Astrophysics and Space Science

, Volume 228, Issue 1–2, pp 195–202 | Cite as

The implications of intrinsic luminosity evolution on the value of the density parameter (Ω) and the evolution of radio sizes of radio galaxies and quasars

  • A. A. Ubachukwu


The implications of the intrinsic luminosity evolution with cosmological epoch on the value of the density parameter (Ω) and evolution of radio sizes of extragalactic radio sources have been considered. It is shown that a power law evolution model of the sortP ∼ (1 +z) β can be used to contrain the value of Ω. In the presence of a strong luminosity evolution, the model yields an upper limit of Ω ∼ 0.5.

It is also shown that the angular diameter redshift (θ – z) relation for quasars can be interpreted in terms of the assumed luminosity evolution combined with a luminosity-linear size correlation with little or no linear size evolution required. On the other hand, strong linear size evolution is needed to explain theθ – z data for radio galaxies independent of luminosity.


Evolution Model Radio Source Linear Size Density Parameter Radio Galaxy 
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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • A. A. Ubachukwu
    • 1
  1. 1.Space Research Centre, Department of Physics and AstronomyUniversity of NigeriaNsukkaNigeria

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