Evolution of the brightest cluster galaxies: the influence of
  morphology, stellar mass and environment
  Using a sample of 425 nearby Brightest Cluster Galaxies (BCGs) from von der
Linden et al. (2007), we study the relationship between their internal
properties (stellar masses, structural parameters and morphologies) and their
environment. More massive BCGs tend to inhabit denser regions and more massive
clusters than lower mass BCGs. Furthermore, cDs, which are BCGs with
particularly extended envelopes, seem to prefer marginally denser regions and
tend to be hosted by more massive halos than elliptical BCGs. cD and elliptical
BCGs show parallel positive correlations between their stellar masses and
environmental densities. However, at a fixed environmental density, cDs are, on
average, ~40% more massive. Our results, together with the findings of previous
studies, suggest an evolutionary link between elliptical and cD BCGs. We
suggest that most present-day cDs started their life as ellipticals, which
subsequently grew in stellar mass and size due to mergers. In this process, the
cD envelope developed. The large scatter in the stellar masses and sizes of the
cDs reflects their different merger histories. The growth of the BCGs in mass
and size seems to be linked to the hierarchical growth of the structures they
inhabit: as the groups and clusters became denser and more massive, the BCGs at
their centres also grew. This process is nearing completion since the majority
(~60%) of the BCGs in the local Universe have cD morphology. However, the
presence of galaxies with intermediate morphological classes (between
ellipticals and cDs) suggests that the growth and morphological transformation
of some BCGs is still ongoing.
