Suzaku study of gas properties along filaments of A2744
  Context: We present the results of Suzaku observations of a massive galaxy
cluster A2744, which is an active merger at $z=0.308$. Aims: By using long
X-ray observations of A2744, we aim to understand the growth of the cluster and
the gas heating process through mass accretion along the surrounding filaments.
Methods: We analyzed data from two-pointed Suzaku observations of A2744 to
derive the temperature distribution out to the virial radius in three different
directions. We also performed a deprojection analysis to study radial profiles
of gas temperature, density, and entropy and compared the X-ray results with
multi-wavelength data to investigate correlations with the surface density of
galaxies and with radio relics. Results: The gas temperature was measured out
to the virial radius $r_{200}$ in the north-east region and to about
$1.5r_{200}$ in the north-west and south regions. The radial profile of the gas
temperature is rather flat and the temperature is very high (even near
$r_{200}$); it is comparable to the mean temperature of this cluster ($kT=9$
keV). These characteristics have not been reported in any other cluster. We
find a hint of temperature jump in the northeast region whose location
coincides with a large radio relic, indicating that the cluster experienced gas
heating because of merger or mass accretion onto the main cluster. The
temperature distribution is anisotropic and shows no clear positive correlation
with the galaxy density, which suggests an inhomogeneous mass structure and a
complex merger history in A2744.
