Radio Galaxy Zoo Talk

Large Diffuse source

  • Peter_Dzwig by Peter_Dzwig

    Is this a single source or several different ones co-incidentally aligned? The sources at top right and below centre both look quite diffuse. There looks to be only one IR-bright source and I can't get either z or extent so can't estimate its size. Anyone able to help?


  • ivywong by ivywong scientist, admin

    Indeed. This looks quite large! Potentially a #giant candidate? @HAndernach, what do you think?


  • HAndernach by HAndernach scientist, translator

    Looks definitely like a single source in FIRST, and with an unusual way
    of a "restarted" morphology. Due SE the first knot is the brighter,
    followed by a diffuse lobe, while this is more or less opposite
    on the NW side. There seems to be a radio core of ~1.3 mJy, FIRST
    J171840.455+515336.86 which is listed as extended by ~5.8"@145deg in
    the FIRST catalog, which is quite close to the major source axis, so it
    could be the bases of a single or even twin jet from the core.

    Unfortunately the region is out of the SDSS footprint, but checking in
    VizieR ( I found a galaxy PGC 2402142
    (see 2402142&ob=ra)
    which is quite bright (R~17 B~18.9 mag) and extended (>10") which is clearly the
    host galaxy, and coincides with GALEXASC J171840.86+515334.8, There is another
    galaxy at J171838.01+515403.6 which in NED is GALEXASC J171838.04+515402.5, or
    also 2MASS J17183794+5154033 (i.e. a 2MASS point source, but clearly extended
    on the Digitized Sky Survey). Unfortunately NED doesn't have the corresponding
    optical galaxy names, although they were published in 2000A&AS..146...19P
    Unfortunately the galaxies are not even in the 2MASX catalog, for which
    photometric redshifts were recently published (2014ApJS..210....9B).
    However, given its extent and apparently brightness, I don't think
    it would have a redshift higher than ~0.25, and with a total size of only
    2.3' it would not exceed much more than 0.5 Mpc.

    By the way, the source (though not its optical ID) was already mentioned in
    2011ApJS..194...31Proctor's paper on source groups in FIRST