Galaxy And Mass Assembly (GAMA): The environments of high- and low-
  excitation radio galaxies
  We study the environments of low- and high- excitation radio galaxies (LERGs
and HERGs respectively) in the redshift range $0.01 < z < 0.4$, using a sample
of 399 radio galaxies and environmental measurements from the Galaxy And Mass
Assembly (GAMA) survey. In our analysis we use the fifth nearest neighbour
density ($\Sigma_{5}$) and the GAMA galaxy groups catalogue (G3Cv6) and
construct control samples of galaxies matched in {\update stellar mass and
colour} to the radio-detected sample.
  We find that LERGs and HERGs exist in different environments and that this
difference is dependent on radio luminosity. High-luminosity LERGs ($L_{\rm
NVSS} \gtrsim 10^{24}$ W Hz$^{-1}$) lie in much denser environments than a
matched radio-quiet control sample (about three times as dense, as measured by
$\Sigma_{5}$), and are more likely to be members of galaxy groups
($82^{+5}_{-7}$ percent of LERGs are in GAMA groups, compared to $58^{+3}_{-3}$
percent of the control sample). In contrast, the environments of the HERGs and
lower luminosity LERGs are indistinguishable from that of a matched control
sample. Our results imply that high-luminosity LERGs lie in more massive haloes
than non-radio galaxies of similar stellar mass and colour, in agreement with
earlier studies (Wake et al. 2008; Donoso et al. 2010). When we control for the
preference of LERGs to be found in groups, both high- and low- luminosity LERGs
are found in higher-mass haloes ($\sim 0.2$ dex; at least 97 percent
significant) than the non-radio control sample.
