Dynamics of Abell 3266 - I. An Optical View of a Complex Merging Cluster
  We present spectroscopy of 880 galaxies within a 2-degree field around the
massive, merging cluster Abell 3266. This sample, which includes 704 new
measurements, was combined with the existing redshifts measurements to generate
a sample of over 1300 spectroscopic redshifts; the largest spectroscopic sample
in the vicinity of A3266 to date. We define a cluster sub-sample of 790
redshifts which lie within a velocity range of 14,000 to 22,000 kms$^{-1}$ and
within 1 degree of the cluster centre. A detailed structural analysis finds
A3266 to have a complex dynamical structure containing six groups and filaments
to the north of the cluster as well as a cluster core which can be decomposed
into two components split along a northeast-southwest axis, consistent with
previous X-ray observations. The mean redshift of the cluster core is found to
be $0.0594 \pm 0.0005$ and the core velocity dispersion is given as
$1462^{+99}_{-99}$ kms$^{-1}$. The overall velocity dispersion and redshift of
the entire cluster and related structures are $1337^{+67}_{-67}$ kms$^{-1}$ and
$0.0596 \pm 0.0002$, respectively, though the high velocity dispersion does not
represent virialised motions but rather is due to relative motions of the
cluster components. We posit A3266 is seen following a merger along the
northeast southwest axis, however, the rich substructure in the rest of the
cluster suggests that the dynamical history is more complex than just a simple
merger with a range of continuous dynamical interactions taking place. It is
thus likely that turbulence in A3266 is very high, even for a merging cluster.
