Radio Galaxy Zoo: discovery of a poor cluster through a giant wide-angle
  tail radio galaxy
  We have discovered a previously unreported poor cluster of galaxies (RGZ-CL
J0823.2+0333) through an unusual giant wide-angle tail radio galaxy found in
the Radio Galaxy Zoo project. We obtained a spectroscopic redshift of
$z=0.0897$ for the E0-type host galaxy, 2MASX J08231289+0333016, leading to
M$_r = -22.6$ and a $1.4\,$GHz radio luminosity density of $L_{\rm 1.4} =
5.5\times10^{24}$ W Hz$^{-1}$. These radio and optical luminosities are typical
for wide-angle tailed radio galaxies near the borderline between Fanaroff-Riley
(FR) classes I and II. The projected largest angular size of $\approx8\,$arcmin
corresponds to $800\,$kpc and the full length of the source along the curved
jets/trails is $1.1\,$Mpc in projection. X-ray data from the XMM-Newton archive
yield an upper limit on the X-ray luminosity of the thermal emission
surrounding RGZ J082312.9+033301,at $1.2-2.6\times10^{43}$ erg s$^{-1}$ for
assumed intra-cluster medium temperatures of $1.0-5.0\,$keV. Our analysis of
the environment surrounding RGZ J082312.9+033301 indicates that RGZ
J082312.9+033301 lies within a poor cluster. The observed radio morphology
suggests that (a) the host galaxy is moving at a significant velocity with
respect to an ambient medium like that of at least a poor cluster, and that (b)
the source may have had two ignition events of the active galactic nucleus with
$10^7\,$yrs in between. This reinforces the idea that an association between
RGZ J082312.9+033301, and the newly discovered poor cluster exists.
