KAT-7 detection of radio halo emission in the Triangulum Australis
  galaxy cluster
  We report the presence of high significance diffuse radio emission from the
Triangulum Australis cluster using observations made with the KAT-7 telescope
and propose that this emission is a giant radio halo. We compare the radio
power from this proposed halo with X-ray and SZ measurements and demonstrate
that it is consistent with the established scaling relations for cluster
haloes. By combining the X-ray and SZ data we calculate the ratio of
non-thermal to thermal electron pressure within Triangulum Australis to be
$X=0.658\pm0.054$. We use this ratio to constrain the maximum magnetic field
strength within the halo region to be $B_{\rm max, halo} = 33.08\,\mu$G and
compare this with the minimum field strength from equipartition of $B_{\rm min,
halo} = 0.77(1+k)^{2/7}\,\mu$G to place limits on the range of allowed magnetic
field strength within this cluster. We compare these values to those for more
well-studied systems and discuss these results in the context of equipartition
of non-thermal energy densities within clusters of galaxies.
