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Ranieri D. Baldi 1 , and Alessandro Capetti 2

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. 2009arXiv0910.4261B. Core Galaxies. 3CR/FRI. CoreG.

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Ranieri D. Baldi 1 , and Alessandro Capetti 2

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  1. 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, INAF 2: Astronomical Observatory of Torino, INAF 2009arXiv0910.4261B

  2. Core Galaxies 3CR/FRI CoreG The Core Galaxies are miniature radio-galaxies. (Balmaverde & Capetti 06 and Balmaverde,Baldi & Capetti 08). Baldi Ranieri D. Leiden, 25/11/2009

  3. Core Galaxies • The aim of this presentation is: • The Optical spectroscopic identification of Core Galaxies . • Analysis of Radio properties. • Comparison with samples of Radio Loud AGN at higher power. Baldi Ranieri D. Leiden, 25/11/2009

  4. Core Galaxies UGC 8745 ~20kpc < α > = 0.7 The properties of the radio emission are similar to those of 3C/FRI. Baldi Ranieri D. Leiden, 25/11/2009

  5. Core Galaxies 3CR CoreG The CoreG show a Core Dominance of a factor 100 larger than the classical 3C/FRI. Baldi Ranieri D. Leiden, 25/11/2009

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

  7. Core Galaxies 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

  8. ..and so? 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

  9. B2 sample From Giovannini et al. (1988) B2 sample, 11 objects with core dominance > 0.1 B2 3CR/FRI B2 B2 CoreG High core dominated sources with higher radio core power! Baldi Ranieri D. Leiden, 25/11/2009

  10. bulk of RL AGN population 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 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

  11. Best et al (2005) sample Seyfert 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 F@1.4GHz > 5 mJy At z=0.1 Lr = 1039 erg s-1 CoreG Baldi Ranieri D. Leiden, 25/11/2009

  12. Selection Bias 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

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

  14. Work in progress • Are there differences between core dominated sources and FRI? • Spectral classification • Host mass, morphology and colors • Black hole mass distribution Baldi Ranieri D. Leiden, 25/11/2009

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

  16. Comparison with LEG 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

  17. How many? Completeness limit The popoulation of SDSS/NVSS AGN sample is flux-limited. The density of objects grows with L1.4-1 down to the completeness limit. Baldi Ranieri D. Leiden, 25/11/2009

  18. Conclusions • Most of the radio sources are highly core dominated. • Selection bias in radio flux-limited sample causes the inclusion only of radio-galaxies with well developped extended structures. • The bulk of RL AGN population is virtually unexplored. • Radio extended emission loses its fundamental role of “calorimeter” of the jet power! • 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: • Link between age and radio extended emission. Young, recurrent? • Influence of environment on the jets properties. Baldi Ranieri D. Leiden, 25/11/2009

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