Multi-wavelength Observations of the Dissociative Merger in the Galaxy
  Cluster CIZA J0107.7+5408
  We present results based on X-ray, optical, and radio observations of the
massive galaxy cluster CIZA J0107.7+5408. We find that this system is a post
core passage, dissociative, binary merger, with the optical galaxy density
peaks of each subcluster leading their associated X-ray emission peaks. This
separation occurs because the diffuse gas experiences ram pressure forces while
the effectively collisionless galaxies (and presumably their associated dark
matter halos) do not. This system contains double peaked diffuse radio
emission, possibly a double radio relic with the relics lying along the merger
axis and also leading the X-ray cores. We find evidence for a temperature peak
associated with the SW relic, likely created by the same merger shock that is
powering the relic radio emission in this region. Thus, this system is a
relatively rare clean example of a dissociative binary merger, which can in
principle be used to place constraints on the self-interaction cross-section of
dark matter. Low frequency radio observations reveal ultra-steep spectrum
diffuse radio emission that is not correlated with the X-ray, optical, or high
frequency radio emission. We suggest that these sources are radio phoenixes,
which are preexisting non-thermal particle populations that have been
re-energized through adiabatic compression by the same merger shocks that power
the radio relics. Finally, we place upper limits on inverse Compton emission
from the SW radio relic.
