Radio Galaxy Zoo Talk

ARG0003qrg: host has bright nucleus but not an AGN spectrum

  • JeanTate by JeanTate

    In ARG0003qrg: zsp 0.281 host SDSS J085749.80+013530.3 has a bright nucleus, like an AGN:

    enter image description here

    Yet its spectrum is boring, like that of a normal elliptical with fading emission ... except that it's ~white, not at all red! 😮

    enter image description here

    Strange, no?

    Posted

  • ivywong by ivywong scientist, admin

    Many AGN have large bulges so the brightness is coming from the large concentration of stars in the centre of this galaxy. If you were to fit a radial profile to this galaxy, I'm pretty sure that you'll get a fit with a Sersic index of 4, typical for an elliptical.

    Posted

  • JeanTate by JeanTate in response to ivywong's comment.

    Thanks Ivy.

    Well, to me, the SDSS image has all the hallmarks of an AGN:

    • the nucleus is 'star-like'
    • it's white (the nuclei of ellipticals are rarely white)
    • there's a pinkish shade on one side (AGNs with clearly resolved host galaxies almost always produce strange color effects in SDSS images)

    If you were to fit a radial profile to this galaxy, I'm pretty sure that you'll get a fit with a Sersic index of 4, typical for an elliptical.

    I've been meaning to get back to my Linux box, and run GALFIT over quite a few galaxies; thanks for the motivation to actually do that! 😃

    Posted