2004/11/12 by J. Machalski, K. T. Chyzy, K. T. Chyży +4
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0411330
14 pages, 4 figures, 1 tables, Acta Astronomica in press
arxiv created 2004/11/12 · openalex publication_date 2004/11/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The time evolution of `fiducial' radio sources derived from fitting the dynamical model of Kaiser et al. (1997) is compared with the observational data for the `clan' sources found in the sample of giant and normal-size FRII-type sources published Paper I (Machalski et al. 2004). Each `clan' comprises 3, 4 or 5 sample sources having similar values of the two basic physical parameters: the jet power Q0 and central density of the galaxy nucleus rho0 (determined in Paper I) but different ages, radio luminosities and axial ratios. These sources are considered as the `same' source observed at different epochs of its lifetime and used to fit the evolutionary luminosity-size (P-D) and energy density-total energy (uc-Etot) tracks derived from the model for a `fiducial' source with Q0 and rho0 equal to the means of relevant values obtained for the `clan' members, as well as to constrain the evolutionary model of the source dynamics used. In the result we find that (i) The best fit is achieved when the Kaiser et al.'s model is modified by allowing an evolution of the sources' cocoon axial ratio with time as suggested by Blundell et al. (1999). (ii) A slow acceleration of the average expansion speed of the cocoon along the jet axis is suggested by the `clan' sources. We argue that this acceleration, although minor, may be real and some supporting arguments come from the well known hydrodynamical considerations.