Ranieri D. Baldi 1 , and Alessandro Capetti 2
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Radio and spectroscopic properties of miniature radio-galaxies: revealing the bulk of
radio-loud AGN population
Ranieri D. Baldi1, and Alessandro Capetti2
1: University of Torino, INAF2: Astronomical Observatory of Torino, INAF2009arXiv0910.4261B
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The Core Galaxies are miniature radio-galaxies.
(Balmaverde & Capetti 06 and Balmaverde,Baldi & Capetti 08).
CoreG
3CR/FRI
The aim of this presentation is:
1. The Optical spectroscopic identification of Core Galaxies .
2. Analysis of Radio properties.
3. Comparison with samples of Radio Loud AGN at higher power.
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The properties of the radio emission are similar to those of 3C/FRI.
UGC 8745
< α > = 0.7~20kpc
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The CoreG show a Core Dominance of a factor 100 larger than the classical 3C/FRI.
CoreG
3CR
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The Core Galaxies are Low Excitation Galaxies (LEG) like 3C/FRI.
3CR/LEG
Kew
ley
et a
l. (
2006
)
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The nuclear properties of CoreG are similar to those of FRI.
CoreG show a genuine extended radio emission deficit of a factor 100.
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
Deficit in radio extended emission??
But, their radio core is fainter than that typical of FRI/LEG.
Let us look for other core dominated sources in sample of higher power.
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
High core dominated sources with higher radio core power!
From Giovannini et al. (1988) B2 sample, 11 objects with
core dominance > 0.1
B2
CoreG
3CR/FRI
B2
B2
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
Our interpretation:
The prevalence of low core dominance sources in The prevalence of low core dominance sources in low frequency fluxlow frequency flux
limited samples is due to a selection bias.limited samples is due to a selection bias.
To test this scenario..
Best et al (2005) of RL AGN: crossmatching the 212000 galaxies drawn from the SDSS DR2 with the NVSS and FIRST radio surveys.Selection: F@1.4GHz > 5 mJy
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The bulk of the population of this SDSS/NVSS AGN sample shows a large deficit of total radio emission, similar to that observed in CoreG.
3CR correlation
Seyfert
F@1.4GHz > 5 mJy
At z=0.1 Lr = 1039 erg s-1
CoreG
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
If we use the B2 sample flux selection criterion, low core dominance radio galaxies are the dominant population.
3CR correlation
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
Extended radio emission is indipendent of the AGN power.
FWHM = 5 arcsec
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
Are there differences between core dominated sources and FRI?
1.Spectral classification
2.Host mass, morphology and colors
3.Black hole mass distribution
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
Most of the radio-loud AGN of the SDSS/NVSS sample are low excitation galaxies (LEG).
LEG LEG
HEGHEG
SFG
SFGSFG
AGN
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The radio sources of Best et al (2005) sample have nuclei with properties analogous with those of radio-loud LEG.
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
The popoulation of SDSS/NVSS AGN sample is flux-limited. The density of objects grows with L1.4
-1 down to the completeness limit.
Completeness limit
Baldi Ranieri D. Leiden, 25/11/2009 Baldi Ranieri D. Leiden, 25/11/2009
1. Most of the radio sources are highly core dominated.
2. Selection bias in radio flux-limited sample causes the inclusion only of radio-galaxies with well developped extended structures.
2. The bulk of RL AGN population is virtually unexplored.
4. Radio extended emission loses its fundamental role of “calorimeter” of the jet power!
5. the SDSS/NVSS AGN sample is composed of quiescent giant elliptical, MBH~108-109, LEG, with nuclei similar to those of 3C FRI/LEG.
Possible interpretations for low extended power:
1. Link between age and radio extended emission. Young, recurrent?
2. Influence of environment on the jets properties.
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