Cosmological effects on Size Evolution of some Extragalactic Radio Sources and Quasar/Galaxy Unification
Asian Journal of Research and Reviews in Physics,
Page 21-24
DOI:
10.9734/ajr2p/2021/v4i230139
Abstract
We use analytical methods to develop a mathematical model that expresses the relationship between the linear size of some extragalactic radio sources (EGRS) and their redshift . Result shows that , where . For the purpose of obtaining an empirical relation of similar form, we carry out simple linear regression analyses of the observed linear sizes of these EGRS in our sample against their respective observed redshifts. We obtain an empirical relation of the form, , where and for radio-loud quasars and radio galaxies respectively, with correlation coefficients given by, for each of the sources. The correlation is marginal/slight. Comparing the theoretical and empirical relations, we find that the data show an inverse correlation which is similar to the theory. This suggestively indicates presence of cosmological effects on the size evolution of the radio sources. Moreover, we find that similarity in the behavior of the two sources in the plane, simply supports quasar/galaxy unification scheme in which the different observable properties that characterize these two subclasses of radio sources are aspect-dependent.
Keywords:
- Radio sources
- redshift
- galaxies
- quasars
- evolution
- cosmology
- luminosity
- extragalactic
- active galaxies
- unification
How to Cite
References
Mingo BJ, Croston H, Hardcastle MJ. Revisiting the Fanaroff-Riley Dichotomy and Radio Galaxy Morphology with the LOFAR Two-Meter Sky Survey (LoTSS). Monthly Notices of the Royal Astronomical Society. 2019;488:2701–2721.
Hardcastle MJ, Williams WL, Best PN. Radio-loud AGN in the First LoTSS Data Release– The Lifetimes and Environmental impact of Jet-Driven Sources. Astronomy and Astrophysics. 2019;622:A12.
Dabhade P, Gaikwad M, Bagchi J. Discovery of giant radio galaxies from nvss: radio and infrared properties. Monthly notices of the royal astronomical society. 2017;469(3):2886–2906.
Robson I. Active Galactic Nuclei. Praxis Publishing Ltd, England; 1996.
Ezeugo JC. Compact steep spectrum source size and cosmological implication. Quest Journals: Journal of Research in Applied Mathematics. 2021;7(2):01–04.
Ezeugo JC. On cosmic epoch and linear size/luminosity evolution of compact steep spectrum sources. American Journal of Astronomy and Astrophysics. 2021;9(1):8–12.
Readhead AC. Evolution of powerful extragalactic radio sources. In Proceedings of Conference on Quasars and Active Galactic Nuclei, ed. Kohen M, Kellermann K. (USA: National Academy of Sciences, Berkman Center, Irvine), 1995;92:11447–11450.
Kawakatu N, Kino M. The velocity of large-scale jets in a declining density medium. In Proceedings of Conference on Triggering Relativistic Jets, ed. W. H. Lee & E. Ramirez-Ruiz, 2007;27:192–197.
O’Dea CP. The compact steep spectrum sources and gigahertz peaked spectrum radio sources. Publications of the Astronomical Society of the Pacific. 1998;110:493–532.
Murgia M. et al. Synchrotron spectra and ages of compact steep spectrum radio sources. New Astronomy Reviews. 1999;345:769–777.
Ezeugo JC, Ubachukwu AA. The spectral turnover – linear size relation and the dynamical evolution of compact steep spectrum sources. Monthly Notices of the Royal Astronomical Society. 2010;408 :2256 – 2260.
Jackson CA. Radio source evolution and unified schemes. Publications of Astronomical Society of Australia. 1999;16: 124–129.
Ubachukwu AA, Ogwo JN. “Redshift and luminosity dependence of linear size of compact steep spectrum sources and the quasar/galaxy unification scheme. Australian Journal of Physics. 1999;52: 141–146.
-
Abstract View: 46 times
PDF Download: 23 times
