Radio and spectroscopic properties of miniature radio- galaxies: revealing the bulk of radio-loud AGN population Ranieri D. Baldi 1, and Alessandro Capetti.

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.



The properties of the radio emission are similar to those of 3C/FRI.

UGC 8745

< α > = 0.7~20kpc


The CoreG show a Core Dominance of a factor 100 larger than the classical 3C/FRI.

CoreG

3CR


The Core Galaxies are Low Excitation Galaxies (LEG) like 3C/FRI.

3CR/LEG

Kew

ley

et a

l. (

2006

)


The nuclear properties of CoreG are similar to those of FRI.

CoreG show a genuine extended radio emission deficit of a factor 100.


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.


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


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: [email protected] > 5 mJy


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

[email protected] > 5 mJy

At z=0.1 Lr = 1039 erg s-1

CoreG


If we use the B2 sample flux selection criterion, low core dominance radio galaxies are the dominant population.

3CR correlation


Extended radio emission is indipendent of the AGN power.

FWHM = 5 arcsec


Are there differences between core dominated sources and FRI?

1.Spectral classification

2.Host mass, morphology and colors

3.Black hole mass distribution


Most of the radio-loud AGN of the SDSS/NVSS sample are low excitation galaxies (LEG).

LEG LEG

HEGHEG

SFG

SFGSFG

AGN


The radio sources of Best et al (2005) sample have nuclei with properties analogous with those of radio-loud LEG.


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


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.

Radio and spectroscopic properties of miniature radio- galaxies: revealing the bulk of radio-loud AGN population Ranieri D. Baldi 1, and Alessandro Capetti.

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