tokens: We thank the anonymous referee for useful comments. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Support for this work was provided by the National Aeronautics and Space Administration through Chandra Award Number GO5-16133X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics and Space Administration under contract NAS8-03060. R.J.W. is supported by a Clay Fellowship awarded by the Harvard-Smithsonian Center for Astrophysics. W.R.F., C.J., and F.A.-S. acknowledge support from the Smithsonian Institution. F.A.-S. acknowledges support from Chandra grant GO3-14131X. Basic research in radio astronomy at NRL by TEC is supported by 6.1 Base funding. M.N. acknowledges PRIN-INAF 2014 1.05.01.94.02. This research made use of APLpy, an open-source plotting package for Python (Robitaille Bressert 2012 ). This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013 ).
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