Sliding not sloshing in Abell 3744: the influence of radio galaxies NGC
  7018 and 7016 on cluster gas
  We present new X-ray (Chandra) and radio (JVLA) observations of the nearby
cluster Abell 3744. It hosts two prominent radio galaxies with powers in the
range critical for radio-mode feedback. The radio emission from these galaxies
terminates in buoyant tendrils reaching the cluster's outer edge, and the
radio-emitting plasma clearly influences the cluster's X-ray-emitting
atmosphere. The cluster's average gas temperature, of kT=3.5 keV, is high for
its bolometric luminosity of 3.2 \times 10^{43} ergs s^{-1}, but the 100
kpc-scale cavity carved out by radio-emitting plasma shows evidence of less
than 2 per cent of the excess enthalpy. We suggest instead that a high-velocity
encounter with a galaxy group is responsible for dispersing and increasing the
entropy of the gas in this non-cool-core cluster. We see no evidence for
shocks, or established isobaric gas motions (sloshing), but there is much
sub-structure associated with a dynamically active central region that
encompasses the brightest radio emission. Gas heating is evident in directions
perpendicular to the inferred line of encounter between the infalling group and
cluster. The radio-emitting tendrils run along boundaries between gas of
different temperature, apparently lubricating the gas flows and inhibiting heat
transfer. The first stages of the encounter may have helped trigger the radio
galaxies into their current phase of activity, where we see X-rays from the
nuclei, jets, and hotspots.
