  We study the radio emission of the most massive galaxies in a sample of
dynamically relaxed and un-relaxed galaxy groups from Galaxy and Mass Assembly
(GAMA). The dynamical state of the group is defined by the stellar dominance of
the brightest group galaxy, e.g. the luminosity gap between the two most
luminous members, and the offset between the position of the brightest group
galaxy and the luminosity centroid of the group. We find that the radio
luminosity of the most massive galaxy in the group strongly depends on its
environment, such that the brightest group galaxies in dynamically young
(evolving) groups are an order of magnitude more luminous in the radio than
those with a similar stellar mass but residing in dynamically old (relaxed)
groups. This observation has been successfully reproduced by a newly developed
semi-analytic model which allows us to explore the various causes of these
findings. We find that the fraction of radio loud brightest group galaxies in
the observed dynamically young groups is ~2 times that in the dynamically old
groups. We discuss the implications of this observational constraint on the
central galaxy properties in the context of galaxy mergers and the
super-massive blackhole accretion rate.
