Astronomy and Astrophysics, volume 440, 73-84 (2005/9-2)
The host galaxy/AGN connection in nearby early-type galaxies. Sample selection and hosts brightness profiles.
CAPETTI A. and BALMAVERDE B.
Abstract (from CDS):
This is the first of a series of three papers exploring the connection between the multiwavelength properties of AGNs in nearby early-type galaxies and the characteristics of their hosts. We selected two samples, both with high resolution 5GHz VLA observations available and providing measurements down to 1mJy level, reaching radio-luminosities as low as 1019W/Hz. We focus on the 116 radio-detected galaxies as to boost the fraction of AGN with respect to a purely optically selected sample. Here we present the analysis of the optical brightness profiles based on archival HST images, available for 65 objects. We separate early-type galaxies on the basis of the slope of their nuclear brightness profiles, into core and power-law galaxies following the Nuker's scheme, rather than on the traditional morphological classification (i.e. into E and S0 galaxies). Our sample of AGN candidates is indistinguishable, when their brightness profiles are concerned, from galaxies of similar optical luminosity but hosting weaker (or no) radio-sources. We confirm previous findings that relatively bright radio-sources (Lr>1021.5W/Hz) are uniquely associated to core galaxies. However, below this threshold in radio-luminosity core and power-law galaxies coexist and they do not show any apparent difference in their radio-properties. Not surprisingly, since our sample is deliberately biased to favour the inclusion of active galaxies, we found a higher fraction of optically nucleated galaxies. Addressing the multiwavelength properties of these nuclei will be the aim of the two forthcoming papers.
galaxies: active - galaxies: bulges - galaxies: elliptical and lenticular, cD - galaxies: nuclei - galaxies: structure
In Table 1 NGC 3988 is a misprint for NGC 3998.