H I absorption towards radio Active Galactic Nuclei of different
  accretion modes
  We present results of H I absorption experiment done using the Giant
Metrewave Radio Telescope (GMRT) towards 27 low- and intermediate-luminosity
($P_{\rm 1.4 GHz}$ $\sim$10$^{23}$-10$^{26}$ W Hz$^{-1}$) radio active galactic
nuclei (AGN), classified as either low excitation radio galaxies (LERGs) or
high excitation radio galaxies (HERGs) and with WISE colour W2[4.6
$\mu$m]$-$W3[12 $\mu$m]$>$ 2. We report H I absorption detection towards seven
radio AGNs, six of which are new. Combined with other sources from literature
classified as LERGs or HERGs, we confirm our earlier result that compact radio
AGNs with WISE colour W2$-$W3 $>$2 have higher detection rates compared to
those with W2$-$W3 $<$2. We find that H I absorption detection rate is higher
for HERGs (37.0$^{+15.8}_{-11.5}$ per cent) compared to LERGs
(22.0$^{+3.9}_{-3.4}$ per cent), mainly due to a larger fraction of HERGs being
gas and dust rich with a younger stellar population compared to LERGs. However,
for similar compact radio structures and host galaxies with WISE colours
W2$-$W3$>$2, we don't find any significant difference in detection rates of two
types of AGNs implying detection of H I gas may not necessarily mean high
excitation mode AGN. We further analysed the kinematics towards these sources.
We find that while LERGs show a wide range in the shift of centroid velocities
($\sim$ $-$479 to $+$356 km s$^{-1}$) relative to the optical systemic
velocity, most of the HERGs have centroid velocity shift less than 200 km
s$^{-1}$, possibly due to differences in jet-interstellar medium interaction.
