We analyze the near-infrared luminosity profiles and photometric parameters of the host galaxies of 3CR radio sources with z < 0.3 , to investigate their physical nature .
Our sample includes 82 galaxies , of which 22 ( 27 % ) are FR Is and 60 ( 73 % ) are FR IIs .
Using near-infrared data taken both with NICMOS onboard the Hubble Space Telescope and from the ground with the Telescopio Nazionale Galileo , we find that luminosity profiles are very well described by a single Sérsic law in 52 % of the cases and for the remaining objects ( 48 % ) it is necessary to include an exponential profile , which could indicate the presence of a disk .
The average bulge to disk luminosity ratio for the galaxies is ( b / d ) \sim 1.1 .
The analysis of the photometric parameters of the sub samples indicates that FR Is and FR IIs show rather similar bulges in terms of effective surface magnitude , effective radius , and Sérsic index .
On the other hand , disks in FR Is and FR IIs hosts show , on average , different properties .
Central surface magnitudes are dimmer and scale lengths are greater by a factor of 2 in FR Is when compared to FR IIs . We also estimate the black hole mass associated with each galaxy using two different methods that claim tight correlations between the black hole mass ( M _ { BH } ) with the infrared bulge luminosity ( L _ { bulge } ) and with the Sérsic index ( n ) .
Our data indicate that masses obtained through these two methods show a high dispersion and M _ { BH } obtained through L _ { bulge } are systematically higher ( by a factor of \sim 3 ) than those obtained using n .
This result may reflect the fact that for our sample galaxies we do not find any correlation between L _ { bulge } and n .