International Astronomy and Astrophysics Research Journal

Cosmological Evolution Effects on the Galactic Size Using Compact Steep Spectrum Sources

Ezeugo Jeremiah Chukwuemerie *

Department of Physics and Industrial Physics, Nnamdi Azikiwe University, Awka, Nigeria.

*Author to whom correspondence should be addressed.

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Abstract

Here, we use statistical methods of analyses to find the effects of cosmological evolution on the galactic sizes using compact steep spectrum (CSS) sources. We have done this by carrying out linear regression analysis of observed source linear sizes (D) of CSS quasars against their observed redshifts (z) . Result shows that D has an inverse relationship with z ; correlation coefficient \((r \approx 0.4)\) is marginal. If D is taken to be distance between any two points within a galaxy, this result may be taken to mean cosmological evolution dependence on distance between any two points in an interstellar medium (ISM). In addition, the result of linear size/luminosity \((D-P)\) data indicates that CSS source size shows an inverse power-law function with luminosity. We notice that source luminosity may have a direct link with dynamical evolution; because, it  (P) has been shown to have a direct relationship with source kinetic power. Therefore combining the effects of dynamical evolution and cosmological evolution, we find the relation, \(D \sim P^{-0.16}(1+z)^{-1.52}\). This suggestively implies combined effects of dynamical evolution \(\left(D_{P}\right)\) and cosmological evolution  \(\left(D_{Z}\right)\) on a CSS source size. Finally, we estimate the percentage effects of both  \(\left(D_{P}\right)\) and \(\left(D_{Z}\right)\) on the CSS source size. Results indicate that the effect due to dynamical evolution is ; while that due to cosmological evolution is . From the foregoing, the result obtained for  cosmological evolution simply shows that if D is taken to be a distance separating any two positions in any ISM, then the evolution (or expansion) of this distance is appreciable when compared to other forms of evolution. Therefore, we may conclude by stating that as the universe is expanding with time, each galaxy is also expanding in size.

Keywords: Cosmological evolution, linear size, galactic size, luminosity, radio sources, quasars, dynamical evolution, steep spectrum

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