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

1 Radio and spectroscopic properties of miniature radio- galaxies: revealing the bulk of radio-loud AGN population Ranieri D. Baldi 1, and Alessandro Capetti 2 1: University of Torino, INAF 2: Astronomical Observatory of Torino, INAF 2009arXiv B

2 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

3 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

4 The properties of the radio emission are similar to those of 3C/FRI. UGC 8745 = 0.7 ~20kpc

5 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

6 Baldi Ranieri D. Leiden, 25/11/2009 The Core Galaxies are Low Excitation Galaxies (LEG) like 3C/FRI. 3CR/LEG Kewley et al. (2006)

7 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.

8 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.

9 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

10 Baldi Ranieri D. Leiden, 25/11/2009 Our interpretation: The prevalence of low core dominance sources in low frequency flux limited samples is due to a selection bias. To test this scenario.. Best et al (2005) of RL AGN: crossmatching the galaxies drawn from the SDSS DR2 with the NVSS and FIRST radio surveys. Selection: > 5 mJy

11 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 > 5 mJy At z=0.1 L r = erg s -1 CoreG

12 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

13 Baldi Ranieri D. Leiden, 25/11/2009 Extended radio emission is indipendent of the AGN power. FWHM = 5 arcsec

14 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

15 Baldi Ranieri D. Leiden, 25/11/2009 Most of the radio-loud AGN of the SDSS/NVSS sample are low excitation galaxies (LEG). LEG HEG SFG AGN

16 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.

17 Baldi Ranieri D. Leiden, 25/11/2009 The popoulation of SDSS/NVSS AGN sample is flux-limited. The density of objects grows with L down to the completeness limit. Completeness limit

18 Baldi Ranieri D. Leiden, 25/11/ 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, M BH ~ , 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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