On Size Evolution / Radiated Power of Extragalactic Radio Sources and Implication
Ezeugo Jeremiah Chukwuemerie *
Department of Physics and Industrial Physics, Nnamdi Azikiwe University, Awka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
We have applied in this work, statistical methods of analyses to find empirically some effect posed by source expansion on radiated power of extragalactic radio sources. The subclasses of the sources used are radio-loud quasars and radio galaxies. We have done this by carrying out linear regression analyses of observed source angular sizes \((\theta)\) of the quasars against their respective observed redshifts \((z)\) ; as well as, observed source luminosities \((P)\) against their respective observed redshifts. For the quasars, result indicates that with good correlation coefficient \((r \approx 0.5)\) observed angular size shows an inverse relationship with observed redshift, and is given by \((\theta \sim(1+z)^{-1.9}\). For the galaxies, the result indicates similar trend; we obtain \theta \sim(1+z)^{-3.7}, where \(r \approx 0.6\) (which is also a good correlation). Moreover, on the \(P-z\) plane, we obtain a direct relationship given by \(P \sim(1+z)^{0.04}\) for the quasars; where \(r \approx 0.8\) (which is a good correlation). However, for the galaxies, luminosity/redshift relationship is poor \(\text { (with } r \approx 0.1 \text { ) }\). This poor correlation may possibly have stemmed from lack of observation of galaxies at high redshifts unlike observation of their quasar counterparts. The \(\theta / z\) relationships for the quasars and the galaxies simply indicate positive source size evolution with time. However, the converse is the case for \(P / Z\) relationship – it shows negative source luminosity evolution with time. These results suggestively indicate that extragalactic radio sources, though small scaled at earlier epoch, were more powerful sources than what they are at present epoch. Their luminosity/angular size relation is given by \(P \sim \theta^{-0.01}\). Therefore, conclusively the results suggestively indicate that the mechanisms of size evolution of these sources simply bring about diminution effect on their radiated power.
Keywords: Angular size, luminosity, redshift, radio sources, quasars, galaxies, extragalactic, epoch, evolution
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References
Ezeugo JC. Jet in the more extended radio sources and unification with compact steep spectrum sources. The Pacific Journal of Science and Technology. 2021;22:14–19.
Ubah OL, Ezeugo JC. Relativistic jet propagation: Its evolution and linear size cosmic dilation. International Astronomy and Astrophysics Research Journal. 2021;3(3):1–6.
Urry CM. AGN unification: An update. Astronomical Society of the Pacific conference series 1; 2004.
Readhead AC. Evolution of powerful extragalactic radio sources. In proc. Colloquium on Quasars and Active Galactic Nuclei, ed. Kohen, M., and Kellermann, K. (USA: National Academy of Sciences, Berkman Center, Irvine). 1995;92:11447–11450.
Robson I. Active Galactic Nuclei, John Wiley and Sons Ltd, England; 1996.
Jackson JC. Radio source evolution and unified schemes. Publications of Astronomical Society of the Pacific. 1999;16:124–129.
Kawakatu N, Kino M. The velocity of large-scale jets in a declining density medium. In Serie de Conferencias. Triggering Relativistic Jets, ed. W.H. Lee and E. Ramirez-Ruiz. 2007;27:192–197.
Mahatma VH, Hardcastleand MJ, Williams WL. LoTSS DR1: Double-double Radio Galaxies in the HETDEX Field. Astronomy and Astrophysics. 2019;622: A13.
Mingo B, Croston JH, 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 WL, 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.
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.
Nilson K. Kinematical models of double radio sources and unified scheme. Monthly Notices of the Royal Astronomical Society. 1998;132:31–37.
Fanti C, Fanti R, Dallacasa D, Schillizzi RT, Spencer RE, Stanghellini C. Are compact steep spectrum sources young? Astronomy and Astrophysics. 1995;302: 317–326.
Ezeugo JC. On the intergalactic media densities, dynamical ages of some powerful radio sources and implications. Journal of Physical Sciences and Application. 2021;11(1):29–34.
Ezeugo JC. Compact steep spectrum source size and cosmological implication. Journal of Research in Applied Mathematics. 2021;7(2):1–4.
Ezeugo JC. Compact steep-spectrum radio sources and ambient medium density. International Journal of Astrophysics and Space Science. 2015;3(1):1–6.
Ezeugo JC. On the dependence of spectral turnover on linear size of compact steep-spectrum radio sources. International Journal of Astrophysics and Space Science. 2015;3(2):20–24.
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.