2006A&A...454...95M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.12CEST15:54:06

2006A&A...454...95M - Astronomy and Astrophysics, volume 454, 95-102 (2006/7-4)

The new sample of giant radio sources. III. Statistical trends and correlations.

MACHALSKI J. and JAMROZY M.

Abstract (from CDS):

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: the redshift, radio luminosity, and linear size. 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. Thus, in the analysed samples, there is no evidence for a cosmological evolution of the IGM pressure in the form pIGM∝(1+z)5; (iii) the equipartition magnetic-field strength, transformed into constant source luminosity and redshift, strongly correlates with the source size. We argue that this Beq-D correlation reflects a more fundamental correlation between Beq 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. The significant correlation between the depolarisation measure and the linear size can be explained by less dense IGM surrounding the lobes (or cocoon) of GRGs than that in the vicinity of NSGs.

Abstract Copyright:

Journal keyword(s): radio contiuum: galaxies - galaxies: kinematics and dynamics

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 2MASX J08312752+3219270 EmG 08 31 27.521 +32 19 27.06   16.0       ~ 76 2
2 3C 244.1 QSO 10 33 33.982 +58 14 35.85   19.0 19.0     ~ 174 1
3 3C 267 rG 11 49 56.5 +12 47 19   22.5       ~ 146 2
4 3C 319.0 rG 15 24 05.60 +54 28 18.4   18.5       ~ 143 1
5 4C 55.31 rG 15 35 01.20 +55 36 48.0   23       ~ 112 1
6 3C 337 QSO 16 28 53.9 +44 19 03   20.0       ~ 138 1
7 4C 31.47 rG 17 28 20.134 +31 46 03.01   15.5       ~ 124 1
8 3C 437 rG 21 47 25.10 +15 20 37.0   23       ~ 120 2

    Equat.    Gal    SGal    Ecl

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2020.07.12-15:54:06

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