity;
 Radio Galaxies;
 Stellar Luminosity;
 Astrophysics