We have presented multi-wavelength observations of the unusually large FR II radio galaxy NVSS 2146+82. The overall size of the radio source is 4 h50-1 Mpc, making it the second largest known FR II source. We have found the host galaxy to be similar in both luminosity and morphology to a sample of other low redshift FR II galaxies. Emission line profiles seen in the spectrum of the host galaxy are double peaked, which may indicate that the ionized gas may be being accelerated by the bipolar radio jet.
We have also found evidence for an anomalously rich group of galaxies at the same redshift as NVSS 2146+82 that has little associated X-ray emitting gas. Though unusual in having a rich environment, this source is similar to other low redshift FR IIs in clusters; the NVSS 2146+82 group is underluminous in X-rays compared to clusters of similar richness that contain no FR II. The large radio size, lack of significant Faraday rotation and non detection of X-rays all suggest that in spite of the richness of the cluster in which this galaxy resides, it has a low gas density.
There is some morphological evidence that the host galaxy of NVSS 2146+82 may be undergoing tidal interaction with one or more of its nearest companions. Also, an interaction may be responsible for the double-peaked emission line profiles, however the spatial resolution of the spectrum of the nucleus is not high enough to distinguish between a merger origin or radio jet/cloud interaction origin for the peculiar profiles.
Apart from the radio spectral index anomaly, the radio properties of this source are like a normal FR II source scaled up by a factor of ten, preserving the standard overall morphology and polarization structure. In the outer regions of the source the magnetic field is likely to be so weak that inverse Compton losses to the Cosmic Microwave Background dominate synchrotron losses.
We are grateful to Mark Whittle for many helpful conversations. We are grateful to Matt Bershady, Randy Phelps, and Mike Siegel for either sharing observing time or taking observations in support of this research. CP acknowledges the support of a Grant-in-aid of Research from Sigma Xi, the Scientific Research Society. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge the use of NASA's SkyView facility (http://skyview.gsfc.nasa.gov) located at NASA Goddard Space Flight Center.