  Abell 3667 is a nearby merging cluster with a prominent cold front and a pair
of two bright radio relics. Assuming a head-on merger, the origin of the cold
front is often considered to be a remnant of the cluster core stripped by its
surrounding ICM. Some authors have proposed an offset merger scenario in which
the subcluster core rotates after the first core crossing. This scenario can
reproduce features such as the cold front and a pair of radio relics. To
distinguish between these scenarios, we reanalyzed the ICM distribution and
measured the line-of-sight bulk ICM velocity using the XMM-Newton PN data. In
the unsharp masked image, we identify several ICM features. The notable feature
is a RG1 vortex, which is a clockwise vortex-like enhancement with a radius of
about 250 kpc connecting the first BCG to the radio galaxy (RG1). It is
particularly enhanced near the north of the 1st BCG, which is named the BCG-N
tail. The thermodynamic maps show that the ICM of the RG1 vortex has a
relatively high abundance of 0.5-0.6 solar compared to the surrounding regions.
The ICM of the BCG-E tail also has a high abundance and low pseudo-entropy and
can be interpreted as a remnant of the cluster core's ICM. Including its
arc-like shape, the RG1 vortex supports the idea that the ICM around the
cluster center is rotating, which is natural for an offset merger scenario. The
results of the line-of-sight bulk ICM velocity measurements show that the ICM
around the BCG-N tail is redshifted with a velocity difference of 940+/-440
km/s compared to the optical redshift of the first BCG. We obtain other
indications of variations in the line-of-sight velocity of the ICM and discuss
these in the context of an offset merger.
