Radio Galaxy Zoo Talk

ARG00000tk - SDRAGN?

  • Dolorous_Edd by Dolorous_Edd

    From DSS impossible to tell what it is

    The host 2MASS 15234587+633924

    Looks like QSO, but listed on NED and SIMBAD as Seyfert 1 Galaxy

    enter image description here

    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    Assuming the classification as Seyfert is correct, it's a spiral (by definition, Seyferts are spirals with a particular kind of AGN).

    Who gave it the Seyfert tag, and how did they make that call?

    Posted

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

    Ned link

    Reference for Activity Type is 2006A&A...455..773V: A catalogue of quasars and active nuclei: 12th edition

    Spectrum ref is http://arxiv.org/abs/astro-ph/9711268

    Class is BLRG broad emission-line radio-galaxy

    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    Class is BLRG broad emission-line radio-galaxy

    Right. That paper reports one Sy1, but it's not this galaxy (it's 1518+40, at z=0.065). 2MASS 15234587+633924 is, I think, 1523+63, with z=0.204.

    Interestingly, Laurent-Muehleisen et al. define a Seyfert as (Section 4.1):

    Distinctions are also generally made between radio-loud and -quiet objects and between objects with high and low optical luminosities (e.g., quasars and Seyfert galaxies, respectively)

    and:

    Following Kellermann et al. (1989), we define radio-loud objects as those having log(Sr/Sopt) > 1.0 where the radio flux density is the core emission measured at 5 GHz and the optical flux density is measured from the POSS O plates. This parameter is then used to distinguish radio-quiet vs. radio-loud quasars and also Seyfert vs. radio galaxies

    Furthermore:

    The division between quasars and low power AGN (Seyfert and radio galaxies) is traditionally based on the Johnson B magnitude (4400 ̊A effective wavelength) and lies between −23.0 < MB < −21.0 mag (Osterbrock, 1989)

    So, I was wrong. For radio astronomers, a Seyfert is a low luminosity, radio-quiet galaxy! 😮

    Posted

  • Dolorous_Edd by Dolorous_Edd

    so, not SDRAGN candidate? QSO?

    Seyfert 1 Galaxy class comes from 2006A&A...455..773V

    There are also 13 ref in SIMBAD

    2012ApJ...751...52E also list it as Sy1

    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    so, not SDRAGN candidate? QSO?

    Ambiguous. But not a QSO (absolute, optical, magnitude/luminosity is too low). For it to be a good SDRAGN candidate, we would need to know what its (optical) morphology is, which we don't (other possible ways to get at 'spiral' are unlikely to work, given that the nucleus dominates the spectrum, and very likely the optical colors).

    2012ApJ...751...52E also list it as Sy1

    Derivative of VCV (which is 2006A&A...455..773V); e.g. Section 4.2:

    We used the VCV spectroscopic galaxy classification to organize these sources into four subclasses: Seyfert 1 AGN (VCV classifications “S,” "S1–S1.9,” “Q,” and “AG”), blazar AGN (VCV classifications “BL” and “HP”), non-AGN, and unclassified (not in the VCV catalog). (By our restricted
    definition, VCV classification “S2,” and “S3,” which includes LINERs and even some starbursts, all count as non-AGNs).

    I'll check VCV later, but from memory it's just a consolidated list, with, perhaps, a light-touch re-definition to attempt a consistent classification scheme.

    Posted