Bibcode
Govoni, F.; Falomo, R.; Fasano, G.; Scarpa, R.
Bibliographical reference
Astronomy and Astrophysics, v.353, p.507-527 (2000)
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1
2000
Journal
Citations
63
Refereed citations
56
Description
We present morphological and photometric properties of 79 low redshift
(z<=0.12) radio galaxies extracted from two radio flux limited
samples of radio sources. All objects are imaged in the R band and for a
subsample we have also obtained B band images. The sample includes
sources of both FRI and FRII radio morphological type. Through the
decomposition of the luminosity profiles and the analysis of the
structural profiles (ellipticity, PA, c4) of the galaxies we are able to
characterize in detail the optical properties of the radio galaxies. It
is found that most of host galaxies are luminous bulge dominated systems
similar to normal giant ellipticals. Some cases of additional disk
components are found whose spheroid-to-disk luminosity ratio is similar
to that found in S0 galaxies. The average absolute magnitude is <
MHOST(tot) >=-24.0 with a clear trend for FRI sources to
be ~ 0.5 mag brighter than FRII galaxies. In about 40% of the objects
observed we find an excess of light in the nucleus that is attributed to
the presence of a nuclear point source whose luminosity is on average ~
1-2% of the total flux of the host galaxy. The luminosity of these
nuclear point sources appears correlated with the core radio power of
the galaxies. Radio galaxies follow the same mu_e - R_e relationship as
normal elliptical galaxies. The distribution of ellipticity, the amount
of twisting and shape of isophotes (boxy, disky) do not differ
significantly from other ellipticals. The evidence for recent
interactions is therefore rather modest. Finally on average radio
galaxies are bluer and have a color dispersion larger than normal
elliptical galaxies, and the average color gradient in radio galaxies
appears slightly steeper than in normal ellipticals. These results
support a scenario where radio emission is weakly related with the
overall properties and/or the activity have negligible effects on the
global characteristics of the host galaxy. Based on observations
collected at the European Southern Observatory, La Silla, Chile. Based
on observations collected at the Nordic Optical Telescope, La Palma.