  We study a complete and distance-limited sample of 25 LINERs, 21 of which
have been imaged with the Hubble Space Telescope to study their physical
properties and to compare their radio and optical properties with those of
other samples of local AGNs, namely Seyfert galaxies and low-luminosity radio
galaxies (LLRG). Our results show that the LINERs population is not
homogeneous, as there are two subclasses: i) the first class is similar to
LLRG, as it extends the population of radio-loud nuclei to lower luminosities;
ii) the second is similar to Seyferts, and extends the properties of
radio-quiet nuclei towards the lowest luminosities. The different nature of the
various classes of local AGN are best understood when the fraction of the
Eddington luminosity they irradiate L_o/L_Edd is plotted against the nuclear
radio-loudness parameter: Seyferts are associated with relatively high
radiative efficiencies L_o/L_Edd >~ 10^-4 (and high accretion rates onto low
mass black holes); LLRG are associated with low radiative efficiencies (and low
accretion rates onto high black hole masses); all LINERs have low radiative
efficiency (and accretion rates), and can be radio-loud or radio quiet
depending on their black hole mass.
