_____________________________________________________________________________________________________ *Corresponding author: E-mail: chuksemerie@yahoo.com; International Astronomy and Astrophysics Research Journal 4(1): 44-52, 2022; Article no.IAARJ.84174 Looking into Dark Energy Effect on the Extragalactic Radio Quasar Luminosity Evolution Ezeugo Jeremiah Chukwuemerie a* a Department of Physics and Industrial Physics, Nnamdi Azikiwe University, PMB-5025, Awka, Nigeria. Author’s contribution The sole author designed, analysed, interpreted and prepared the manuscript. Article Information Open Peer Review History: This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers, peer review comments, different versions of the manuscript, comments of the editors, etc are available here: https://www.sdiarticle5.com/review-history/84174 Received 14 January 2022 Accepted 18 March 2022 Published 22 March 2022 ABSTRACT In this work, we use both analytical methods and statistical methods to find effect of dark energy on the extragalactic radio (EGR) quasar luminosity evolution. We carry out linear regression analysis of observed source linear sizes  of the more extended radio quasars against their corresponding observed redshifts  in our sample. Also, we carry out similar analysis on the observed linear sizes of compact steep spectrum (CSS) quasars against their corresponding observed redshifts. Results of the regressions indicate that if we take  to be distance between any two positions in the environment in which the source is domiciled, then cosmic evolution relates inversely with the distance between the two positions in question – it is given by     ; where    and  for the more extended EGR quasars and CSS quasars respectively. Since “a higher redshift implies an earlier epoch”, and redshift has a direct dependence on expansion velocity between any two points in space, the results of the analyses simply suggest that at earlier epoch, the expansion rate of the universe was higher. Our results also indicate that the effect of cosmic evolution in the extended EGR quasars is more than the effect in the CSS quasars       . Since the linear sizes of the more extended EGR quasars are projected into the intergalactic medium (IGM), while the linear sizes of the CSS quasars are domiciled within their individual host galaxies (i.e. the interstellar medium [ISM]), the result      can be interpreted to mean that cosmic evolution shows greater effect in the IGM (i.e. more rarefied medium) than in the ISM (i.e. less rarefied medium). Hence, from the results of the analyses, we may state that if dark energy is defined as the intrinsic tendency of vacuum (or free space) to increase in volume, then the Original Research Article