Diffuse radio emission in the complex merging galaxy cluster Abell 2069
  Galaxy clusters with signs for a recent merger show in many cases extended
diffuse radio features. This emission originates from relativistic electrons
which suffer synchrotron losses due to the intra-cluster magnetic field. The
mechanisms of the particle acceleration and the properties of the magnetic
field are still poorly understood. We search for diffuse radio emission in
galaxy clusters. Here, we study the complex galaxy cluster Abell 2069, for
which X-ray observations indicate a recent merger. We investigate the cluster's
radio continuum emission by deep Westerbork Synthesis Radio Telescope (WSRT)
observations at 346 MHz and a Giant Metrewave Radio Telescope (GMRT)
observation at 322 MHz. We find an extended diffuse radio feature roughly
coinciding with the main component of the cluster. We classify this emission as
a radio halo and estimate its lower limit flux density to 25 +/- 9 mJy.
Moreover, we find a second extended diffuse source located at the cluster's
companion and estimate its flux density to 15 +/- 2 mJy. We speculate that this
is a small halo or a mini-halo. If true, this cluster is the first example of a
double-halo in a single galaxy cluster.
