Astronomy and Astrophysics – Astrophysics
Scientific paper
1999-10-25
Astronomy and Astrophysics
Astrophysics
8 pages, 4 figures, uses nfraconf.sty. To appear in the proceedings of NFRA conference "Perspectives of radio astronomy: Scien
Scientific paper
Giant radio sources form the linear size extreme of the extra-galactic radio source population. Using the WENSS survey, we have selected a complete sample of these sources. We have investigated the properties of their radio structures. We find, among other things, that these sources are old (50-100 Myr) and have higher advance velocities than smaller sources of similar radio power. We find pressure gradients in their radio lobes, suggesting that the lobes are still overpressured with respect to the environment. Further, we find no evidence for a cosmological evolution of the radio lobe pressures with increasing redshift, at least up to $z\sim 0.4$, other than that caused by selection effects. We argue that a much fainter sample of giant sources than currently available is needed to constrain the pressure in their environments, the IGM. Another extremely important discovery is that of a population of radio sources with a so-called `double-double' structure, i.e. that of a small two-sided radio source embedded inside a much larger two-sided structure. We argue that these sources result from an interrupted central jet-forming activity. As such, they are the most convincing examples of radio sources with a history of interrupted activity, yet. Since the inner lobes advance within the outer lobes, high resolution low frequency ($\sim 200$ MHz) polarization studies may reveal the constituents of radio lobes and cocoons. We thus argue for a SKA design that can provide low-frequency images at arcsec resolution, but which is also sensitive to structures as large as a few tens of arcminute on the sky.
de Bruyn Ger A.
der Laan van H.
Kaiser Christian R.
Mack Karl-Heinz
R"ottgering Huub J. A.
No associations
LandOfFree
Giant and `double-double' radio galaxies: Implications for the evolution of powerful radio sources and the IGM does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Giant and `double-double' radio galaxies: Implications for the evolution of powerful radio sources and the IGM, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Giant and `double-double' radio galaxies: Implications for the evolution of powerful radio sources and the IGM will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-2224