1 research outputs found
The new sample of giant radio sources III. Statistical trends and correlations
In this paper we analyse whether `giant' radio galaxies (GRGs) differ from
`normal'-size galaxies (NSGs) except for the linear extent of their radio
structure. We compare a number of properties of GRGs with the corresponding
properties of NSGs, and analyse the statistical trends and correlations of
physical parameters, homogeneously determined for the sources, with their
`fundamental' parameters. Using the Pearson partial-correlation test on the
correlation between two variables in the presence of one or two other
variables, we examine which correlation is the strongest. The analysis clearly
shows that GRGs do not form a separate class of radio sources. They most likely
evolve with time from smaller sources, however under specific circumstances.
Analysing properties of GRGs and NSGs together, we find that (i) the core
prominence does not correlate with the total radio luminosity (as does the core
power), but it anti-correlates with the surface brightness of the lobes of
sources, (ii) the energy density (and possibly the internal pressure) in the
lobes is independent of redshift for constant radio luminosity and size of the
sources, (iii) the equipartition magnetic-field strength, transformed into
constant source luminosity and redshift, strongly correlates with the source
size. We argue that this B_{eq} - D correlation reflects a more fundamental
correlation between B_{eq} and the source age, (iv) both the rotation and
depolarisation measures suggest Faraday screens local to the lobes of sources,
however their geometry and the composition of intervening material cannot be
determined from the global polarisation characteristics.Comment: 10 pages, 8 figures, 6 tables. Accepted for publication in A&