  A temperature map of the A3266 galaxy cluster has been derived from the ASCA
GIS observations. It shows an asymmetric pattern of heating indicative of an
ongoing merger between a group sized sub-cluster and the main cluster. The
galaxy distribution shows two peaks connected in a barlike structure running NE
to SW through the central region of the main cluster, defining the merger axis.
The temperature of the intergalactic medium generally decreases from SW to NE
along the merger axis with a peak of 13.2 +3.4/-2.0 keV in a region which is
perpendicular to the merger axis and extends through the main cluster density
peak. The central bar has a velocity dispersion of ~1300 km/s, compared to
\~1000 km/s for the surrounding cluster. The central bar also has two distinct
density peaks in the distribution of galaxies, yet it has a velocity
distribution which is consistent with a single Gaussian. This implies a merger
in the plane of the sky. The optical and X-ray data taken together show that a
loose group of about ~30 galaxies has penetrated the main cluster from the SW,
decoupling from their original intergroup medium and passing through a strong
shock front. Two radio galaxies, one a wide angle tail morphology (WAT) and the
other a narrow angle tail (NAT), are located to the SW of the main cluster in
the post-shock gas. Since the merger is in the plane of the sky, a dynamical
analysis cannot be applied to derive the velocity of the merger. Alternatively,
using the pre- and post-shock gastemperature and assuming an adiabatic shock,
we calculate a relative gas velocity of ~1400 km/s. The alignment of the NAT
and WAT relative to the shock front combined with the high gas velocity from
the merger implies that the observed radio morphologies formed via ram-pressure
as a result of the merger.

Astrophysics