Query : 2010A&A...519A..48B

2010A&A...519A..48B - Astronomy and Astrophysics, volume 519, A48-48 (2010/9-1)

Spectro-photometric properties of the bulk of the radio-loud AGN population.


Abstract (from CDS):

In a previous paper we showed that the radio sources selected by combining large area radio and optical surveys, have a strong deficit of radio emission with respect to 3CR radio-galaxies matched in line emission luminosity. We argued that the prevalence of sources with luminous extended radio structures in high flux-limited samples is due to a selection bias. Sources with low radio power form the bulk of the radio-loud AGN population but are still virtually unexplored. We here analyze their photometric and spectroscopic properties. From the point of view of their emission lines, the majority of the sample are Low Excitation Galaxies (LEG), similar to the 3CR objects at the same level of line luminosity. The hosts of the LEG are red, massive (10.5≲log M*/M≲12) Early-Type Galaxies (ETG) with large black hole masses (7.7≲log MBH/M≲ 9), statistically indistinguishable from the hosts of low redshift 3CR/LEG sources. No genuine radio-loud LEG could be found associated with black holes with a mass substantially smaller than 108M or with a late type host. The fraction of galaxies with signs of star formation (∼5%) is similar to what is found in both the quiescent ETG and 3CR/LEG hosts. We conclude that the deficit in radio emission cannot be ascribed to differences in the properties of their hosts. We argue that instead this could be due to a temporal evolution of the radio luminosity. A minority (∼10%) of the sample show rather different properties; these are associated with low black hole masses, with spiral galaxies, or with a high excitation spectrum. In general these outliers are the result of the contamination from Seyfert galaxies and from those where the radio emission is powered by star formation. For the objects with high excitation spectra there is no clear discontinuity in either the host or nuclear properties because they include radio-quiet as well as radio-loud AGN.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: elliptical and lenticular, cD - galaxies: photometry - galaxies: jets

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 3C 84 Sy2 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 3937 3
2 3C 198.0 AGN 08 22 31.9510001544 +05 57 06.787089972   18.04 17.33     ~ 128 0
3 3C 236.0 BLL 10 06 01.75023017 +34 54 10.4016113   15.97       ~ 442 2
4 NVSS J133453-013240 rG 13 34 53.3663014800 -01 32 38.530647924   18.589   18.455   ~ 9 0
5 MCG+06-37-020 Sy2 17 00 07.1726469072 +37 50 22.237695420   18.40 17.66     ~ 25 0

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